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Introduction: The gut bacteria of insects play an important role in regulating their metabolism, immune system and metabolizing pesticides. Our previous results indicate that carvacrol has certain gastric toxic activity on Lymantria dispar larvae and affects their detoxification metabolism at the mRNA level. However, the impact of carvacrol on the gut bacteria of L. dispar larvae has been unclear. Methods: In this study, the 16S rRNA sequencing technology was used to sequence and analyze the gut bacteria of the larvae which were exposed with sublethal concentration (0.297mg/mL) and median lethal concentration (1.120mg/mL), respectively. Results: A total of 10 phyla, 16 classes, 47 orders, 72 families, 103 genera, and 135 species were obtained by using a 97% similarity cutoff level. The dominant bacterial phyla in the gut of the L. dispar larvae are Firmicutes and Proteobacteria. The treatment with carvacrol can significantly affect the structure of gut bacteria in the larvae of the L. dispar. At both doses, carvacrol can shift the dominant gut bacteria of the larvae from Proteobacteria to Firmicutes. At the genus level, two doses of carvacrol can significantly enhance the relative abundance of probiotic Lactobacillus in the gut of L. dispar larvae (p = 0.01). Additionally, significant differences were observed among the five bacterial genera Burkholderia-Caballeronia-Paraburkholderia, Anoxybacillus, Pelomonas, Mesorhizobium (p = 0.05). The analysis of α-diversity and β-diversity indicates that the treatment with carvacrol at two doses significantly affect the bacterial richness and diversity in the larvae. However, the results of functional classification prediction (PICRUSt) indicate that carvacrol significantly down-regulate 7 functions, including Energy metabolism, Cell growth and death, and up-regulate 2 functions, including Carbohydrate metabolism and Membrane transport. The network analysis indicates that the correlation between gut bacteria also has been changed. In addition, the insecticidal activity results of carvacrol against L. dispar larvae with gut bacteria elimination showed that gut bacteria can reduce the insecticidal activity of carvacrol against L. dispar larvae. Discussion: This study provides a theoretical foundation for understanding the role of gut bacteria in detoxifying plant toxins and conferring pesticide resistance. [ABSTRACT FROM AUTHOR]

Simple Summary: The gut microbiota plays important roles for maintaining the health of the host. In this study, the results revealed significant differences in the gut bacterial communities among bean geese, hooded cranes, and domestic geese. In comparison to domestic geese, the gut bacterial community of bean geese and hooded cranes had a greater capacity for energy metabolism, suggesting that wild birds may rely more on their gut microbiota to survive in cold conditions. Furthermore, pathogens were discovered to overlap among the three hosts, reminding us to monitor the potential for pathogen transmission between poultry and wild birds. Hooded cranes showed the highest diversity and relative abundance of pathogens compared to the other two species. Due to its vulnerable status, more focus should be paid to the protection of the hooded crane species. These findings could help us gain a deeper understanding of the structure of gut bacterial and pathogenic communities in poultry and wild birds. The host's physiological well-being is intricately associated with the gut microbiota. However, previous studies regarding the intestinal microbiota have focused on domesticated or captive birds. This study used high-throughput sequencing technology to identify the gut bacterial communities of sympatric bean geese, hooded cranes, and domestic geese. The results indicated that the gut bacterial diversity in domestic geese and hooded cranes showed considerably higher diversity than bean geese. The gut bacterial community compositions varied significantly among the three hosts (p < 0.05). Compared to the hooded crane, the bean goose and domestic goose were more similar in their genotype and evolutionary history, with less difference in the bacterial community composition and assembly processes between the two species. Thus, the results might support the crucial role of host genotypes on their gut microbiota. The gut bacteria of wild hooded cranes and bean geese had a greater capacity for energy metabolism compared to domestic geese, suggesting that wild birds may rely more on their gut microbiota to survive in cold conditions. Moreover, the intestines of the three hosts were identified as harboring potential pathogens. The relative abundance of pathogens was higher in the hooded crane compared to the other two species. The hooded crane gut bacterial community assemblage revealed the least deterministic process with the lowest filtering/selection on the gut microbiota, which might have been a reason for the highest number of pathogens result. Compared to the hooded crane, the sympatric bean goose showed the least diversity and relative abundance of pathogens. The intestinal bacterial co-occurrence network showed the highest stability in the bean goose, potentially enhancing host resistance to adverse environments and reducing the susceptibility to pathogen invasion. In this study, the pathogens were also discovered to overlap among the three hosts, reminding us to monitor the potential for pathogen transmission between poultry and wild birds. Overall, the current findings have the potential to enhance the understanding of gut bacterial and pathogenic community structures in poultry and wild birds. [ABSTRACT FROM AUTHOR]

Background: Spodoptera frugiperda, the fall armyworm is a destructive invasive pest, and S. litura the tobacco cutworm, is a native species closely related to S. frugiperda. The gut microbiota plays a vital role in insect growth, development, metabolism and immune system. Research on the competition between invasive species and closely related native species has focused on differences in the adaptability of insects to the environment. Little is known about gut symbiotic microbe composition and its role in influencing competitive differences between these two insects. Methods: We used a culture-independent approach targeting the 16S rRNA gene of gut bacteria of 5th instar larvae of S. frugiperda and S. litura. Larvae were reared continuously on maize leaves for five generations. We analyzed the composition, abundance, diversity, and metabolic function of gut microbiomes of S. frugiperda and S. litura larvae. Results: Firmicutes, Proteobacteria, and Bacteroidetes were the dominant bacterial phyla in both species. Enterococcus, ZOR0006, Escherichia, Bacteroides, and Lactobacillus were the genera with the highest abundance in S. frugiperda. Enterococcus, Erysipelatoclostridium, ZOR0006, Enterobacter, and Bacteroides had the highest abundance in S. litura. According to α-diversity analysis, the gut bacterial diversity of S. frugiperda was significantly higher than that of S. litura. KEGG analysis showed 15 significant differences in metabolic pathways between S. frugiperda and S. litura gut bacteria, including transcription, cell growth and death, excretory system and circulatory system pathways. Conclusion: In the same habitat, the larvae of S. frugiperda and S. litura showed significant differences in gut bacterial diversity and community composition. Regarding the composition and function of gut bacteria, the invasive species S. frugiperda may have a competitive advantage over S. litura. This study provides a foundation for developing control strategies for S. frugiperda and S. litura. [ABSTRACT FROM AUTHOR]

Nitrite exposure has become a significant concern in the aquaculture industry, posing a severe threat to aquatic animals such as shrimp. While studies have reported the adverse effects of nitrite on shrimp growth, the part played by the gut microbiota in shrimp mortality resulting from nitrite exposure is poorly understood. Here, the effects of nitrite on shrimp gut bacterial community were investigated using 16S rRNA amplicon sequencing, bacterial isolation, genomic analysis, and infection experiments. Compared to the control_healthy group, changes in the bacterial composition of the nitrite_dead group were associated with reduced abundance of specific beneficial bacteria and increased abundance of certain pathogenic bacteria. Notably, members of the Photobacterium genus were found to be significantly enriched in the nitrite_dead group. Genomic analysis of a representative Photobacterium strain (LvS-8n3) revealed a variety of genes encoding bacterial toxins, including hemolysin, adhesin, and phospholipase. Furthermore, it was also found that LvS-8n3 exhibits strong pathogenicity, probably due to its high production of pathogenic factors and the ability to utilize nitrite for proliferation. Therefore, the proliferation of pathogenic Photobacterium species appears pivotal for driving shrimp mortality caused by nitrite exposure. These findings provide novel insights into the disease mechanism in shrimp under conditions of environmental change.

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Background Spodoptera frugiperda, the fall armyworm is a destructive invasive pest, and S. litura the tobacco cutworm, is a native species closely related to S. frugiperda. The gut microbiota plays a vital role in insect growth, development, metabolism and immune system. Research on the competition between invasive species and closely related native species has focused on differences in the adaptability of insects to the environment. Little is known about gut symbiotic microbe composition and its role in influencing competitive differences between these two insects. Methods We used a culture-independent approach targeting the 16S rRNA gene of gut bacteria of 5th instar larvae of S. frugiperda and S. litura. Larvae were reared continuously on maize leaves for five generations. We analyzed the composition, abundance, diversity, and metabolic function of gut microbiomes of S. frugiperda and S. litura larvae. Results Firmicutes, Proteobacteria, and Bacteroidetes were the dominant bacterial phyla in both species. Enterococcus, ZOR0006, Escherichia, Bacteroides, and Lactobacillus were the genera with the highest abundance in S. frugiperda. Enterococcus, Erysipelatoclostridium, ZOR0006, Enterobacter, and Bacteroides had the highest abundance in S. litura. According to α-diversity analysis, the gut bacterial diversity of S. frugiperda was significantly higher than that of S. litura. KEGG analysis showed 15 significant differences in metabolic pathways between S. frugiperda and S. litura gut bacteria, including transcription, cell growth and death, excretory system and circulatory system pathways. Conclusion In the same habitat, the larvae of S. frugiperda and S. litura showed significant differences in gut bacterial diversity and community composition. Regarding the composition and function of gut bacteria, the invasive species S. frugiperda may have a competitive advantage over S. litura. This study provides a foundation for developing control strategies for S. frugiperda and S. litura.

Owing to its high economic and nutritional value, Apostichopus japonicus is an important mariculture species in North China. Because of the rapid development of its aquaculture industry in recent years, the limitations of traditional aquaculture modes such as pond aquaculture, cofferdam aquaculture, and beach aquaculture have become increasingly prominent. Therefore, the high-efficiency and healthy northern suspension cage A. japonicus breeding model, with the best comprehensive benefits and the least management problems, came into being. Microorganisms, as an essential part of the aquaculture pond ecosystem, not only play an important role in the material circulation and energy flow of the ecosystem, but also have great significance in maintaining ecosystem balance. As a representative invertebrate, echinoderms such as A. japonicus have a simple digestive structure. Bacteria account for a large proportion of the gut microbiome of A. japonicus, providing more than 70% of their energy demand. The bacterial community is closely related to the healthy growth of the host and plays an important role in digestion and metabolism, defense against pathogens, and immune function. However, the complex bacterial community in the gut of aquaculture species depends on the culture environment, and there is a close symbiotic relationship between the environmental and gut bacterial community which affects the survival and growth of organisms, disease occurrence, and material circulation. Previous studies have shown that the complex bacterial community in the gut of A. japonicus primarily comes from their habitat and maintains a relatively stable dynamic balance with the external environmental community. In order to improve the growth capacity of A. japonicus and quality of the culture water, it is important to understand the structural characteristics of the bacterial communities of A. japonicus and their culture water to support the development of the A. japonicus aquaculture industry. This information will provide a theoretical reference for the healthy aquaculture of A. japonicus and assist with disease prevention and control. Clarifying the complex relationship between the structure and functional characteristics of bacterial communities and the aquaculture environment, as well as the important role of the bacterial community in growth, will support future research on the bacterial community mechanisms, explore ways to improve the ecological regulation of breeding yield, and promote the healthy development of the A. japonicus culture industry. To date, there have been limited studies on the correlation between the gut bacterial community structure of A. japonicus and its culture environment.At present, most of the existing studies are based on the traditional pure culture or separation and enrichment culture methods, which cannot accurately reflect natural bacterial communities. In recent years, high-throughput sequencing technology has introduced a new way to comprehensively analyze the structural and functional characteristics of bacterial communities by combining several bioinformatics methods. With the continuous development of molecular sequencing technology, 16S rRNA high-throughput sequencing technology has become a valuable tool to study the structure of bacterial communities. It has been widely used to study a variety of ecosystems and bacterial community diversity, providing a novel means to study the species diversity and quantity of bacterial communities, and the structural and functional characteristics of bacterial communities. Most of the relevant existing studies are based on the structure and diversity of the bacterial community of A. japonicus cultured in the south, whereas only a few studies have been conducted on the structure and functional characteristics of bacterial communities of A. japonicus cultured in suspension cages in the north. Therefore, in order to investigate the relationship between the bacterial community structure of A. japonicus and the culture water, this study analyzed their structural and functional characteristics in cage-cultured A. japonicus in North China using high-throughput sequencing technology, and preliminarily discussed the correlation between them. The results showed that the diversity and richness of the A. japonicus gut bacterial community were significantly higher than those of the culture water (P < 0.05). The dominant bacteria in the gut of A. japonicus and the culture water were Proteobacteria and Bacteroidetes. There were 13 common core bacteria with a relative abundance greater than 0.1%. In addition, the bacterial communities showed some independence; the specific phyla in the gut belonged to Firmicutes and Chloroflexi, represented by Bacillus, Lactobacillus, Halioglobus, Lutimonas, and Woeseia. Based on an analysis of the Kyoto Encyclopedia of Genes and Genomes (KEGG) metabolic pathway database, a total of 300 tertiary metabolic pathways was annotated, among which 146 tertiary metabolic pathways had highly significant differences (P < 0.001). The specific metabolic pathways in the gut of A. japonicus were mainly carbohydrate digestion and absorption, protein digestion and absorption, and sphingolipid metabolism. This study showed that the bacterial community in the gut of A. japonicus is similar to that of the culture water, but there were significant differences in the relative community abundance. The results of this study provide a theoretical basis for the healthy cultivation of northern A. japonicus in suspension cages.

Microbiota that live in gut of the insects have a wide range of effects on host physiology, nutrition, and behaviour. To characterize the gut bacterial community of orthopteran pests comprehensively, we selected Oedaleus decorus asiaticus as a representative pest to more explicitly test the influence of host dietary niche on the gut bacterial community. Illumina high‐throughput sequencing technology was used to study the gut bacterial community of O. d. asiaticus, a key pest on natural grasslands in China. The results showed that the gut bacterial community of O. d. asiaticus ingesting on Poa poophagorum had the highest diversity but lowest richness, and Proteobacteria and Firmicutes were dominant phylum. There were significant differences in the gut bacterial structure of O. d. asiaticus after ingesting different grasses. Most of functional prediction pathways were concentrated in metabolism and cellular processes. The diversity of the gut bacterial community associated with Carex sutschanensis, Sipapurpurea, and Agropyron cristatum was positively associated with crude protein (Ca) (p < 0.05), phosphorus (P) (p < 0.05), and ether extract (EE) (p < 0.05). The abundance of Pantoea, Wolbachia, Enterobacter, Escherichia, and Enterococcus was positively related to P and EE. The abundance of Pantoea, Wolbachia, Enterobacter, Enterococcus, Succiniclasticum, Lactobacillus, and Acinetobacter was positively related to crude protein. The abundance of Escherichia, Muribaculum, Succiniclasticum, Lactobacillus, Acinetobacter was positively related to Ca and dry matter. The abundance of Muribaculum, Succiniclasticum, Lactobacillus, Acinetobacter was positively related to acid detergent fibre, neutral detergent fibre, and crude ash. These results suggest that the grass with higher overall nutritional content has higher abundance of immune bacteria. This investigation of the gut bacterial community may provide insights into the relationships between grasses, pests, and their gut bacterial communities, and find new ways to control locust outbreaks by targeting the insect bacterial community. [ABSTRACT FROM AUTHOR]

Background: Atopic dermatitis (AD) patients have high rates of colonization by Staphylococcus aureus, which has been associated with worsening of the disease. This study characterized Staphylococcus spp isolates recovered from nares and feces of pediatric patients with AD in relation to antimicrobial susceptibility, staphylococcal cassette chromosome mec (SCCmec) type, presence of pvl genes and clonality. Besides, gut bacterial community profiles were compared with those of children without AD. Results: All 55 AD patients evaluated had colonization by Staphylococcus spp. Fifty-three (96.4%) patients had colonization in both clinical sites, whereas one patient each was not colonize in the nares or gut. Staphylococcus aureus was identified in the nostrils and feces of 45 (81.8%) and 39 (70.9%) patients, respectively. Methicillin-resistant Staphylococcus spp. isolates were found in 70.9% of the patients, and 24 (43.6%) had methicillin-resistant S. aureus (MRSA). S. aureus (55.6%) and S. epidermidis (26.5%) were the major species found. The prevalent lineages of S. aureus were USA800/SCCmecIV (47.6%) and USA1100/SCCmecIV (21.4%), and 61.9% of the evaluated patients had the same genotype in both sites. Additionally, gut bacterial profile of AD patients exhibits greater dissimilarity from the control group than it does among varying severities of AD. Conclusions: High rates of nasal and intestinal colonization by S. aureus and methicillin-resistant staphylococci isolates were found in AD patients. Besides, gut bacterial profiles of AD patients were distinctly different from those of the control group, emphasizing the importance of monitoring S. aureus colonization and gut microbiome composition in AD patients. [ABSTRACT FROM AUTHOR]

Intestinal parasites, such as Eimeria, are common among plateau pika (Ochotona curzoniae). The gut microbiome is an essential driver of the host response to gastrointestinal parasites. However, the effects of intestinal protozoal parasites on the temporal variations in the gut microbiome and behavioral and physiological activities remain unknown. Our study conducted treatments involving experimental feeding of pika with Eimeria oocysts or anticoccidia under laboratory conditions to focus on the parasite-associated alterations in gut bacterial communities, host behavioral activity, physiology, and host-bacteria relationships. The results showed insignificant differences in bacterial community structures among treatments on the basis of Bray-Curtis distance metrics, whereas the patterns of temporal alterations in the bacterial communities were changed by the treatments. Bacterial alpha diversities did not vary with the treatments, and experimental feeding with Eimeria slowed down the decrement rate of alpha diversity. Furthermore, few bacterial members were significantly changed by the treatments--only the genus Ruminococcus and the species Ruminococcus flavefaciens, which were associated with energy metabolism. Experimental feeding with Eimeria modified the temporal variations in the bacterial members, including a lower loss rate of the relative abundance of the dominant families Muribaculaceae and Ruminococcaceae in the group with Eimeria experimental feeding. Moreover, a shifting energy tradeoff was suggested by the parasite-induced increments in thyroid hormones (triiodothyronine and tetraiodothyronine) and decrements in exploration behavior in the group with Eimeria feeding. However, we did not detect specific connections between gut bacterial communities and pika behaviors and physiology in terms of energy trade-offs. Further in-depth research is needed to examine the role of Eimeria-modified differences in the gut bacteria of plateau pika. [ABSTRACT FROM AUTHOR]

Accumulating evidence demonstrates that it is of great importance to maintain a stable and functional gut microbial community for host's growth and health. However, gut microenvironment is constantly affected by diverse environmental factors. Salinity can cause stress, including hypersaline or hyposaline stress to aquatic species, thereby affecting their growth conditions. Razor clam (Sinonovacula constricta), an economically important bivalve species, inhabits in intertidal and estuarine zones and constantly experiences salinity stress. Yet little is known about how and to what extent clam gut microbiota is affected by salinity stress, while this knowledge is fundamental for clam aquaculture health management. To address this concern, this study compared the temporal differences of gut bacterial signatures and community assembly of S. constricta under normal salinity (NS), low salinity (LS), and high salinity (HS) conditions. Acute salinity stress affected the compositions, structures, and functional potentials of clam gut microbial community, of which salinity stress, hours post stress, and their interaction respectively constrained 7.6%, 16.4%, and 7.9% of community variation. Phylogenetic bin-based null model result revealed that the gut bacterial assembly of three salinity groups seemed to be largely driven by stochastic processes. Network analysis indicated that gut bacterial interspecies interaction exhibited less connected and lower cooperative activity under the conditions of LS and HS compared with NS. Notably, some pathogenic bacteria, including Vibrio and Pseudoalteromonas, were identified as keystone taxa of gut microbial networks in LS and HS groups. Above findings suggest that the clams under LS and HS conditions might be at a higher risk of developing disease. Our findings enhance the mechanism understanding of gut microbial assembly in S. constricta under abiotic factor challenge, which has important implications for clam health control from a microbial ecological perspective. [ABSTRACT FROM AUTHOR]

The host’s physiological well-being is intricately associated with the gut microbiota. However, previous studies regarding the intestinal microbiota have focused on domesticated or captive birds. This study used high-throughput sequencing technology to identify the gut bacterial communities of sympatric bean geese, hooded cranes, and domestic geese. The results indicated that the gut bacterial diversity in domestic geese and hooded cranes showed considerably higher diversity than bean geese. The gut bacterial community compositions varied significantly among the three hosts (p < 0.05). Compared to the hooded crane, the bean goose and domestic goose were more similar in their genotype and evolutionary history, with less difference in the bacterial community composition and assembly processes between the two species. Thus, the results might support the crucial role of host genotypes on their gut microbiota. The gut bacteria of wild hooded cranes and bean geese had a greater capacity for energy metabolism compared to domestic geese, suggesting that wild birds may rely more on their gut microbiota to survive in cold conditions. Moreover, the intestines of the three hosts were identified as harboring potential pathogens. The relative abundance of pathogens was higher in the hooded crane compared to the other two species. The hooded crane gut bacterial community assemblage revealed the least deterministic process with the lowest filtering/selection on the gut microbiota, which might have been a reason for the highest number of pathogens result. Compared to the hooded crane, the sympatric bean goose showed the least diversity and relative abundance of pathogens. The intestinal bacterial co-occurrence network showed the highest stability in the bean goose, potentially enhancing host resistance to adverse environments and reducing the susceptibility to pathogen invasion. In this study, the pathogens were also discovered to overlap among the three hosts, reminding us to monitor the potential for pathogen transmission between poultry and wild birds. Overall, the current findings have the potential to enhance the understanding of gut bacterial and pathogenic community structures in poultry and wild birds.

Abstract Background Diaphorina citri Kuwayama is an important citrus pest. It serves as the vector for the transmission of Candidatus Liberibacter asiaticus (CLas), which induced a destructive disease, Huanglongbing, and caused huge economic losses. During the interaction between insects and plants, insects have evolved a series of mechanisms to adapt to various host plants. Murraya exotica and ‘Shatangju’ mandarin (Citrus reticulate cv. Shatangju) are the Rutaceae species from different genera that have been discovered as suitable hosts for D. citri adults. While the adaptation mechanism of this pest to these two host plants is unclear. Results In this study, RNA-seq and 16 S rDNA amplification sequencing were performed on the gut of D. citri adults reared on M. exotica and ‘Shatangju’ mandarin. RNA-seq results showed that a total of 964 differentially expressed genes were found in different gut groups with two host plant treatments. The impacted genes include those that encode ribosomal proteins, cathepsins, and mitochondrial respiratory chain complexes. According to 16 S rDNA sequencing, the compositions of the gut bacterial communities were altered by different treatments. The α and β diversity analyses confirmed that the host plant changes influenced the gut microbial diversity. The functional classification analysis by Tax4Fun revealed that 27 KEGG pathways, mostly those related to metabolism, including those for nucleotide metabolism, energy metabolism, metabolism of cofactors and vitamins, amino acid metabolism, carbohydrate metabolism, xenbiotics biodegradation and metabolism, lipid metabolism, and biosynthesis of other secondary metabolites, were significantly altered. Conclusion Our preliminary findings shed light on the connection between D. citri and host plants by showing that host plants alter the gene expression profiles and bacterial community composition of D. citri adults.

The intestinal bacteria of longhorn beetles would be ideal targets for pest control and lignocellulosic resources by destroying or exploiting their cellulose-degrading function. This article aims to investigate the diversity and community structure of intestinal bacteria the oligophagous longhorn beetle Glenea cantor. Additionally, it seeks to identify the presence of lignocellulose-degrading bacteria in the gut, and explore their role in consuming host kapok trees Bombax malabaricum. In this study, the bacterial community from G. cantor was examined by Illumina sequencing of 16S ribosomal RNA (rRNA) targeting the V3 and V4 regions. A total of 563,201 valid sequences and 814 OTUs were obtained. The dominant phyla were Proteobacteria, and the dominant genera were Acinetobacter and Lactococcus. The analysis of microbial diversity revealed a high bacterial diversity in the samples, with the gut bacteria playing a crucial role in the physiological activities of the host, particularly, 9 genera of intestinal bacteria with cellulose degradation function were found, highlighting their vital role in cellulose degradation. Five strains of cellulose-degrading bacteria, belonging to the genus Pseudomonas, were obtained from the intestinal tract of G. cantor larvae using traditional isolation and culture techniques as well as 16S rDNA sequencing. Among these strains, A4 exhibited a cellulase activity of 94.42 ± 0.42 U/mL, while A5 displayed the highest filter paper enzyme activity of 127.46 ± 3.54 U/mL. These results offered valuable insights into potential targets for pest control through internal attack digestion and cellulose-degrading bacteria in longhorn beetles.

Intestinal microbiota plays an important role in promoting digestion, metabolism, and immunity. Intestinal microbiota and fatty acids are important indicators to evaluate the health and nutritional composition of Procambarus clarkii. They have been shown to be strongly influence by environmental and genetic factors. However, it is not clear whether environmental factors have a greater impact on the intestinal microbiota and fatty acid composition of crayfish. The link between the intestinal microbial communities and fatty acid (FA) compositions of red swamp crayfish from different geographical has not yet been studied. Thus, the current paper focuses on the influence of different environments on the fatty acids in muscles of crayfish and the possible existence between gut microbiota and fatty acids. Therefore, in this study, we compared the fatty acid compositions and intestinal microbiota of five crayfish populations from different geographical locations. The results were further analyzed to determine whether there is a relationship between geographical location, fatty acid compositions and intestinal microbiota. The gut microbial communities of the crayfish populations were characterized using 16S rRNA high-throughput gene sequencing. The results showed that there were significant differences in FA compositions of crayfish populations from different geographical locations. A similar trend was observed in the gut microbiome, which also varied significantly according to geographic location. Interestingly, the analysis revealed that there was a relationship between fatty acid compositions and intestinal microbes, revealed by alpha diversity analysis and cluster analysis. However, further studies of the interactions between the P. clarkii gut microbiota and biochemical composition are needed, which will ultimately reveal the complexity of microbial ecosystems with potential applications in aquaculture and species conservation. [ABSTRACT FROM AUTHOR]

The fitness of an organism is often impacted by the composition and biological activity of its associated bacterial community. Many factors, including host genetics, diet, and temperature can influence the bacterial community composition. Furthermore, these factors can differ strongly between natural and laboratory environments. Consequently, several studies have highlighted results from laboratory experiments investigating host-associated bacterial communities to be conflicting with those obtained under field conditions. Here, we compared the Daphnia magna gut bacterial communities in natural host populations with those of laboratory cultured hosts. We further analyzed changes in the gut bacterial communities after transferring hosts from natural populations to the laboratory on the short- and long-term. Results show that, in general, the gut bacterial communities from natural populations differ from those of laboratory cultures and that their composition and diversity changed one hour after being transferred to the laboratory. Over the following 14 days, the composition and diversity changed gradually. On the longer term (after two years of rearing hosts in the laboratory) the composition and diversity of the gut bacterial communities was strongly altered compared to the initial state. Our findings indicate that the gut bacterial communities of Daphnia magna in laboratory experiments is not representative for natural field conditions, and that caution should be taken when interpreting results from laboratory experiments for natural settings. [ABSTRACT FROM AUTHOR]

Simple Summary: In this study, the researchers investigated the role of gut bacteria in an insect pest called Megalurothrips usitatus and its resistance to an insecticide and an entomopathogenic fungus. They compared the gut bacterial communities of an insecticide-susceptible population and an insecticide-resistant population of Megalurothrips usitatus. Through High-throughput sequencing, they found that the insecticide-resistant population exhibited significantly higher resistance to the insecticide and the Beauveria brongniartii. The sequencing also revealed changes in the abundance of specific bacterial species in response to the insecticide and the Beauveria brongniartii. The researchers observed that the gut bacteria of Megalurothrips usitatus are primarily involved in various metabolic activities, including the degradation of the Beauveria brongniartii. Some of these bacteria may even reduce the virulence of the fungus, thereby weakening its biocontrol ability. The results of this study provide a basis for future elucidation of the role of intestinal bacteria in the symbiotic relationship of insecticide resistance and the design of new management strategies for Megalurothrips usitatus using Beauveria brongniartii for biological control. The gut bacterial microbiota of insects plays a crucial role in physiological, metabolic, and innate immune processes. In the current study, the gut bacterial communities of an insecticide-susceptible (IS), and a resistant (IR) population of a major legume pest, Megalurothrips usitatus (Bagnall), were evaluated. The 16S rDNA V3 + V4 regions of M. usitatus infected with Beauveria brongniartii along with the intestinal flora of both populations were sequenced based on a High-throughput sequencing platform. Toxicological bioassays revealed that the IR population exhibited resistance to acetamiprid and B. brongniartii isolate SB010 at levels of 138.0-fold and 55.6-fold higher, respectively, compared to the IS population. Through 16S High-throughput sequencing, the results indicate that both resistant populations, as well as B. brongniartii infestation, reduce the number of species of M. usitatus gut microbes. Using KEGG function prediction, it was found that most intestinal bacteria were involved in various metabolic activities, and the abundance of resistant populations was higher than that of sensitive populations. The bacteria in the gut of M. usitatus are mainly involved in various metabolic activities to achieve the degradation of B. brongniartii. This study provides valuable insights into the interaction between gut bacteria, insecticide resistance, and Beauveria. brongniartii infection in Megalurothrips usitatus, which can help inform future pest control strategies. [ABSTRACT FROM AUTHOR]

Background: Diaphorina citri Kuwayama is an important citrus pest. It serves as the vector for the transmission of Candidatus Liberibacter asiaticus (CLas), which induced a destructive disease, Huanglongbing, and caused huge economic losses. During the interaction between insects and plants, insects have evolved a series of mechanisms to adapt to various host plants. Murraya exotica and 'Shatangju' mandarin (Citrus reticulate cv. Shatangju) are the Rutaceae species from different genera that have been discovered as suitable hosts for D. citri adults. While the adaptation mechanism of this pest to these two host plants is unclear. Results: In this study, RNA-seq and 16 S rDNA amplification sequencing were performed on the gut of D. citri adults reared on M. exotica and 'Shatangju' mandarin. RNA-seq results showed that a total of 964 differentially expressed genes were found in different gut groups with two host plant treatments. The impacted genes include those that encode ribosomal proteins, cathepsins, and mitochondrial respiratory chain complexes. According to 16 S rDNA sequencing, the compositions of the gut bacterial communities were altered by different treatments. The α and β diversity analyses confirmed that the host plant changes influenced the gut microbial diversity. The functional classification analysis by Tax4Fun revealed that 27 KEGG pathways, mostly those related to metabolism, including those for nucleotide metabolism, energy metabolism, metabolism of cofactors and vitamins, amino acid metabolism, carbohydrate metabolism, xenbiotics biodegradation and metabolism, lipid metabolism, and biosynthesis of other secondary metabolites, were significantly altered. Conclusion: Our preliminary findings shed light on the connection between D. citri and host plants by showing that host plants alter the gene expression profiles and bacterial community composition of D. citri adults. [ABSTRACT FROM AUTHOR]

The gut microbiota plays an integral role in the metabolism and immunity of animal hosts, and provides insights into the health and habitat assessment of threatened animals. The skywalker hoolock gibbon (Hoolock tianxing) is a newly described gibbon species, and is considered an endangered species. Here, we used 16S rRNA amplicon sequencing to describe the fecal bacterial community of skywalker hoolock gibbons from different habitats and in captivity. Fecal samples (n = 5) from two captive gibbons were compared with wild populations (N = 6 gibbons, n = 33 samples). At the phylum level, Spirochetes, Proteobacteria, Firmicutes, Bacteroidetes dominated in captive gibbons, while Firmicutes, Bacteroidetes, and Tenericutes dominated in wild gibbons. At the genus level, captive gibbons were dominated by Treponema‐2, followed by Succinivibrio and Cerasicoccus, while wild gibbons were dominated by Anaeroplasma, Prevotellaceae UCG‐001, and Erysipelotrichaceae UCG‐004. Captive rearing was significantly associated with lower taxonomic alpha‐diversity, and different relative abundance of some dominant bacteria compared to wild gibbons. Predicted Kyoto Encyclopedia of Genes and Genomes pathway analyses showed that captive gibbons have significantly lower total pathway diversity and higher relative abundance of bacterial functions involved in "drug resistance: antimicrobial" and "carbohydrate metabolism" than wild gibbons. This study reveals the potential influence of captivity and habitat on the gut bacterial community of gibbons and provides a basis for guiding the conservation management of captive populations. Research Highlight: Captive and wild hoolock skywalker gibbons have different gut microbial structures.Captive rearing was significantly associated with lower taxonomic alpha‐diversity, different relative abundance of some dominant bacteria and the number of pathways compared to wild gibbons.Predicted Kyoto Encyclopedia of Genes and Genomes pathway showed that captive gibbons have significant more abundant functional gene pathways of "drug resistance: antimicrobial" and "carbohydrate metabolism" than wild gibbons. [ABSTRACT FROM AUTHOR]

Nitrite exposure has become a significant concern in the aquaculture industry, posing a severe threat to aquatic animals such as shrimp. While studies have reported the adverse effects of nitrite on shrimp growth, the part played by the gut microbiota in shrimp mortality resulting from nitrite exposure is poorly understood. Here, the effects of nitrite on shrimp gut bacterial community were investigated using 16S rRNA amplicon sequencing, bacterial isolation, genomic analysis, and infection experiments. Compared to the control_healthy group, changes in the bacterial composition of the nitrite_dead group were associated with reduced abundance of specific beneficial bacteria and increased abundance of certain pathogenic bacteria. Notably, members of the Photobacterium genus were found to be significantly enriched in the nitrite_dead group. Genomic analysis of a representative Photobacterium strain (LvS-8n3) revealed a variety of genes encoding bacterial toxins, including hemolysin, adhesin, and phospholipase. Furthermore, it was also found that LvS-8n3 exhibits strong pathogenicity, probably due to its high production of pathogenic factors and the ability to utilize nitrite for proliferation. Therefore, the proliferation of pathogenic Photobacterium species appears pivotal for driving shrimp mortality caused by nitrite exposure. These findings provide novel insights into the disease mechanism in shrimp under conditions of environmental change. • Nitrite-induced death of shrimp is associated with dysbiosis of gut bacterial community. • Photobacterium are significantly enriched in the nitrite_dead group. • A member of this genus (LvS-8n3) exhibits strong pathogenicity towards shrimp. • LvS-8n3 has the potential to produce various toxins and multiple ways to metabolize nitrite. [ABSTRACT FROM AUTHOR]

It is well-documented that perturbation of the gut bacterial community can influence the reproductive rates of the host. Less is known about how natural ecological processes can change the bacterial composition in the gut and how such changes influence the reproductive rate of the host. Here, we provide novel experimental insights into such processes using the clonally reproducing water flea, Daphnia magna. A total of 20 replicate cultures were reared for 5 weeks (Phase 1) to allow for divergence of bacterial communities through stochastic processes (i.e. drift, founder effects, and/or colonization). Duplicate cultures created from each of these were reared for 21 days (Phase 2) while recording reproductive rates. There was a significant repeatability in reproductive rates between these duplicates, suggesting that divergence of the bacterial communities during Phase 1 translated into reproductive rate effects during Phase 2. This was further supported by significant differences in the relative abundance of gut bacteria (investigated by amplicon sequencing of a part of the 16S rRNA gene) between cultures with high and low reproductive rate in Phase 2. These results are consistent with the hypothesis that stochastic processes can cause natural variation in the bacterial composition in the gut, which in turn affect host reproductive rates. [ABSTRACT FROM AUTHOR]

Simple Summary: Although locusts can cause major agricultural damage, they also constitute a valuable food resource. At present, L. migratoria manilensis has been largely domesticated, being considered an edible insect in China. Feeding variety is one of the main characteristics of L. migratoria manilensis. There are apparent differences in the capacity of locusts to adapt to different food plants. To elucidate the effect of different food plants (i.e., goosegrass, maize leaves, soybean leaves, and pakchoi) on the growth and development of L. migratoria manilensis, the gut bacterial community composition of L. migratoria manilensis fifth instars fed on different plants was analyzed by high-throughput sequencing. Gut bacterial communities were affected by food plants and may play an essential role in host adaption. Feeding on different food plants has significant effects on the growth and development of L. migratoria manilensis. The present study establishes a theoretical foundation for studying the interplay between gut bacteria structure and L. migratoria manilensis adaptation. Locusts, in particular Locusta migratoria manilensis (Meyen), have been associated with major damages in agriculture, forestry, and animal husbandry in China. At present, L. migratoria manilensis has been largely domesticated, being considered an edible insect in China. Feeding variety is one of the main characteristics of L. migratoria manilensis. It has been demonstrated that microorganisms inhabiting the insect gut impact nutrition, development, defense, and reproduction of the insect host. The aim of the present study was to search for the adaptation mechanism of L. migratoria manilensis feeding on four different food plants (goosegrass, maize leaves, soybean leaves, and pakchoi) and explore changes in the gut bacterial community structure of the insect at the fifth instar nymph stage. Proteobacteria and Firmicutes were the dominant phyla, whereas Kluyvera, Enterobacter, Pseudocitrobacter, Klebsiella, Cronobacter, Citrobacter, Lactococcus, and Weissella were the dominant genera in the gut of L. migratoria manilensis. Principal component analysis and permutational multivariate analysis of variance (PERMANOVA) revealed significant differences in the gut microbiota structure of L. migratoria manilensis fed on different food plants. Moreover, functional prediction analysis revealed that metabolic and cellular processes were the most enriched categories. Within the category of metabolic processes, the most enriched pathways were carbohydrate transport and metabolism; amino acid transport and metabolism; translation, ribosomal structure, and biogenesis; cell wall/membrane/envelope biogenesis; inorganic ion transport and metabolism; and energy production and conversion. Collectively, the present results revealed that the structure of gut bacterial communities in L. migratoria manilensis fed on different food plants is impacted by food plants, which may play an essential part in the adaptation of the host. [ABSTRACT FROM AUTHOR]

Introduction: The gut bacteria of insects play an important role in regulating their metabolism, immune system and metabolizing pesticides. Our previous results indicate that carvacrol has certain gastric toxic activity on Lymantria dispar larvae and affects their detoxification metabolism at the mRNA level. However, the impact of carvacrol on the gut bacteria of L. dispar larvae has been unclear., Methods: In this study, the 16S rRNA sequencing technology was used to sequence and analyze the gut bacteria of the larvae which were exposed with sublethal concentration (0.297 mg/mL) and median lethal concentration (1.120 mg/mL), respectively., Results: A total of 10 phyla, 16 classes, 47 orders, 72 families, 103 genera, and 135 species were obtained by using a 97% similarity cutoff level. The dominant bacterial phyla in the gut of the L. dispar larvae are Firmicutes and Proteobacteria . The treatment with carvacrol can significantly affect the structure of gut bacteria in the larvae of the L. dispar . At both doses, carvacrol can shift the dominant gut bacteria of the larvae from Proteobacteria to Firmicutes . At the genus level, two doses of carvacrol can significantly enhance the relative abundance of probiotic Lactobacillus in the gut of L. dispar larvae ( p  ≤ 0.01). Additionally, significant differences were observed among the five bacterial genera Burkholderia-Caballeronia-Paraburkholderia , Anoxybacillus , Pelomonas , Mesorhizobium ( p ≤ 0.05). The analysis of α -diversity and β -diversity indicates that the treatment with carvacrol at two doses significantly affect the bacterial richness and diversity in the larvae. However, the results of functional classification prediction (PICRUSt) indicate that carvacrol significantly down-regulate 7 functions, including Energy metabolism, Cell growth and death, and up-regulate 2 functions, including Carbohydrate metabolism and Membrane transport. The network analysis indicates that the correlation between gut bacteria also has been changed. In addition, the insecticidal activity results of carvacrol against L. dispar larvae with gut bacteria elimination showed that gut bacteria can reduce the insecticidal activity of carvacrol against L. dispar larvae., Discussion: This study provides a theoretical foundation for understanding the role of gut bacteria in detoxifying plant toxins and conferring pesticide resistance., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Yang, Chen and Zhang.)

The neotropical otter (Lontra longicaudis) is considered a flagship species for the conservation of the ecosystems in which it resides and is currently in a vulnerable state. As a conservation strategy for this species, rehabilitation, breeding, and reintroduction programs of captive individuals have been proposed. However, it is likely that the environment and feeding conditions in captivity result in gut microbial communities that differ from those in wild animals. Gut microbial communities have an important role in the physiological performance of an animal. To determine differences between gut microbial communities of otters in wild and captive living conditions, the structure and diversity of their gut bacterial communities were determined using 16S rDNA molecular markers. Total DNA was isolated from fecal samples of wild animals from the La Vieja River basin and from captive animals in the Cali Zoo. As expected, the gut bacterial communities of captive animals converged to a more similar structure, and their bacterial diversity was significantly lower than that found in wild animals.

The gut bacterial microbiota of insects plays a crucial role in physiological, metabolic, and innate immune processes. In the current study, the gut bacterial communities of an insecticide-susceptible (IS), and a resistant (IR) population of a major legume pest, Megalurothrips usitatus (Bagnall), were evaluated. The 16S rDNA V3 + V4 regions of M. usitatus infected with Beauveria brongniartii along with the intestinal flora of both populations were sequenced based on a High-throughput sequencing platform. Toxicological bioassays revealed that the IR population exhibited resistance to acetamiprid and B. brongniartii isolate SB010 at levels of 138.0-fold and 55.6-fold higher, respectively, compared to the IS population. Through 16S High-throughput sequencing, the results indicate that both resistant populations, as well as B. brongniartii infestation, reduce the number of species of M. usitatus gut microbes. Using KEGG function prediction, it was found that most intestinal bacteria were involved in various metabolic activities, and the abundance of resistant populations was higher than that of sensitive populations. The bacteria in the gut of M. usitatus are mainly involved in various metabolic activities to achieve the degradation of B. brongniartii. This study provides valuable insights into the interaction between gut bacteria, insecticide resistance, and Beauveria. brongniartii infection in Megalurothrips usitatus, which can help inform future pest control strategies.

The gut microbiota play an important role in digestion, development, nutritional metabolism and detoxification in insects. The rice stem borer, Chilo suppressalis, is one of the most destructive rice pests and has caused serious economic losses to major rice‐producing areas of China. However, little is known about how its gut microbiota has adapted to different geographical environments. We investigated the gut microbiota of C. suppressalis populations collected from five sites in the typical areas of northern China using 16S rDNA gene sequencing on an Illumina MiSeq platform. In total, 453,853,707 reads and 1650 operational taxonomic units (OTUs) in 25 gut samples of C. suppressalis were obtained. We identified 697 bacterial genera from 30 phyla, and Proteobacteria and Firmicutes were the most dominant phyla. Gut bacterial richness and alpha‐diversity metrics revealed no significant differences among these populations. We detected the highest bacterial diversity in Beizhen, western Liaoning Province. Principal coordinates analysis (PCoA) and clustering analysis (UPGMA) showed no distinct gut microbial community structure of C. suppressalis in these regions. Linear discriminant analysis (LDA) effect size (LEfSe) indicated that the bacterial species exhibited significant differences among the middle, northern and western regions. Finally, PICRUSt analysis demonstrated that microbial functions closely associated with the gut microbiome mainly included membrane transport, amino acid metabolism and carbohydrate metabolism. Accordingly, our study provided important insights into the investigation of insect‐bacteria symbioses and evaluated gut microorganisms as biocontrol agents for this pest and other agricultural lepidopterans. [ABSTRACT FROM AUTHOR]

Bacteria are part of the insect gut system and influence many physiological traits of their host. Gut bacteria may even reduce or block the transmission of arboviruses in several species of arthropod vectors. Culicoides biting midges are important arboviral vectors of several livestock and wildlife diseases, yet limited information is available on their gut bacterial communities. Addressing this gap will help inform how these communities can be manipulated and ultimately used as novel tools to control pathogens. To assess how bacterial communities change during the life stages of lab-reared C. nubeculosus and C. sonorensis, endosymbiotic bacteria were identified using Illumina sequencing of 16S rRNA and taxonomically characterised. Analyses were conducted to determine how gut bacterial communities in adults are influenced by species identity and geographic distance among biting midge populations. Communities of the two lab-reared Culicoides species significantly changed after pupation and with maturation into 6-day-old adults. Pseudomonas, Burkholderiaceae and Leucobacter bacteria were part of a core community that was trans-stadially transmitted and found throughout their life cycle. Among field-collected biting midges, the bacterial communities were unique for almost each species. Cardinium, Rickettsia and Wolbachia were some of the most abundant bacteria in midges collected from wetlands. Only Pseudomonas was present in high relative abundance in all field-collected species. In this study, species identity, as well as geographic distance, influenced the gut bacterial communities and may partly explain known inter- and intra-species variability in vector competence. Additionally, stably associated bacterial species could be candidates for paratransgenic strategies to control vector-borne pathogens. [ABSTRACT FROM AUTHOR]

Animals are not only regulated by their own genes but also influenced by symbiotic bacteria, most of which are colonized in the gut. The gut bacterial community is involved in plenty of physiological processes; therefore, intestinal colonization by commensal microbiota is essential to the health of the host animal. Here, metagenome sequencing of the A. japonicus gut, surrounding water, and feed was performed to explore the structural and functional characteristics of the colonized bacteria in the gut of A. japonicus. Results showed that Bacteroidetes and Proteobacteria were the main dominant phyla of the A. japonicus gut, and Formosa, Vibrio, and Lactobacillus were the dominant genera. There was asymmetry between the A. japonicus gut and its surrounding environment in the bacterial community. In terms of the top 50 abundant genera, those colonized in the gut shared a similarity of 26% with those colonized in the surrounding water and a similarity of 30% with those colonized in the feed. According to KEGG annotation, the dominant metabolic pathways in the gut of A. japonicus were glycan biosynthesis and metabolism, nitrogen metabolism, and cysteine and methionine metabolism. This implies that the gut-colonized bacteria of A. japonicus are influenced by the surrounding water and the feed. In addition, the gut-colonized bacteria might be related to the growth and metabolism of A. japonicus. [ABSTRACT FROM AUTHOR]

The aquaculture of the swimming crab Portunus trituberculatus is challenged by vibriosis, and Rhodobacteraceae strains play a crucial role in maintaining gut health and enhancing the immunity of crustaceans. In this study, we investigated the effects of dietary supplementation of Roseovarius litoreus , a member of Rhodobacteraceae, on the survival and immune defense of the swimming crab. The results showed that 60-day dietary supplementation of R. litoreus resulted in a marked increase in the mRNA expression of gut ZO-1. Meanwhile, R. litoreus increased zero-radius operational taxonomic unit (ZOTU) richness and changed the gut bacterial community, which was manifested by the enriched Carboxylicivirga and Roseovarius and depleted Photobacterium and Vibrio , thereby upregulating functional potentials of the gut bacterial community in the immune system and biosynthesis of other secondary metabolites. After a 72-h V. parahaemolyticus challenge, R. litoreus -supplemented crabs had an increased survival rate, reduced histological damage of hepatopancreas and gut, and improved expressions of immune-related genes and lysozyme activity. Moreover, R. litoreus -supplemented crab gut still harbored more Carboxylicivirga and Roseovarius but had fewer Vibrio gene copies than control crabs, which led to similar changes in functional potentials. Notably, all ZOTUs that were positively correlated with immune-related genes and lysozyme activity belonged to Bacteroidetes, Bacteroidales, or Carboxylicivirga. Taken together, we highlight the probiotic role of R. litoreus in the survival and immune defense of the swimming crab. These findings may contribute to the development of indigenous bacteria of the swimming crab as potential probiotics for the control of vibriosis. • The probiotic role of Rhodobacteraceae in helping crabs resist diseases remains poorly characterized. • Roseovarius litoreus supplementation improves survival and immune defense of the swimming crab. • Roseovarius litoreus alters the crab gut bacterial community and promotes gut health. • Roseovarius litoreus is a candidate probiotic in controlling vibriosis. [ABSTRACT FROM AUTHOR]

The pathogenesis of brain inflammation induced by polychlorinated biphenyl 126 (PCB126) has not yet been fully illustrated. Growing evidence highlights the relevance of the microbiota-gut-brain axis in central nervous system (CNS) dysfunction. Therefore, we aimed to study the role of the gut microbiota in PCB126-induced proinflammatory cytokine increases in the mouse brain. The results showed that PCB126 exposure significantly disordered gut bacterial communities, resulting in the enrichment of gram-negative bacteria (e.g., Bacteroidetes and Proteobacteria), further leading to elevated levels of the gram-negative bacterial lipopolysaccharide (LPS). Subsequently, colonic toll-like receptor 4 (TLR-4) was activated by bacterial LPS, which promoted proinflammatory cytokine generation and inhibited tight junction (TJ) protein expression. Then, bacterial LPS translocated from the gut lumen into the blood circulation and reached the brain, triggering LPS/TLR-4-mediated increases in brain proinflammatory cytokines. Further analysis after fecal microbiota transplantation (FMT) suggested that the gut microbiota disturbance caused by PCB126 could induce elevated bacterial LPS and trigger TLR-4-mediated increases in proinflammatory cytokines in the brain. This study highlights the possibility that PCB126-induced gut microbiota disorder contributes to increased brain proinflammatory cytokines. These results provide a new perspective for identifying the toxicity mechanisms of PCB126 and open up the possibility of modulating the gut microbiota as a therapeutic target for CNS disease caused by environmental pollution.

Abstract Isolating relevant microorganisms is still a substantial challenge that limits the use of bacteria in the maintenance of human health. To confirm which media and which bacterial colony densities can enrich certain kinds of bacteria, we selected eight common media and used them to enrich the gut microorganisms on agar plates. Then, we calculated the numbers of bacterial colonies and collected the bacterial culture mixtures from each kind of medium. Using the Illumina HiSeq platform, we analyzed the composition and diversity of the culture-enriched gut bacterial community. Our data suggested that medium supplemented with blood could increase the diversity of the bacterial community. In addition, beef powder and peptone could significantly change the culture-enriched bacterial community. A moderate density (100–150 colony-forming units per plate) was optimal for obtaining the highest diversity on the agar. Similarly, membrane transport was significantly enriched in the moderate-density group, which indicated a more active metabolism in this density range. Overall, these results reveal the optimal culture conditions, including the densities of colonies and nutritional components for various gut bacteria, that provide a novel strategy for isolating bacteria in a way that is targeted and avoids blinded and repetitive work.

• Antipsychotics may impact gut microbiota, but this connection is little understood. • Most studies reported changes in gut microbiota after antipsychotic treatment. • Further understanding on the subject may help to optimize treatment. Antipsychotics (APs) have been increasingly prescribed for psychiatric disorders from schizophrenia to disruptive behavioral conditions. These drugs have been associated with considerable side effects, such as weight gain, and increasing evidence has also indicated that its use impacts gut microbiota (GM), although this connection is still little understood. To assess APs effects on the GM of patients starting or ongoing treatment, a systematic review was carried out in PubMed and Scopus databases. Twelve articles were considered eligible for the review, which investigated the effects of risperidone (5 studies), quetiapine (3), amilsupride (1), olanzapine (1), and unspecified atypical drugs (2). Eleven reported changes in GM in response to APs, and associations between the abundance of bacterial groups and different metabolic parameters were described by most of them. However, the studies were noticeably heterogeneous considering design, methods, and results. In this way, the effects of APs on GM composition and diversity were inconclusive. Despite the uncertain interactions, a more comprehensive understanding on how microbiota is affected by APs may help to optimize treatment, potentially minimizing side effects and improving adherence to treatment. [ABSTRACT FROM AUTHOR]

BACKGROUND Chlorothalonil is a nonsystemic fungicide, and it is one of the most widely detected pesticides in bee hives. The effect of chlorothalonil on the survival, weight, and gut microbiota of immature Apis mellifera L. reared in vitro was studied. RESULTS: Larvae were fed 1, 2, 4, 8, and 16 μg/mL chlorothalonil and compared with larvae fed the negative control (diet without any additives), positive control (45 mg/L dimethoate), and solvent control (2% acetone). Compared with the control groups, the survival of the 2, 4, 8, and 16 μg/mL chlorothalonil treatments was significantly reduced. The no‐observed‐adverse‐effect concentration of chlorothalonil was 1 μg/mL. Chlorothalonil had no significant effect on larval weight. The gut bacterial community composition of newly emerged bees was determined by PacBio 16S rDNA gene sequencing. linear discriminant analysis effect size (LEFSe) analysis showed that Pseudomonadales and Burkholderiales were affected by exposure to chlorothalonil. CONCLUSION: Chlorothalonil reduced the survival of honey bee larvae and altered the gut microbiota of newly emerged bees. The risk of pesticides to honey bees is related to their toxicity and exposure dose. [ABSTRACT FROM AUTHOR]

Locusts, in particular Locusta migratoria manilensis (Meyen), have been associated with major damages in agriculture, forestry, and animal husbandry in China. At present, L. migratoria manilensis has been largely domesticated, being considered an edible insect in China. Feeding variety is one of the main characteristics of L. migratoria manilensis. It has been demonstrated that microorganisms inhabiting the insect gut impact nutrition, development, defense, and reproduction of the insect host. The aim of the present study was to search for the adaptation mechanism of L. migratoria manilensis feeding on four different food plants (goosegrass, maize leaves, soybean leaves, and pakchoi) and explore changes in the gut bacterial community structure of the insect at the fifth instar nymph stage. Proteobacteria and Firmicutes were the dominant phyla, whereas Kluyvera, Enterobacter, Pseudocitrobacter, Klebsiella, Cronobacter, Citrobacter, Lactococcus, and Weissella were the dominant genera in the gut of L. migratoria manilensis. Principal component analysis and permutational multivariate analysis of variance (PERMANOVA) revealed significant differences in the gut microbiota structure of L. migratoria manilensis fed on different food plants. Moreover, functional prediction analysis revealed that metabolic and cellular processes were the most enriched categories. Within the category of metabolic processes, the most enriched pathways were carbohydrate transport and metabolism; amino acid transport and metabolism; translation, ribosomal structure, and biogenesis; cell wall/membrane/envelope biogenesis; inorganic ion transport and metabolism; and energy production and conversion. Collectively, the present results revealed that the structure of gut bacterial communities in L. migratoria manilensis fed on different food plants is impacted by food plants, which may play an essential part in the adaptation of the host.

Administration of all-trans retinoic acid (ATRA) to pregnant sows improves developmental defects of Hoxa1–/– fetal pigs, and this study aimed to explore the influence of maternal ATRA administration during pregnancy on gut microbiota of neonatal piglets. Samples of jejunal and ileal meconium of neonatal piglets before suckling were collected including 5 Hoxa1–/– and 20 non-Hoxa1–/– (Hoxa1+/+ and Hoxa1+/−) neonatal piglets from the control group and 5 Hoxa1–/– and 7 non-Hoxa1–/– neonatal piglets from the experimental group. Results indicated that Hoxa1 mutation shaped the bacterial composition of the jejunum and ileum of neonatal piglets and Hoxa1–/– neonatal piglets had significantly higher diversity and species richness, higher relative abundance of phylum Bacteroidetes, lower relative abundances of phylum Firmicutes and genus Lactobacillus, and lower ratio of Firmicutes to Bacteroidetes than non-Hoxa1–/– neonatal piglets. After maternal ATRA administration, Hoxa1–/– neonatal piglets had significantly higher diversity and species richness, higher relative abundances of two bacterial phyla (Bacteroidetes and Proteobacteria), and lower relative abundances of phylum Firmicutes and genus Lactobacillus in the jejunum than non-Hoxa1–/– neonatal piglets. Hoxa1–/– neonatal piglets delivered by sows with maternal ATRA administration had lower diversity and species richness and higher relative abundance of phylum Firmicutes in the jejunum than Hoxa1–/– neonatal piglets born by sows with no maternal ATRA administration. Non-Hoxa1–/– neonatal piglets delivered by sows with maternal ATRA administration had higher diversity and species richness and significantly lower relative abundances of phyla Firmicutes and Actinobacteria and genus Lactobacillus in the ileum than non-Hoxa1–/– neonatal piglets born by sows with no maternal ATRA administration. Hoxa1 mutation decreased the expression of bacterial genes involved in ABC transporters, purine metabolism, and aminoacyl-tRNA biosynthesis and increased the expression of bacterial genes involved in two-component system, starch and sucrose metabolism, and arginine and proline metabolism. Maternal ATRA administration decreased the expression of bacterial genes involved in arginine and proline metabolism, peptidoglycan biosynthesis, and fatty acid biosynthesis. Hoxa1 mutation resulted in bacterial dysbiosis of the small intestine of Hoaxa1–/– neonatal piglets, and maternal ATRA administration restored the bacterial dysbiosis of Hoxa1–/– neonatal piglets and altered the bacterial composition of the small intestine of non-Hoxa1–/– neonatal piglets.

Administration of all-trans retinoic acid (ATRA) to pregnant sows improves developmental defects of Hoxa1–/– fetal pigs, and this study aimed to explore the influence of maternal ATRA administration during pregnancy on gut microbiota of neonatal piglets. Samples of jejunal and ileal meconium of neonatal piglets before suckling were collected including 5 Hoxa1–/– and 20 non-Hoxa1–/– (Hoxa1+/+ and Hoxa1+/−) neonatal piglets from the control group and 5 Hoxa1–/– and 7 non-Hoxa1–/– neonatal piglets from the experimental group. Results indicated that Hoxa1 mutation shaped the bacterial composition of the jejunum and ileum of neonatal piglets and Hoxa1–/– neonatal piglets had significantly higher diversity and species richness, higher relative abundance of phylum Bacteroidetes, lower relative abundances of phylum Firmicutes and genus Lactobacillus , and lower ratio of Firmicutes to Bacteroidetes than non-Hoxa1–/– neonatal piglets. After maternal ATRA administration, Hoxa1–/– neonatal piglets had significantly higher diversity and species richness, higher relative abundances of two bacterial phyla (Bacteroidetes and Proteobacteria), and lower relative abundances of phylum Firmicutes and genus Lactobacillus in the jejunum than non-Hoxa1–/– neonatal piglets. Hoxa1–/– neonatal piglets delivered by sows with maternal ATRA administration had lower diversity and species richness and higher relative abundance of phylum Firmicutes in the jejunum than Hoxa1–/– neonatal piglets born by sows with no maternal ATRA administration. Non-Hoxa1–/– neonatal piglets delivered by sows with maternal ATRA administration had higher diversity and species richness and significantly lower relative abundances of phyla Firmicutes and Actinobacteria and genus Lactobacillus in the ileum than non-Hoxa1–/– neonatal piglets born by sows with no maternal ATRA administration. Hoxa1 mutation decreased the expression of bacterial genes involved in ABC transporters, purine metabolism, and aminoacyl-tRNA biosynthesis and increased the expression of bacterial genes involved in two-component system, starch and sucrose metabolism, and arginine and proline metabolism. Maternal ATRA administration decreased the expression of bacterial genes involved in arginine and proline metabolism, peptidoglycan biosynthesis, and fatty acid biosynthesis. Hoxa1 mutation resulted in bacterial dysbiosis of the small intestine of Hoaxa1–/– neonatal piglets, and maternal ATRA administration restored the bacterial dysbiosis of Hoxa1–/– neonatal piglets and altered the bacterial composition of the small intestine of non-Hoxa1–/– neonatal piglets. [ABSTRACT FROM AUTHOR]

• How size and concentration of MPs and NPs affect the toxicity on rare minnow was explored. • The toxicity of MPs and NPs was both size- and concentration-dependent. • Significant gut microbiota dysbiosis was observed. • Metabolic disturbance was mostly correlated to the concentration of MPs/NPs. • Gut microbiota and metabolic disorders are putatively interrelated. How the particle size and concentration of microplastics impact their toxicity is largely unknown. Herein, the effects of polystyrene microplastics (1 μm, MPs) and nanoplastics (100 nm, NPs) exposed at 1 mg/L (L) and 10 mg/L (H), respectively, on the growth, histopathology, oxidative stress, gut microbiome, and metabolism of rare minnow (Gobiocypris rarus) were investigated by chemical analysis and multi-omics. MPs and NPs inhibited the growth, induced histopathological injury and aggravated oxidative stress markedly with contrasting significance of particle size and concentration. The composition of core gut microbiota changed dramatically especially for the MPs-H. Similarly, gut bacterial communities were reshaped by the MPs and NPs but only NPs-H decreased both richness and Shannon indexes significantly. Co-occurrence network analysis revealed that the potential keystone genera underwent great changes in exposed groups compared to the control. MPs-H increased the network complexity and the frequency of positive interactions which was opposite to other exposed groups. Moreover, the metabolomic profiles associated with amino acid, lipid, unsaturated fatty acid and hormone metabolism were disturbed significantly especially for MPs-H and NPs-H. In conclusion, the toxicity of MPs depends on both the particle size and concentration, and varies with the specific indicators as well. [ABSTRACT FROM AUTHOR]

Animals are not only regulated by their own genes but also influenced by symbiotic bacteria, most of which are colonized in the gut. The gut bacterial community is involved in plenty of physiological processes; therefore, intestinal colonization by commensal microbiota is essential to the health of the host animal. Here, metagenome sequencing of the A. japonicus gut, surrounding water, and feed was performed to explore the structural and functional characteristics of the colonized bacteria in the gut of A. japonicus. Results showed that Bacteroidetes and Proteobacteria were the main dominant phyla of the A. japonicus gut, and Formosa, Vibrio, and Lactobacillus were the dominant genera. There was asymmetry between the A. japonicus gut and its surrounding environment in the bacterial community. In terms of the top 50 abundant genera, those colonized in the gut shared a similarity of 26% with those colonized in the surrounding water and a similarity of 30% with those colonized in the feed. According to KEGG annotation, the dominant metabolic pathways in the gut of A. japonicus were glycan biosynthesis and metabolism, nitrogen metabolism, and cysteine and methionine metabolism. This implies that the gut-colonized bacteria of A. japonicus are influenced by the surrounding water and the feed. In addition, the gut-colonized bacteria might be related to the growth and metabolism of A. japonicus.

Isolating relevant microorganisms is still a substantial challenge that limits the use of bacteria in the maintenance of human health. To confirm which media and which bacterial colony densities can enrich certain kinds of bacteria, we selected eight common media and used them to enrich the gut microorganisms on agar plates. Then, we calculated the numbers of bacterial colonies and collected the bacterial culture mixtures from each kind of medium. Using the Illumina HiSeq platform, we analyzed the composition and diversity of the culture-enriched gut bacterial community. Our data suggested that medium supplemented with blood could increase the diversity of the bacterial community. In addition, beef powder and peptone could significantly change the culture-enriched bacterial community. A moderate density (100–150 colony-forming units per plate) was optimal for obtaining the highest diversity on the agar. Similarly, membrane transport was significantly enriched in the moderate-density group, which indicated a more active metabolism in this density range. Overall, these results reveal the optimal culture conditions, including the densities of colonies and nutritional components for various gut bacteria, that provide a novel strategy for isolating bacteria in a way that is targeted and avoids blinded and repetitive work. [ABSTRACT FROM AUTHOR]

The gut microbiota plays an important role in a variety of physiological functions such as intestinal digestion, metabolic homeostasis, immune response, and responses to disease treatment. Whether there is a relationship between gut microbial communities and fatty acid (FA) profiles of Chinese mitten crab is unclear. Hence, we analyzed the relationship between FA profiles and the gut bacterial communities of six Chinese mitten crab (Eriocheir sinensis) populations from different lakes. The crabs were sampled from six different lakes in Jiangsu Province, China. The FA profiles of these crab populations were compared and clustered, and then used to determine the relationship between geographic location and FA composition. We also characterized the gut microbial communities of these crabs using 16S rRNA high-throughput gene sequencing. The FA profiles varied significantly (P < 0.05) between crabs from different geographical locations. A similar trend was also observed in the gut microbial communities, which also varied significantly based on their geographical origin (P < 0.05). Furthermore, alpha diversity, cluster analysis, and matching bacterial community structures with specific locations revealed patterns that significantly linked FA profiles to the gut microbiota. Further analysis of FA profiles and gut microbial community generated patterns that linked the two parameters. Hence, it was observed that the gut microbial community seems to contribute significantly to the FA composition of the Chinese mitten crab. However, further studies need to be conducted to investigate the interactions between gut microbial communities and the biochemical composition of the Chinese mitten crab, which will ultimately unravel the complexity of microbial ecosystems for potential applications in aquaculture and species conservation.

Abstract The avian gut microbiota plays an important role in shaping the health of its host. However, knowledge of gut bacteria in birds lags behind that of other animals. In this study, we investigated the gut bacterial communities of lesser white‐fronted geese (Anser erythropus) wintering at Shengjin Lake and Caizi Lake, China, using high‐throughput sequencing (Illumina MiSeq). Altogether, 1,053,624 high‐quality sequences and 4,405 operational taxonomic units (OTUs) were acquired from 30 fecal samples (15 per lake). The OTUs represented eight phyla and 17 classes from the Caizi Lake samples and seven phyla and 16 classes from the Shengjin Lake samples. Firmicutes, Proteobacteria, Actinobacteria, and Bacteroidetes were the dominant phyla. The spatial distance and the Chao1, Simpson, and Shannon indices showed that the alpha diversity differed significantly between the samples from both lakes. The phylogenetic tree and heatmap analyses showed that all the Caizi Lake samples were clustered together and all the Shengjin Lake samples were clustered together. These findings suggest that diet may be an important driver of gut microbial community structure in the birds from each lake, and the obvious differentiation in their gut microbial structures may indicate that the bacteria are highly sensitive to food sources at both lakes.

Abstract Increasing evidence has emerged supporting a tight link between gut bacterial community and shrimp health. However, the knowledge about the variation of gut bacterial community, especially with different disease onset time, remains elusive. Here, healthy and diseased shrimps were collected at 3 disease-outbreak times (day 70, 80 and 85) to investigate the variation of gut bacterial community and its underlying ecological process with 16S rRNA gene amplicon sequencing. The gut bacterial community of diseased shrimp was distinct from the healthy one and temporally less stable, characterized by decreased alpha-diversity and dispersive structure. And its dominant ecological process experienced a transition with disease onset time, although deterministic process mainly governed the healthy gut bacterial assembly. In addition, the core microbiota of healthy shrimp gut harbored more diverse bacterial taxa with more cooperative interactions, while the diseased core microbiota showed opposite pattern with significantly higher abundance of opportunistic pathogens as well. These findings indicate that shrimp heath is highly relevant to the homeostasis of its gut bacterial community. Preservation and restoration of the bacterial community equilibrium could represent an effective strategy for shrimp disease prevention.

The gut microbiota plays an important role in a variety of physiological functions such as intestinal digestion, metabolic homeostasis, immune response, and responses to disease treatment. Whether there is a relationship between gut microbial communities and fatty acid (FA) profiles of Chinese mitten crab is unclear. Hence, we analyzed the relationship between FA profiles and the gut bacterial communities of six Chinese mitten crab (Eriocheir sinensis) populations from different lakes. The crabs were sampled from six different lakes in Jiangsu Province, China. The FA profiles of these crab populations were compared and clustered, and then used to determine the relationship between geographic location and FA composition. We also characterized the gut microbial communities of these crabs using 16S rRNA high-throughput gene sequencing. The FA profiles varied significantly (P < 0.05) between crabs from different geographical locations. A similar trend was also observed in the gut microbial communities, which also varied significantly based on their geographical origin (P < 0.05). Furthermore, alpha diversity, cluster analysis, and matching bacterial community structures with specific locations revealed patterns that significantly linked FA profiles to the gut microbiota. Further analysis of FA profiles and gut microbial community generated patterns that linked the two parameters. Hence, it was observed that the gut microbial community seems to contribute significantly to the FA composition of the Chinese mitten crab. However, further studies need to be conducted to investigate the interactions between gut microbial communities and the biochemical composition of the Chinese mitten crab, which will ultimately unravel the complexity of microbial ecosystems for potential applications in aquaculture and species conservation. [ABSTRACT FROM AUTHOR]

More and more studies have revealed a close relationship between gut microbial community and human health. However, the mechanism why changes in gut microflora structures affect shrimp health status remains unclear. In this study, we compared the differences of bacterial communities among intestine, water, and sediment collected from mariculture ponds of Penaeus japonicus in the early (30 days) and late (90 days) stage. Simultaneously, the relationship between bacterial communities and water quality indexes as well as shrimp physiological indexes was analyzed, respectively. The results showed that relative abundances of intestinal dominant phyla changed along with rearing times. And according to non-metric multidimensional scaling (NMDS), bacterial communities of shrimp gut had a closer relationship with the water library. By analyzing the relationship between water quality indexes and shrimp pond flora, it was shown that total nitrogen and ammonia nitrogen contents probably had the biggest impacts on bacterial communities of water, so did temperature and chemical oxygen demand on microbial communities of sediments and shrimp intestines. By analyzing the relationship between the dominant genus and physiological health indicators of shrimp, it was found that unidentified_Mitochondria, Photobacterium, and Acinetobacter were more closely associated with shrimp physiological health indicators such as total antioxidant capacity, superoxide dismutase activity, antibacterial activity, lysozyme activity, and agglutinating activity. Overall, these results suggested that intestinal microbiota of Penaeus japonicus has certain connections to ambient microflorae, environmental factors, and shrimp health status. These findings may be conducive to disease prevention and control by regulating gut and ambient microflorae in shrimp farming. [ABSTRACT FROM AUTHOR]

The spruce bark beetle (Ips typographus L.) is a destructive pest of Eurasian spruce forests. Although the gut bacteria of this insect are considered to play important roles in its lifecycle, the relationship between I. typographus and its gut bacterial community is poorly characterized. In this study, 16S rRNA gene sequencing was used to determine gut bacterial community composition across successive I. typographus life stages. Responses of the gut bacteria to α-pinene enantiomers were also explored. Ips typographus gut bacterial populations were dominated by the phyla Proteobacteria, Firmicutes, Bacteroidetes, and Actinobacteria, and the relative abundance of these phyla varied across different developmental stages of the beetle. Bacterial species diversity and richness indices increased with developmental stage progression. Relative abundances of the dominant genera, Erwinia (Enterobacteriales: Enterobacteriaceae), Pseudoxanthomonas (Xanthomonadales: Xanthomonadaceae), Serratia (Enterobacteriales: Enterobacteriaceae), and Romboutsia (Clostridiales: Peptostreptococcaceae), also varied across successive I. typographus life stages. Large disparities in the gut bacterial community of male adults were observed when the beetles were treated with S -(–)-α-pinene and R -(+)-α-pinene. The relative abundances of Lactococcus (Lactobacillales: Streptococcaceae) and Lelliottia (Enterobacteriales: Enterobacteriaceae) increased drastically with R -(+)-α-pinene and S -(–)-α-pinene treatment, respectively. This indicated a distinct enantiomer-specific effect of α-pinene on the I. typographus gut bacteria. This study demonstrated the plasticity of gut bacteria during I. typographus development, when α-pinene host monoterpenes are encountered. This study provides new insights into the relationship between ' I. typographus –gut bacteria' symbionts and host trees. [ABSTRACT FROM AUTHOR]

A deteriorated water quality is closely associated with disease outbreaks in aquaculture, where microorganisms play indispensable roles in improving water quality and aquatic animals' health. Mangrove is known to be a natural water quality filter and microbiological buffer of pathogen and prebiotics. However, it is unclear how and to what extent Rhizophora apiculata plantation is of benefits to the gut microbiota and growth over mud crab (Scylla paramamosain) aging. To address these concerns, we explored the bacterial communities in mud crab gut and rearing water at 45, 114, and 132 days after incubation, roughly corresponding to juvenile, pre-adult, and adult stages of mud crab. Results showed that 1-year R. apiculata plantation slightly increased the body weight of mud crab and improved water quality to a certain extent. Both bacterioplankton and gut bacterial communities were highly temporal dynamic, while the two communities were significantly distinct (ANOSIM r = 0.90, P = 0.0001). Relative abundances of dominant taxa in water and gut significantly varied between the plantation and the control conditions over mud crab aging. R. apiculata plantation promoted the stability of gut microbiota, as evidenced by more diverse core species. Furthermore, R. apiculata plantation led to the dominance of Verrucomicrobiae species in water and probiotic Bacteroidetes and Lactobacillales taxa in gut. A structural equation model revealed that water variables directly constrained gut microbiota, which in turn affected the body weight of mud crab (r = 0.52, P < 0.001). In addition, functional pathways facilitating immunity and lipid metabolism significantly increased in mud crab gut under the plantation, while those involved in infectious diseases exhibited the opposing trend. These findings greatly expand our understanding of the R. apiculata plantation effects on water quality, gut microbiota, and growth feature of mud crab. Overall, R. apiculata plantation is beneficial for mud crab growth and health. Key Points: • A short-term R. apiculata plantation could potentially improve water quality. • Bacterioplankton is more sensitive than mud crab gut microbiota in response to R. apiculata plantation. • R. apiculata plantation enhances mud crab resistance against pathogen invasion. • R. apiculata plantation alters mud crab gut microbiota, which in turn promotes their body weight. [ABSTRACT FROM AUTHOR]

The assembly of host-associated bacterial communities is influenced by a multitude of biotic and abiotic factors. It is essential to gain insight in the impact and relative strength of these factors if we want to be able to predict the effects of environmental change on the assembly of host-associated bacterial communities, or deliberately modify them. The environmental pool of bacteria, from which the host is colonized, and the genetic background of the host are both considered to be important in determining the composition of host-associated bacterial communities. We experimentally assessed the relative importance of these two factors and their interaction on the composition of Daphnia magna gut bacterial communities. Bacterioplankton originating from natural ponds or a laboratory culture were used to inoculate germ-free Daphnia of different genotypes. We found that the composition of the environmental bacterial community has a major influence on the Daphnia gut bacterial community, both reflected by the presence or absence of specific taxa as well as by a correlation between abundances in the environment and on the host. Our data also indicate a consistent effect of host genotype on the occurrence of specific bacterial taxa in the gut of Daphnia over different environments. [ABSTRACT FROM AUTHOR]

Sucrose-based biofloc system could facilitate the growth and fitness of shrimp (Penaeus vannamei) by regulating the gut bacterial community. However, little is known about the specific taxa enriched by sucrose-based biofloc system that could improve shrimp health. Here, we investigated the influences of sucrose-based biofloc system on the diversity, structure, and function of the shrimp gut bacterial community. Sucrose-based biofloc system enhanced the observed species and shannon index of the gut bacterial community, and altered the bacterial community compositions by aggrandizing the relative abundances of Amaricoccus , Demequina , and Microbacterium , and decreasing the abundances of potential pathogens belonging to Mycoplasmataceae. The relative abundances of three key operational taxonomic units (OTUs), Demequina OTU465, Microbacterium OTU778, and Amaricoccus OTU 3213 accounted for >50% contributions to shrimp growth and survival rate. Sucrose-based biofloc system positively improved the bacterial community functions involved in amino acid metabolism, metabolism of terpenoids and polyketides, and carbohydrate metabolism. These improved functions were also positively associated with these key OTUs, further implying that they might be key for shrimp health. Finally, the corresponding strains of these key OTUs were isolated to construct a synthetic community, which showed significantly promotive role in shrimp growth and resistance against pathogen challenge. These results not only help us understand the role of sucrose-based biofloc system in improving shrimp fitness better but also provide a reference for suppressing disease occurrence through the use of bacterial inocula. • Sucrose addition changed the bacterial community diversity and structure. • Sucrose addition directly enriched some specific taxa in the shrimp gut. • Specifically enriched taxa had great contributions on shrimp growth and survival rate. • Sucrose addition altered the potential functions of shrimp gut bacterial community. • Combination of specifically enriched bacteria protected shrimp against Vibrio challenge. [ABSTRACT FROM AUTHOR]

Host gut bacterial community has strong resistance to the invasion of pathogens. However, the specific gut taxa that could confer the resistance against pathogens in shrimp are largely unknown. Here, we demonstrated that the shrimp in the same tank showed different resistance after pathogenic Vibrio parahaemolyticus challenge. Subsequently, the gut bacterial communities of healthy, diseased, and moribund shrimp were analyzed. The results indicated that the gut bacterial community in the healthy shrimp still kept a high stability after challenge, while they were gradually disordered with the severity of disease in the diseased, and moribund shrimp. Certain specific taxa belonging to Rhodobacteraceae (e.g., Ruegeria , Paracoccus , Sulfitobacter , and Phaeobacter), Flavobacteriaceae (e.g., Tenacibaculum) and Demequinaceae (e.g., Demequina) were mainly depleted in the moribund shrimp, compared to that in healthy, and diseased shrimp. Seven corresponding strains of above specific taxa including five Rhodobacteraceae, one Tenacibaculum and one Demequina were isolated from the shrimp gut. Then, four different synthetic communities (SynComs) were constructed by using these isolates: SynComA, all five strains from Rhodobacteraceae; SynComB, SynComA + T. lutimaris HBG23; SynComC, SynComA + D. globuliformis TCG4; and SynComD, SynComA + T. lutimaris HBG23 + D. globuliformis TCG4. The addition of these SynComs could not only improve the fitness of shrimp, but also protect them against subsequent V. parahaemolyticus challenge, especially the addition of SynComD. Our study revealed that specific gut bacteria inhabited in healthy shrimp could improve shrimp resistance against pathogenic microbes. • Shrimp in the same box showed different resistance after Vibrio challenge. • Gut bacterial communities of healthy, diseased and moribund shrimp differed. • Specific taxa were almost depleted in moribund shrimp but not in diseased shrimp. • SynComs were constructed by using the corresponding isolates of above specific taxa. • Addition of SynComs protected the shrimp against Vibrio challenge. [ABSTRACT FROM AUTHOR]

The bacterial communities in the gut of an insect have important ecological and functional effects on the insect. However, the community composition and diversity of the gut microbiota in insects that vector plant viruses are poorly understood. As an important insect vector, Psammotettix alienus transmits various viruses including wheat dwarf virus (WDV). Here, we used the combination of leafhopper and WDV as model to survey the influence of gut microbiota on virus transmission characteristic of insect vector and vice versa. We have characterized 22 phyla and 249 genera of all gut bacterial communities in the leafhopper populations collected from six geographic regions in China. Community composition and diversity varied across different geographic populations. However, WDV transmission efficiencies of these six field populations were all greater than 80% with no significant difference. Interestingly, the transmission efficiency of WDV by laboratory reared insects with decreased gut bacterial diversity was similar to that of field populations. Furthermore, we found that the composition of the leafhopper gut bacteria was dynamic and could reversibly respond to WDV acquisition. Higher bacterial diversity and abundance of gut microbiota in different leafhopper populations did not influence their WDV transmission efficiency, while the acquisition of WDV changes gut microbiota by a dynamic and reversible manner. This report provides insight into the complex relationship between the gut microbiota, insect vector and virus.