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Prodigiosin finds tremendous application in the food industry owing to its physicochemical and non-toxic attributes. In the present investigation, microbial production of food color (prodigiosin) was done by Serratia marcescens NCIM 5246 under solid-state fermentation (SSF). For economical prodigiosin yield, initial substrate screening was conducted using agro-waste such as rice bran, wheat bran, orange peel powder, green gram husk and cane molasses. A maximum pigment yield of 1059.67 ± 1.53 µg/L was observed on wheat bran media. Further, Taguchi Design of the experiment (DOE) using Qualitek-4 software with bigger is better as quality attributes was done for process optimization. The Taguchi (DOE) comprised five independent variables, i.e., pH, temperature, substrate concentration, trace metal concentration, and inoculum size at two levels. The software deduced independent variables' individual and interactive effects on product yield by performing an L8 orthogonal array (OA). The output variable (prodigiosin yield) was improved based on the S/N ratio. Under optimized cultural conditions maximum prodigiosin yield of 1320.2 ± 20 µg/L was obtained. The expected prodigiosin yield of 1386.60 µg/L showed a 95% resemblance with the actual yield, showed model validation, and 24.57% improvement in overall yield. The extracted pigment was purified by TLC and was characterized as prodigiosin by absorption spectroscopy and FTIR. [ABSTRACT FROM AUTHOR]

BACKGROUND: Electrochemically active bacteria (EAB) capable of bidirectional extracellular electron transfer (EET), either outward or inward EET, largely control the efficiency of interactions and electrical communication between biofilm and electrode and, thus, control the performance of bioelectrochemical systems (BESs) for heavy metals removal. However, the behavior of such metallurgical EAB capable of bidirectional EET has yet to be investigated, and the role of extracellular polymeric substances (EPS) in these switchable EAB with bidirectional EET and in the presence of heavy metals remains unexplored in the single‐chamber BESs treating heavy metal‐based wastewaters that are limited by carbon/electron sources or electron acceptors. RESULTS: The biofilms of the Cr(VI)‐tolerant EAB Stenotrophomonas sp. YS1 and Serratia marcescens Q1 exhibited bidirectional EET metabolizing either organic (acetate) or inorganic (HCO3−) species with simultaneous removal of Cr(VI) in single‐chamber BESs. Q1 inward EET uptake of electrons was more efficient than that of YS1 (165 μA vs. 118 μA); meanwhile, YS1 outward EET was more efficient than Q1 (8.0 μA vs. 4.7–5.2 μA). The adaptive electrochemically‐tunable EPS in both biofilm strains was regulated by the direction of the EET (inward or outward) in the presence of Cr(VI) and circuital current. CONCLUSION: This study demonstrates the switching properties of EAB, such as Stenotrophomonas sp. or S. marcescens, that are capable of bidirectional EET to or from the electrodes, and it displays the regulation of such responses with the amount and compositional diversity of the biofilms' EPS, giving a comprehensive appreciation of tunable EPS for Cr(VI)‐wastewater treatment in single‐chamber BESs. © 2024 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

Background: Dengue is the most re-emergent infection, with approximately 100 million new cases reported annually, yet no effective treatment or vaccine exists. Here, we aim to define the microbial community structure and their functional profiles in the dengue positive patients with varying disease severity. Methodology/Principal findings: Hospital admitted 112 dengue-positive patients blood samples were analyzed by dual RNA-sequencing to simultaneously identify the transcriptionally active microbes (TAMs), their expressed genes and associated pathways. Results highlight that patients with severe dengue exhibited increased microbial diversity and presence of opportunistic species (unique and core) which includes Bacillus cereus, Burkholderia pseudomallei, Streptococcus suis, and Serratia marcescens. The functional profile analysis revealed enriched metabolic pathways such as protein degradation, nucleotide biosynthesis, ion transport, cell shape integrity, and ATP formation in severe cases, indicating the high energy demands and adaptability of these microbes. Conclusion: Our metatranscriptomic approach provides a species-level characterization of blood microbiome composition and reveals a heightened diversity of TAMs in patients with severe dengue, underscoring the need for further research into the role of blood microbiota in disease progression. Comparing the microbial signatures across the severity classes early in the disease offers unique potential for convenient and early diagnosis of dengue infection. Author summary: Dengue poses a significant public health challenge in tropical and subtropical regions. The lack of a specific treatment or broadly effective vaccine highlights the critical need for novel approaches. In this study, we investigated the transcriptionally active microbial species (TAMs) in 112 dengue-positive patients from MAX Hospital in Delhi, India, to identify their correlations with disease severity. RNA-seq analysis revealed an increased abundance of opportunistic TAMs in severe dengue patients, with some species showing significant associations with platelet counts and total leukocyte count (TLC). Our findings underscore the underappreciated importance of the blood microbiome in dengue, particularly the heightened metabolic activity of these opportunistic species in severe cases. This study offers valuable insights for early infection diagnosis for dengue management. The species-level data identified here could pave the way for systematic exploration of microbial involvement in dengue virus (DENV) infections, potentially serving as an indicator for new adjuvant treatment strategies. [ABSTRACT FROM AUTHOR]

Mutualistic relationships with photosynthetic organisms are common in cnidarians, which form an intracellular symbiosis with dinoflagellates in the family Symbiodiniaceae. The establishment and maintenance of these symbionts are associated with the suppression of key host immune factors. Because of this, there are potential trade-offs between the nutrition that cnidarian hosts gain from their symbionts and their ability to successfully defend themselves from pathogens. To investigate these potential trade-offs, we utilized the facultatively symbiotic polyps of the upside-down jellyfish Cassiopea xamachana and exposed aposymbiotic and symbiotic polyps to the pathogen Serratia marcescens. Symbiotic polyps had a lower probability of survival following S. marcescens exposure. Gene expression analyses 24 hours following pathogen exposure indicate that symbiotic animals mounted a more damaging immune response, with higher levels of inflammation and oxidative stress likely resulting in more severe disruptions to cellular homeostasis. Underlying this more damaging immune response may be differences in constitutive and pathogen-induced expression of immune transcription factors between aposymbiotic and symbiotic polyps rather than broadscale immune suppression during symbiosis. Our findings indicate that in facultatively symbiotic polyps, hosting symbionts limits C. xamachana's ability to survive pathogen exposure, indicating a trade-off between symbiosis and immunity that has potential implications for coral disease research. [ABSTRACT FROM AUTHOR]

The honey bee, Apis mellifera L., is one of the main pollinators worldwide. In a temperate climate, seasonality affects the life span, behavior, physiology, and immunity of honey bees. In consequence, it impacts their interaction with pathogens and parasites. In this study, we used Bayesian statistics and modeling to examine the immune response dynamics of summer and winter honey bee workers after injection with the heat-killed bacteria Serratia marcescens, an opportunistic honey bee pathogen. We investigated the humoral and cellular immune response at the transcriptional and functional levels using qPCR of selected immune genes, antimicrobial activity assay, and flow cytometric analysis of hemocyte concentration. Our data demonstrate increased antimicrobial activity at transcriptional and functional levels in summer and winter workers after injection, with a stronger immune response in winter bees. On the other hand, an increase in hemocyte concentration was observed only in the summer bee population. Our results indicate that the summer population mounts a cellular response when challenged with heat-killed S. marcescens, while winter honey bees predominantly rely on humoral immune reactions. We created a model describing the honey bee immune response dynamics to bacteria-derived components by applying Bayesian statistics to our data. This model can be employed in further research and facilitate the investigating of the honey bee immune system and its response to pathogens. [ABSTRACT FROM AUTHOR]

Bacteria are major drivers of organic matter decomposition and play crucial roles in global nutrient cycling. Although the degradation of dead fungal biomass (necromass) is increasingly recognized as an important contributor to soil carbon (C) and nitrogen (N) cycling, the genes and metabolic pathways involved in necromass degradation are less characterized. In particular, how bacteria degrade necromass containing different quantities of melanin, which largely control rates of necromass decomposition in situ, is largely unknown. To address this gap, we conducted a multitimepoint transcriptomic analysis using three Gram-negative, bacterial species grown on low or high melanin necromass of Hyaloscypha bicolor. The bacterial species, Cellvibrio japonicus, Chitinophaga pinensis, and Serratia marcescens, belong to genera known to degrade necromass in situ. We found that while bacterial growth was consistently higher on low than high melanin necromass, the CAZyme-encoding gene expression response of the three species was similar between the two necromass types. Interestingly, this trend was not shared for genes encoding nitrogen utilization, which varied in C. pinensis and S. marcescens during growth on high vs low melanin necromass. Additionally, this study tested the metabolic capabilities of these bacterial species to grow on a diversity of C and N sources and found that the three bacteria have substantially different utilization patterns. Collectively, our data suggest that as necromass changes chemically over the course of degradation, certain bacterial species are favored based on their different ial metabolic capacities. IMPORTANCE Fungal necromass is a major component of the carbon (C) in soils as well as an important source of nitrogen (N) for plant and microbial growth. Bacteria associated with necromass represent a distinct subset of the soil microbiome and characterizing their functional capacities is the critical next step toward understanding how they influence necromass turnover. This is particularly important for necromass varying in melanin content, which has been observed to control the rate of necromass decomposition across a variety of ecosystems. Here we assessed the gene expression of three necromass-degrading bacteria grown on low or high melanin necromass and characterized their metabolic capacities to grow on different C and N substrates. These transcriptomic and metabolic studies provide the first steps toward assessing the physiological relevance of up-regulated CAZyme-encoding genes in necromass decomposition and provide foundational data for generating a predictive model of the molecular mechanisms underpinning necromass decomposition by soil bacteria. [ABSTRACT FROM AUTHOR]

Urease-producing bacteria (UPB) are widely present in soil and play an important role in soil ecosystems. In this study, 65 UPB strains were isolated from cadmium (Cd)-polluted soil around a lead-zinc mine in Yunnan Province, China. The Cd tolerance, removal of Cd from aqueous solution, production of indoleacetic acid (IAA) and plant growth-promoting effects of these materials were investigated. The results indicate that among the 65 UPB strains, four strains with IAA-producing ability were screened and identified as Bacillus thuringiensis W6-11, B. cereus C7-4, Serratia marcescens W11-10, and S. marcescens C5-6. Among the four strains, B. cereus C7-4 had the highest Cd tolerance, median effect concentration (EC50) of 59.94 mg/L. Under Cd 5 mg/L, S. marcescens C5-6 had the highest Cd removal from aqueous solution, up to 69.83%. Under Cd 25 mg/kg, inoculation with B. cereus C7-4 significantly promoted maize growth in a sand pot by increasing the root volume, root surface area, and number of root branches by 22%, 29%, and 20%, respectively, and plant height and biomass by 16% and 36%, respectively, and significantly increasing Cd uptake in the maize roots. Therefore, UPB is a potential resource for enhancing plant adaptability to Cd stress in plants with Cd-polluted habitats. STATEMENT OF NOVELTY: This study utilized urease-producing bacteria screened from the soil of lead zinc mining areas in Yunnan, China as the research object, enriching the microbial resources in Yunnan. In addition, this article verified the IAA production ability and cadmium removal ability of urease-producing bacteria, and screened out bifunctional urease-producing bacteria that have potential in cadmium pollution control and plant growth promotion. [ABSTRACT FROM AUTHOR]

Improving food preservation technologies is a key aspect in the struggle to reduce global food waste, and natural antimicrobial substances, such as essential oil (EO) components represent very promising food preserving agent. However, their intrinsic chemico‐physical properties, such as the low melting point, low water solubility and high volatility, pose some practical difficulties in exploiting them for practical applications. Cocrystallization is used to stabilize liquid or volatile EO components providing them whit a crystalline environment, thus improving their potential application as antibacterial agents. Five EO active ingredients (THY = thymol, CAR = carvacrol, EUG = eugenol, CAD = trans‐cinnamaldehyde, and VAN = o‐vanillin) and two coformers (INA = Isonicotinamide, and HBA = 4‐hydroxybenzoic acid) have been combined and the corresponding cocrystals have been studied for their potential inhibiting effect against four food spoilage bacteria (Bacillus thuringiensis, Enterobacter cloacae, Pseudomonas fluorescens, and Serratia marcescens). The structures of the five cocrystals have been used to derive structure‐activity relationships in terms of release energy of the active ingredients form the crystalline environment, and a correlation has been derived with the Intermolecular Interaction Energies of the EO molecules. [ABSTRACT FROM AUTHOR]

Lipases are hydrolytic enzymes which have significant potential for commercial applications, particularly in the breakdown of oil contaminants. Serratia marcescens EGHK-19 isolate exhibited considerable lipase activity. This study investigates the optimization, purification, and characterization of lipase from the Serratia marcescens EGHK-19 isolate. The optimized culture conditions revealed that maximal lipase activity was achieved after 24 hours at 30°C and pH 7, with continuous shaking at 150 rpm. Utilizing a 2% inoculum percentage with 1% diesel and 0.3% tryptone in the presence of Fe2+, Ca2+, Mg2+ salts, and Tween 80 resulted in the highest activity at 17.278 U/ml/min. The purification process involved acetone precipitation and DEAE-Sephadex column chromatography, revealing a molecular weight of approximately 60 kDa on SDS-PAGE. This method exhibited a 0.985-fold purification, and the final yield was limited to 2.097% due to lipase aggregates. Characterization of the purified lipase indicated optimal activity (8.765 U/mL/min) at 40°C a nd p H 7. T he K m a nd V max values w ere c alculated a s 6 .89 m M a nd 6 5.79 µmol/min, respectively. The presence of SDS, Tween 80, and Triton X-100 surfactants resulted in the inhibition of lipase activity. Despite these insuggestss, the biochemical characteristics of the purified lipase suggest its potential as an excellent candidate for various industrial applications. [ABSTRACT FROM AUTHOR]

Effects of heavy metals on soil microbial communities have been extensively studied due to their persistence in the environment and imposed threats to living organisms; however, there is a lack of in-depth studies of the impacts of heavy metals on plant endophyte communities. Therefore, the responses of plant endophyte communities to different concentrations of heavy metals were investigated in this study. The endophyte communities of plants existing in severely (W1, Pb, 110.49 mg/kg, Cd, 1.11 mg/kg), moderately (W2, Pb, 55.06 mg/kg, Cd, 0.48 mg/kg), and mildly (W3, Pb, 39.06 mg/kg, Cd, 0.20 mg/kg) contaminated soils were analyzed by 16s rRNA high-throughput Illumina sequencing. Furthermore, networks were constructed to illustrate the relationships between microorganisms and environmental factors. High-quality sequences were clustered at a 97% similarity level. Results revealed that the diversity of the community and relative abundance of Cyanobacteria phylum increased with decreasing levels of pollution. Cyanobacteria and Proteobacteria were found to be the dominant phylum, while Methylobacterium and Sphingomonas were observed as the dominant genus. Tukey's HSD test showed that the relative abundances of Cyanobacteria and Proteobacteria phyla and Methylobacterium and Sphingomonas genera differed significantly (p < 0.01) among the plants of the three sample sites. Environmental factor analysis revealed a significant negative correlation (p < 0.01) of Cyanobacteria and a significant positive correlation (p < 0.01) of Methylobacterium with the heavy metal content in the environment. These findings suggest that Cyanobacteria and Methylobacterium may be phylum and genus indicators, respectively, of heavy metal toxicity. Tax4Fun analysis showed the effect of heavy metal toxicity on the abundance of genes involved in plant metabolism. In addition, culturable endophytic strains were isolated to study their resistance to heavy metal stress and their ability to promote plant growth. The potting tests showed that the JG1 strain was tolerant to heavy metals, and it could significantly promote the growth of the host plant under stress caused by multiple heavy metals. Compared to the control, the JG1-treated plants showed a 23.14% increase in height and a 12.84% increase in biomass. Moreover, AP, AK, and HN contents in JG1-treated plants were 20.87%, 12.55%, and 9.03% higher, respectively, under heavy metal stress. The results of this study provide a scientific basis for the construction of an efficient plant endophyte restoration system. [ABSTRACT FROM AUTHOR]

BACKGROUND AND OBJECTIVES: Zinc deficiency is a significant global health concern, affecting around two billion people due to insufficient dietary intake. The extensive utilization of cereal-based meals with inadequate zinc content and limited bioavailability stands as the primary cause for this issue. Children who possess low levels of zinc experience stunted growth and developmental delays. They also have higher rates of morbidity from pneumonia, diarrhoea, and malaria. Inadequate zinc intake has been correlated with a heightened risk of mortality in children due to specific diseases. It is crucial to secure a satisfactory level of zinc in rice grains because of its indispensable function in various biochemical processes that are fundamental for the growth and advancement of plants. A deficiency in zinc can lead to reduced grain yield and nutritional value in rice. Recently, the utilization of registered biofertilizers and microbial technology is widely recognized in contemporary intensive farming practices. Some indigenous zinc-solubilizing bacterial strains discovered can increase rice yield and zinc content in grains. The objective of this study was to impact of a biofertilizer formula consisting of native zinc solubilizer strains on the growth, productivity, and zinc concentration in the grains of three rice varieties, namely Inpari IR Nutrizinc, Inpari 48, and Inpago 13 Fortiz. The study was conducted in a paddy field located in the Inceptisol of Subang Regency, West Java, during the year 2023. METHODS: The field trial was conducted to study the impact of a biofertilizer comprising a group of non-pathogenic zinc-solubilizing bacteria, including Enterobacter cloacae, Klebsiella pneumoniae, Serratia marcescens, Bacillus thuringiensis, and Enterobacter bugandensis on rice growth, yield, zinc levels, and uptake in grains. The rhizosphere soils were the origin of these bacteria, which were obtained using agar media containing zinc oxide as insoluble zinc compounds. Prior to this, the bacterial strains were evaluated for their capacity to dissolve zinc and generate the plant hormone indole-3-acetic acid. To gauge their zinc-solubilizing prowess, Pikovskaya agar media, supplemented with insoluble zinc oxide and calcium phosphate, respectively, were utilized. The presence of distinct clear areas surrounding the colonies demonstrated the effectiveness of the microbes in converting insoluble zinc and phosphorus into soluble forms. The concentration of the plant hormone indole-3-acetic acid was measured using the Salkowski reagent. The field trial was organized using a split-plot design with three replications. The application of the biofertilizer mixture as a seed treatment was carried out before the transplantation of the rice nursery. The seedlings were prepared individually for each rice variety, with a comparison made between those treated with the biofertilizer and those that were not. FINDINGS: The study found that the consortium of indigenous non-pathogenic zinc-solubilizing bacteria significantly increased the yield of rice varieties by about 5.6 percent and zinc content in grains by 16.3 percent. However, the application of zinc containing fertilizer treatments did not enhance the rice yield and zinc content in grains in this Inceptisol paddy soil. In terms of zinc content in grains, the rice variety Inpago 13 Fortiz exhibited a notable increase compared to the Inpari IR Nutrizinc variety, with levels of 40.3 milligrams per kilogram as opposed to 34.1 milligrams per kilogram. CONCLUSION: the utilization of a native combination of carefully chosen zinc-solubilizing bacterial strains could augment the productivity, zinc concentration, and absorption in rice grains of various varieties in a paddy field with Inceptisols soil type, characterized by a moderate to high overall zinc content and limited zinc accessibility. The addition of zinc containing fertilizer treatments did not enhance rice yield compared to the addition of other tratments or control. This is probably because of the medium-high level of the total zinc content of the soil, suggesting that the addition of Biofertizinc will reduce or delete the crop requirement for zinc fertilizer in Inceptisol paddy fields. This implies that the biofertilizer is ecologically sustainable as it eliminates the use of harmful chemicals, reduces the reliance on synthetic fertilizers, and lowers costs. [ABSTRACT FROM AUTHOR]

Endophytic fungi are known to be a rich source for anti-infective drugs. In this study, Aptenia cordifolia associated endophytic fungi were explored for the first time. Seven isolates were identified morphologically followed by screening of these fungi by plug diffusion assay which revealed their potential activity against Staphylococcus aureus (ATCC 9144), Bacillus cereus (ATCC 14579), Serratia marcescens (ATCC 14756), Fusarium oxysporum (ATCC 48112), and Aspergillus flavus (ATCC 22546). Additionally, the crude ethyl acetate extract of the most potent three isolates in plug diffusion assay showed that Aspergillus sp. ACEFR2 was the most potent as anti-infective in disc diffusion assay; Accordingly, Aspergillus sp. ACEFR2 was investigated using phylogenetic analysis and LC-HR-ESI-MS. The phylogenetic analysis placed the strain into the Aspergillus section Niger close related to few species including A. niger. Whereas the metabolomic profiling revealed the presence of diverse pool of metabolites. Furthermore, in silico molecular docking study was carried out to predict which compounds most likely responsible for the anti-infective activity. [ABSTRACT FROM AUTHOR]

The study successfully produced a hybrid nanocomposite of silver nanoparticles embedded with end-of-life battery-derived sheets-like nitrogen and sulfur-doped reduced-graphene oxide (AgNPs@NSG), which was utilized to remove methylene blue (MB) and paracetamol (PC) from aqueous solutions. The AgNPs@NSG nanocomposite was analyzed using various techniques. Several conditions, including pH value, adsorbent dose, initial concentration, and contact time, were studied to improve the removal efficiency of MB and PC. The pseudo-second-order model was the best fit for both MB and PC adsorption kinetics. The Langmuir model effectively described the experimental data for the adsorption isotherm, with maximum adsorption capacities of 61.72 and 52.6 mg/g for MB and PC, respectively, at room temperature. Additionally, the AgNPs@NSG nanocomposite demonstrated promising antibacterial activity against Gram-positive and Gram-negative bacteria. The nanocomposite showed inhibition zone diameters of 12.00 mm for Bacillus subtilis, 10.33 mm for Staphylococcus aureus, 9.67 mm for Streptococcus mutans, 10.00 mm for Escherichia coli, 11.33 mm for Proteus vulgaris, 9.67 mm for Serratia marcescens, and 10.67 mm for Vibrio parahaemolyticus. These results indicate the potential of AgNPs@NSG for reducing microorganism infections, especially in wastewater treatment. Overall, this study presents a simple and cost-effective process for producing an efficient material to remove harmful pollutants from wastewater. It also demonstrates its additional antimicrobial properties, highlighting its potential for versatile applications in environmental cleanup and infection control. [ABSTRACT FROM AUTHOR]

ABSTRACT Background Aims Patients/Methods Results Conclusions The field of cosmetic filler injection has experienced rapid development over the past two decades, especially in facial augmentation utilizing hyaluronic acid (HA) fillers. Gram‐negative bacteria are found to be the main pathogens of infective nodules after HA injection. The occurrence of cutaneous infections attributed to Serratia marcescens is exceedingly rare and predominantly noted in patients with compromised immune systems.To summarize the clinical features, diagnosis, and treatment of subcutaneous infection caused by Serratia marcescens following hyaluronic acid injection.A rare case of cutaneous Serratia marcescens infection following hyaluronic acid injection was presented. A comprehensive review of the published literature describing the management of skin infection caused by S. marcescens in immunocompetent patients was then conducted, which encompassed three case series and eight case reports published between 1999 and 2017. Data extraction included information on authors, gender, age, signs and symptoms, previous treatment, corresponding management strategies, and follow‐up duration.Serratia marcescens were isolated in abscesses (n = 6, 35.29%), painful nodules (n = 2, 11.76%), ulcers (n = 6, 35.29%), and others (n = 3, 17.65%). In cases providing salvage plans (n = 11), quinolones were shown to be the most effective antibiotics for salvage, with eight full recoveries (72.73%), and trimethoprim‐sulfamethoxazole was the second most useful antibiotic (18.18%).With the help of pathogen examination and drug‐sensitive tests, sensitive aminoglycosides, quinolone (especially moxifloxacin), or TMP‐SMX for at least 2 weeks can be considered as the first‐line treatment of late subcutaneous infection caused by Serratia marcescens following hyaluronic acid injection. [ABSTRACT FROM AUTHOR]

Biofilms currently represent the most prevalent bacterial lifestyle, enabling them to resist environmental stress and antibacterial drugs. Natural antibacterial agents could be a safe solution for controlling bacterial biofilms in food industries without affecting human health and environmental safety. A methanolic extract of Azadirachta indica (neem) leaves was prepared and analyzed using gas chromatography–mass spectrometry for the identification of its phytochemical constituents. Four food-borne bacterial pathogens (Bacillus cereus, Novosphingobium aromaticivorans, Klebsiella pneumoniae, and Serratia marcescens) were tested for biofilm formation qualitatively and quantitatively. The antibacterial and antibiofilm properties of the extract were estimated using liquid cultures and a microtiter plate assay. The biofilm inhibition mechanisms were investigated using a light microscope and molecular docking technique. The methanolic extract contained 45 identified compounds, including fatty acids, ester, phenols, flavonoids, terpenes, steroids, and antioxidants with antimicrobial, anticancer, and anti-inflammatory properties. Substantial antibacterial activity in relation to the extract was recorded, especially at 100 μg/mL against K. pneumoniae and S. marcescens. The extract inhibited biofilm formation at 100 μg/mL by 83.83% (S. marcescens), 73.12% (K. pneumoniae), and 54.4% (N. aromaticivorans). The results indicate efficient biofilm formation by the Gram-negative bacteria S. marcescens, K. pneumoniae, and N. aromaticivorans, giving 0.74, 0.292, and 0.219 OD at 595 nm, respectively, while B. cereus was found to have a low biofilm formation potential, i.e., 0.14 OD at 595 nm. The light microscope technique shows the antibiofilm activities with the biofilm almost disappearing at 75 μg/mL and 100 μg/mL concentrations. This antibiofilm property was attributed to DNA gyrase inhibition as illustrated by the molecular docking approach. [ABSTRACT FROM AUTHOR]

Aims To construct an efficient bacterial complex to degrade nicosulfuron and clarify its degradative characteristics, promote the growth of maize (Zea mays), and provide a theoretical foundation for the efficient remediation of soil contaminated with nicosulfuron. Methods and results Biocompatibility was determined by the filter paper sheet method by mixing Serratia marcescens A1 and Bacillus cereus A2 in a 1:1 ratio, yielding A12. The optimum culture conditions for the bacterial composite were obtained based on a three-factor, three-level analysis using response surface methodology, with 29.25 g l−1 for maltodextrin, 10.04 g l−1 for yeast extract, and 19.93 g l−1 for NaCl, which resulted in 92.42% degradation at 4 d. The degradation characteristics of A12 were clarified as follows: temperature 30°C, pH 7, initial concentration of nicosulfuron 20 mg l−1, and 4% inoculum. The ability to promote growth was determined by measuring the ratio of the lysosphere diameter (D) to the colony diameter (d), and the ability of the complex A12 to promote growth was higher than that of the two single strains. Conclusions Nicosulfuron degradation in sterilized and unsterilized soils reached 85.4% and 91.2% within 28 d, respectively. The ability of the strains to colonize the soil was determined by extraction of total soil DNA, primer design, and gel electrophoresis. The bioremediation effect of A12 was confirmed by the maximum recovery of fresh weight (124.35%) of nicosulfuron-sensitive crop plants and the significant recovery of soil enzyme activities, as measured by the physiological indices in the sensitive plants. [ABSTRACT FROM AUTHOR]

Trichomonas vaginalis and associated bacteria are important urogenital pathogens. This study aimed to investigate the effect of T. vaginalis and its associated bacteria on semen and sperm parameters related to male fertility. Urine and semen samples were collected from 97 males, whose ages between 18-50 years. Semen and sperm parameters, such as semen volume, sperm count, sperm concentration, sperm motility, leucocytes/pus cells, and erythrocytes, were evaluated according to the WHO instructions. Conventional-PCR and real-time quantitative PCR were used to detect T. vaginalis infection. Amie's-transport, blood-agar, MacConkey-agar, Chocolate-agar, Thayer-Martin-agar, and Mannitol-salt-agar were used to culture bacteria in urine, and the Vitek2 system was used to differentiate bacteria. Samples that showed positive microscopic examination for bacteria but were not culturable were diagnosed using PCR. T. vaginalis and bacterial infection rates were 31.8% and 17.5%, respectively. T. vaginalis, bacteria, and both together caused a decrease in some qualitative and quantitative parameters of semen and sperm such as a decline in sperm total count by 46.5, 63.46, and 65.67% respectively, sperm concentration by 6.27, 15.37, and 44.27% respectively, sperm motility by 67.63, 66.18 and 66.75% respectively, semen volume by 42.2, 36.4 and 63.86% respectively. They caused increases of 100.92, 16.89, and 84.56%, respectively, and sperm death by 36.58, 80.0%, 93%, and 60.77%, respectively. In addition, they caused an increase in WBCs/pus cells and RBCs in the semen and urine. Four bacteria species, Pantoea spp., Sphingomonas paucimobilis, Staphylococcus aureus, Methylobacterium spp. were detected in urine, and 10 species, Enterobacter aerogenes, Serratia marcescens, Pseudomonas putida, Sphingomonas paucimobilis, Aeromonas sobria, Burkholderia cepacia, Staphylococcus aureus, Aerococcus viridans, Pseudomonas androgens and Staphylococcus epidermidis were detected in semen. In addition, PCR identified three unculturable species: one in urine (Holomonas spp.), and two in semen (Lactobacillus jensenii and Holomonas spp.), S. aureus had the highest frequency in urine and semen of (32%). [ABSTRACT FROM AUTHOR]

The application of fungicides for commercial purposes has grown in response to increased food demand and shifting disease patterns. However, there is a scarcity of studies demonstrating their proper degradation. Due to the expanding global population, there is a heightened need for more agriculture to fulfill the growing demand for food, and this necessitates safeguarding crops from pests and diseases. Disease outbreaks in crops can result in the loss of food and the depletion of valuable resources. According to the European Union, organic fungicides constitute 60% of all fungicide sales, while synthetic fungicides make up the remaining 40% of pesticide sales. Fungicide usage is indispensable but needs to be considered within the context of potential environmental risks. Nonetheless, there is a pressing need to break down fungicides to preserve the natural environment. Our research is centered on hybrid enzymes derived from S. marcescens, which exhibit the capability to degrade fungicides. We employed computational techniques to assess the enzymes' effectiveness in breaking down fungicides. S. marcescens was isolated from soil and identified through 16s rRNA analysis. Chitanase and lipase, enzymes identified in S. marcescens, can individually break down fungicides, as confirmed by auto-dock vina docking simulations. Notably, the combined action of these two enzymes surpasses the performance of individual docking, a result also corroborated by auto-dock vina. To further establish the efficacy and degradability of this approach, computational techniques were employed. In the future, it may be possible to create an in vitro antifungal agent, which could be categorized as a bioactive agent. Hybrid enzymes derived from Serratia marcescens demonstrate superior fungicide degradation compared to individual enzymes. Computational simulations reveal enhanced effectiveness of combined lipase and chitinase enzymes. This study supports the potential development of in vitro antifungal bioactive agents. [ABSTRACT FROM AUTHOR]

Metallo‐β‐lactamases (MβLs) hydrolyze and inactivate β‐lactam antibiotics, are a pivotal mechanism conferring resistance against bacterial infections. SMB‐1, a novel B3 subclass of MβLs from Serratia marcescens could deactivate almost all β‐lactam antibiotics including ampicillin (AMP), which has posed a serious threat to public health. To illuminate the mechanism of recognition and interaction between SMB‐1 and AMP, various fluorescence spectroscopy techniques and molecular dynamics simulation were employed. The results of quenching spectroscopy unraveled that AMP could make SMB‐1 fluorescence quenching that mechanism was the static quenching; the synchronous and three‐dimensional fluorescence spectra validated that the microenvironment and conformation of SMB‐1 were altered after interaction with AMP. The molecular dynamics results demonstrated that the whole AMP enters the binding pocket of SMB‐1, even though with a relatively bulky R1 side chain. Loop1 and loop2 in SMB‐1 undergo significant fluctuations, and α2 (71–73) and local α5 (186–188) were turned into random coils, promoting zinc ion exposure consistent with circular dichroism spectroscopy results. The binding between them was driven by a combination of enthalpy and entropy changes, which was dominated by electrostatic force in agreement with the fluorescence observations. The present study brings structural insights and solid foundations for the design of new substrates for β‐lactamases and the development of effective antibiotics that are resistant to superbugs. [ABSTRACT FROM AUTHOR]

The healthcare water environment is a potential reservoir of carbapenem-resistant organisms (CROs). To report the role of the water environment as a reservoir and the infection control measures applied to suppress a prolonged outbreak of Klebsiella pneumoniae carbapenemase-producing Serratia marcescens (KPC-SM) in two intensive care units (ICUs). The outbreak occurred in the ICUs of a tertiary hospital from October 2020 to July 2021. Comprehensive patient contact tracing and environmental assessments were conducted, and a case–control study was performed to identify factors associated with the acquisition of KPC-SM. Associations among isolates were assessed via pulsed-field gel electrophoresis (PFGE). Antibiotic usage was analysed. The outbreak consisted of two waves involving a total of 30 patients with KPC-SM. Multiple environmental cultures identified KPC-SM in a sink, a dirty utility room, and a communal bathroom shared by the ICUs, together with the waste bucket of a continuous renal replacement therapy (CRRT) system. The genetic similarity of the KPC-SM isolates from patients and the environment was confirmed by PFGE. A retrospective review of 30 cases identified that the use of CRRT and antibiotics was associated with acquisition of KPC-SM (P < 0.05). There was a continuous increase in the use of carbapenems; notably, the use of colistin has increased since 2019. Our study demonstrates that CRRT systems, along with other hospital water environments, are significant potential sources of resistant micro-organisms, underscoring the necessity of enhancing infection control practices in these areas. [ABSTRACT FROM AUTHOR]

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Microbial infections are a global health challenge often treated with antibiotics, but their overuse can lead to antibiotic resistance. To address this, there is a need for more efficient personal protective equipment (PPE) with novel antimicrobial techniques. One such technique involves using carbon dots (CDs) to create self-disinfecting fabrics. This study focused on synthesizing phenylboronic-acid-functionalized piperine-based carbon dots (PBA-PPCDs) and boronic acid carbon dots (BACDs) as potential antimicrobial agents. The materials were successfully synthesized using a hydrothermal method and characterized using various techniques to confirm the size, charge, fluorescence properties, and inner morphology of the CDs. The CDs showed bactericidal activity against gram-positive and gram-negative bacteria, with potent inhibition in growth especially in the presence of simulated sunlight. The antibacterial properties of the CDs were tested on cellulose discs, demonstrating strong adherence and significant inhibition of bacterial cells. The cytotoxicity studies showed that these CDs, at concentrations up to 0.1 mg/mL, and the CD-modified fibers are benign to mammalian cells, emphasizing their safety for human use. Overall, the study concluded that PBA-PPCDs and BACDs are promising candidates for modifying fibers and inducing antimicrobial activity in fabrics made of cellulose fibers.Article highlights: New self-disinfecting fabrics kill bacteria with light-activated carbon dots, no harsh chemicals needed. Self-disinfecting fabrics fight bacteria, reduce antibiotic use, and slow superbug growth. Safe and effective: Carbon dot fabrics harmless to humans, promising for PPE. [ABSTRACT FROM AUTHOR]

The fruit and vegetable industry in post-harvest processing plants is characterized by a substantial consumption of water resources. Wash waters may serve as an environment for the periodic or permanent habitation of microorganisms, particularly if biofilm forms on the inner walls of tanks and flushing channels. Despite the implementation of integrated food safety monitoring systems in numerous countries, foodborne pathogens remain a global public health and food safety concern, particularly for minimally processed food products such as vegetables and fruits. This necessitates the importance of studies that will explore wash water quality to safeguard minimally processed food against foodborne pathogen contamination. Therefore, the current study aimed to isolate and identify bacteria contaminating the wash waters of four fresh-cut processing plants (Poland) and to evaluate the phenotypic antibiotic resistance profiles in selected species. Bacteria were isolated using membrane filtration and identified through mass spectrometry, followed by antibiotic susceptibility testing according to EUCAST guidelines. The results revealed that the level of contamination with total aerobic bacteria in the water ranged from 1.30 × 106 cfu/mL to 2.54 × 108 cfu/mL. Among the isolates, opportunistic pathogens including Enterococcus faecalis, Pseudomonas aeruginosa, Klebsiella oxytoca, Klebsiella pneumoniae, Serratia marcescens, and Proteus vulgaris strains were identified. An especially noteworthy result was the identification of cefepime-resistant K. oxytoca isolates. These findings highlight the importance of monitoring the microbial microflora in minimally processed foods and the need for appropriate sanitary control procedures to minimize the risk of pathogen contamination, ensuring that products remain safe and of high quality throughout the supply chain. [ABSTRACT FROM AUTHOR]

The aim of this study is to evaluate the antimicrobial susceptibility of invasive isolates of Serratia marcescens , associated with blood stream infections (BSIs) in patients hospitalized in Varna University Hospital, Bulgaria, as well as to identify the genetic mechanisms responsible for 3rd generation cephalosporin and carbapenem-resistance among these isolates. A total of 45 consecutive S. marcescens isolates, obtained from blood cultures of 45 patients with BSIs, hospitalized during an 8-year period (2016–2023) were included. Species identification and antimicrobial susceptibility testing were done by Phoenix (BD, USA) and Vitek 2 (BioMerieux, France) systems and the results were interpreted according to EUCAST guidelines. The genetic mechanisms of beta-lactam resistance were studied by PCR. During the study period, a total of 45 patients were diagnosed with S. marcescens -associated BSIs. All infections were defined as nosocomial, predominantly intensive care unit-acquired (42.2%) and 28.8% were central venous catheter-associated. The following antimicrobial resistance rates were found: ceftriaxone, piperacillin/tazobactam, 57.8%; ceftazidime, 55.6%; cefepime, trimethoprime/sulfamethoxazole, 53.3%; gentamicin, 48.8%; ciprofloxacin, 44.5%; amikacin, 15.6%; carbapenems, 2.2%. The bla CTX-M was identified in 88.9% of the tested 3rd generation cephalosporin resistant isolates. Among these, 50% were also bla TEM positive. The single carbapenem-resistant isolate harboured bla KPC, bla CTX-M1/9, bla CMY-2 and bla TEM. This study demonstrates S. marcescens as a problematic nosocomial pathogen and we report a KPC-producing S. marcescens clinical isolate from a BSI in Bulgaria. [ABSTRACT FROM AUTHOR]

Abstract Quorum sensing (QS) inhibition has emerged as a promising target for directed drug design, providing an appealing strategy for developing antimicrobials, particularly against infections caused by drug‐resistant pathogens. In this study, we designed and synthesized a total of 33 β‐nitrostyrene derivatives using 1‐nitro‐2‐phenylethane (NPe) as the lead compound, to target the facultative anaerobic bacterial pathogen Serratia marcescens. The QS‐inhibitory effects of these compounds were evaluated using S. marcescens NJ01 and the reporter strain Chromobacterium violaceum CV026. Among the 33 new β‐nitrostyrene derivatives, (E)‐1‐methyl‐4‐(2‐nitrovinyl)benzene (m‐NPe, compound 28) was proven to be a potent inhibitor that reduced biofilm formation of S. marcescens NJ01 by 79%. Scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) results revealed that treatment with m‐NPe (50 μg/ml) not only enhanced the susceptibility of the formed biofilms but also disrupted the architecture of biofilms by 84%. m‐NPe (50 μg/ml) decreased virulence factors in S. marcescens NJ01, reducing the activity of protease, prodigiosin, and extracellular polysaccharide (EPS) by 36%, 72%, and 52%, respectively. In S. marcescens 4547, the activities of hemolysin and EPS were reduced by 28% and 40%, respectively, outperforming the positive control, vanillic acid (VAN). The study also found that the expression levels of QS‐ and biofilm‐related genes (flhD, fimA, fimC, sodB, bsmB, pigA, pigC, and shlA) were downregulated by 1.21‐ to 2.32‐fold. Molecular dynamics analysis showed that m‐NPe could bind stably to SmaR, RhlI, RhlR, LasR, and CviR proteins in a 0.1 M sodium chloride solution. Importantly, a microscale thermophoresis (MST) test revealed that SmaR could be a target protein for the screening of a quorum sensing inhibitor (QSI) against S. marcescens. Overall, this study highlights the efficacy of m‐NPe in suppressing the virulence factors of S. marcescens, identifying it as a new potential QSI and antibiofilm agent capable of restoring or improving antimicrobial drug sensitivity.

Host-microbe interactions are virtually bidirectional, but how the host affects their microbiome is poorly understood. Here, we report that the host is a critical modulator to regulate the lifestyle switch and pathogenicity heterogeneity of the opportunistic pathogens Serratia marcescens utilizing the Drosophila and bacterium model system. First, we find that Drosophila larvae efficiently outcompete S. marcescens and typically drive a bacterial switch from pathogenicity to commensalism toward the fly. Furthermore, Drosophila larvae reshape the transcriptomic and metabolic profiles of S. marcescens characterized by a lifestyle switch. More importantly, the host alters pathogenicity and heterogeneity of S. marcescens in the single-cell resolution. Finally, we find that larvae-derived AMPs are required to recapitulate the response of S. marcescens to larvae. Altogether, our findings provide an insight into the pivotal roles of the host in harnessing the life history and heterogeneity of symbiotic bacterial cells, advancing knowledge of the reciprocal relationships between the host and pathogen. [ABSTRACT FROM AUTHOR]

There is a critical gap in knowledge about how Gram-negative bacterial pathogens, using survival strategies developed for other niches, cause lethal bacteremia. Facultative anaerobic species of the Enterobacterales order are the most common cause of Gram-negative bacteremia, including Escherichia coli, Klebsiella pneumoniae, Serratia marcescens, Citrobacter freundii, and Enterobacter hormaechei. Bacteremia often leads to sepsis, a life-threatening organ dysfunction resulting from unregulated immune responses to infection. Despite a lack of specialization for this host environment, Gram-negative pathogens cause nearly half of bacteremia cases annually. Based on our existing Tn-Seq fitness factor data from a murine model of bacteremia combined with comparative genomics of the five Enterobacterales species above, we prioritized 18 conserved fitness genes or operons for further characterization. Mutants were constructed for all genes in all five species. Each mutant was used to cochallenge C57BL/6 mice via tail vein injection along with each respective wild-type strain to determine competitive indices for each fitness gene. Five fitness factor genes, when mutated, attenuated mutants in four or five species in the spleen and liver (tatC, ruvA, gmhB, wzxE, arcA). Five additional fitness factor genes or operons were validated as outcompeted by wild-type in three, four, or five bacterial species in the spleen (xerC, prc, apaGH, atpG, aroC). Overall, 17 of 18 fitness factor mutants were attenuated in at least one species in the spleen or liver. Together, these findings allow for the development of a model of bacteremia pathogenesis that may include future targets of therapy against bloodstream infections. Author summary: Frequent cases of bacteremia plague our ICUs, bone marrow transplant units, and inpatient facilities. Nearly half of these infections are caused by Gram-negative bacteria. The Enterobacterales order including E. coli, K. pneumoniae, S. marcescens, C. freundii, and E. hormaechei are leading causes of bacteremia. An alarming proportion of these are due to antibiotic-resistant isolates, which are four times more likely to kill than antibiotic-susceptible isolates. Clearly, we need new therapeutic targets to treat cases of bacteremia and sepsis. Previously, it has been unclear what genes contribute to their ability to survive in this hostile host environment. We have previously undertaken unbiased genetic screens to identify genes shared by all five bacterial genera that are required for maintaining bacterial burden in the blood and blood-filtering organs. These include genes that encode proteins that maintain proton motive force, resist antimicrobial peptides and complement, mediate genome maintenance, transport key metabolites and proteins, avoid oxidative stress, acquire iron, and regulate key pathways. Mutants, constructed in these shared genes in the five species, were validated for a high proportion of genes as critical for infection in the mouse model of bacteremia. [ABSTRACT FROM AUTHOR]

Global sorghum production has been significantly reduced due to the occurrence of sorghum root rot caused by the fungus Fusarium graminearum. The utilization of biocontrol microorganisms has emerged as an effective strategy. However, the underlying mechanisms remain unclear. Therefore, the aim of this study was to investigate the effectiveness of biocontrol bacteria in inducing sorghum resistance against sorghum root rot and explore the potential induced resistance mechanisms through metabolomics analysis. The results revealed that the biocontrol bacteria Lnkb100, identified as Serratia marcescens (GenBank: PP152264), significantly enhanced the resistance of sorghum against sorghum root rot and promoted its growth, leading to increased seed weight. Targeted metabolomics analysis demonstrated that the highest concentration of the hormone IAA (indole-3-acetic acid) was detected in the metabolites of Lnkb100. Treatment with IAA enhanced the activity of disease-related enzymes such as SOD, CAT, POD and PPO in sorghum, thereby improving its resistance against sorghum root rot. Further untargeted metabolomic analysis revealed that IAA treatment resulted in higher concentrations of metabolites involved in the resistance against F. graminearum, such as geniposidic acid, 5-L-Glutamyl-taurine, formononetin 7-O-glucoside-6″-O-malonate, as well as higher concentrations of the defense-related molecules volicitin and JA. Additionally, "secondary bile acid biosynthesis" and "glycerophospholipid metabolism" pathways were found to play significant roles in the defense response of sorghum against fungal infection. These findings provide a reliable theoretical basis for utilizing biocontrol microorganisms to control sorghum root rot. [ABSTRACT FROM AUTHOR]

Overnutrition with dietary sugar can worsen infection outcomes in diverse organisms including insects and humans, through generally unknown mechanisms. In the present study, we show that adult Drosophila melanogaster fed high-sugar diets became more susceptible to infection by the Gram-negative bacteria Providencia rettgeri and Serratia marcescens. We found that P. rettgeri and S. marcescens proliferate more rapidly in D. melanogaster fed a high-sugar diet, resulting in increased probability of host death. D. melanogaster become hyperglycemic on the high-sugar diet, and we find evidence that the extra carbon availability may promote S. marcescens growth within the host. However, we found no evidence that increased carbon availability directly supports greater P. rettgeri growth. D. melanogaster on both diets fully induce transcription of antimicrobial peptide (AMP) genes in response to infection, but D. melanogaster provided with high-sugar diets show reduced production of AMP protein. Thus, overnutrition with dietary sugar may impair host immunity at the level of AMP translation. Our results demonstrate that dietary sugar can shape infection dynamics by impacting both host and pathogen, depending on the nutritional requirements of the pathogen and by altering the physiological capacity of the host to sustain an immune response. Author summary: Diet has a critical impact on the quality of immune defense and high-sugar diets increase susceptibility to bacterial infection in many animals. Yet it is unknown which aspects of host and pathogen physiology are impacted by diet to influence infection dynamics. Here we show that high-sugar diets increase susceptibility to some bacterial infections in Drosophila. We find that feeding on high-sugar diet impairs the host immune response by reducing the level of antimicrobial peptides produced. The expression of genes encoding these peptides is not affected, so we infer that protein translation is impaired. We further show that flies on high-sugar diets are hyperglycemic, and that some pathogens may use the excess sugar in the host to promote growth during the infection. Thus, our study demonstrates that dietary impacts on infection outcome arise through physiological effects on both the host and pathogen. [ABSTRACT FROM AUTHOR]

Background: The western flower thrips (WFT), Frankliniella occidentalis Pergande (Thysanoptera: Thripidae), is an important polyphagous pest in both greenhouses and fields. Due to its wide range of host plants and short life cycle, the pest causes overwhelming damage and has led to the destruction of many crops. The combined use of entomopathogenic microorganisms could be an important option to overcome the difficulties in controlling WFT. The virulence of thirty local entomopathogen isolates was tested on WFT, and possibilities of combined application for WFT control were investigated. Results: All isolates were virulent for both the second larval stage and the adult stage of WFT. Serratia marcescens Se9 was the most virulent bacterial isolate with a mortality of 54 and 69.6% against the second larval and the adult stages of WFT, respectively. The LC50 values of the Se9 isolate were determined to be 4 × 106 cfu/ml for the second larval stage and 6.3 × 106 cfu/ml for the adult stage. Among the fungal isolates, Metarhizium flavoviride As18 showed a mortality rate of 92.1 and 74.5% against the second larval and the adult stages of WFT, respectively. The LC50 value was determined to be 1.6 × 104 and 7.1 × 104 conidia/ml for the second larval and adult stages of WFT, respectively. The combined application of S. marcescens Se9 and M. flavoviride As18 at different concentrations generally performed better than single treatments, indicating an additive or synergistic interaction. While the single treatment with S. marcescens and M. flavoviride caused a mortality of 20.4 and 49.5%, respectively, the combined application (S. marcescens LC25; M. flavoviride 100 × LC25) resulted in a mortality of 95.7% of the second larval stage. Similarly, the combined application caused 96% mortality in the adult stage, while the single treatments with S. marcescens and M. flavoviride caused 11.3 and 61.3% mortality, respectively. Conclusion: The study showed that the combined application of S. marcescens (LC25) and M. flavoviride (LC25 × 100) resulted in synergism against both second larval and adult stages of WFT. This is the first study to show that the combination of S. marcescens and M. flavoviride had synergistic potential to suppress the WFT population. In future studies, these microorganisms should be formulated together as biopesticides and tested under greenhouse or field conditions. [ABSTRACT FROM AUTHOR]

Background People with cystic fibrosis (pwCF) are particularly susceptible to respiratory infections, including those caused by multidrug-resistant (MDR) pathogens. Ceftolozane/tazobactam (C/T) is an antibacterial agent combination active against MDR gram-negative bacteria that has shown promising results in isolates from pwCF. This subanalysis is the first extensive observation of real-world C/T use in pwCF. Methods The multicenter observational CONDUCT study included consecutive patients, some with cystic fibrosis, who received ≥1 dose of C/T at 28 centers throughout France. Patients were treated according to hospital standards and followed up until the end of C/T treatment (EOT). Results Among 260 patients who had received ≥1 dose of C/T, 63 were pwCF, including 12 with previous lung transplant. The median age was 34 years and 55.6% of patients were female. Pseudomonas aeruginosa was the most frequently isolated pathogen (n = 40/41 [97.6%]). Most tested P aeruginosa strains (n = 65/73 [91.5%]) and all other isolated strains (Escherichia coli , Citrobacter koseri , Proteus mirabilis , and Serratia marcescens) were susceptible to C/T. Most patients completed the treatment duration, including those with historical β-lactam hypersensitivity. Reasons for stopping treatment were planned EOT and improvement in condition; overall, 88.9% of patients (n = 56/63) experienced improvement in condition. No new safety signals were identified. Mean forced expiratory volume in 1 second improved from 1.33 L to 1.47 L before and after C/T treatment, respectively (n = 52; P =.057). Conclusions C/T treatment was well tolerated and effective in pwCF, including those with previous β-lactam hypersensitivity. [ABSTRACT FROM AUTHOR]

Aims This study aimed to investigate the presence of beta-lactams resistance genes and the clonal relationship of clinical isolates of Enterobacterales obtained from patients with and without COVID-19, in a hospital in northeastern Brazil. Methods and results The study analyzed 45 carbapenem-resistant clinical isolates using enterobacterial repetitive intergenic consensus (ERIC-PCR), PCR, and amplicon sequencing to detect resistance genes (bla KPC, bla GES, bla NDM, bla VIM, and bla IMP). The main species were Klebsiella pneumoniae, Serratia marcescens , and Proteus mirabilis. Detected genes included bla NDM (46.66%), bla KPC (35.55%), and both (17.79%). ERIC-PCR showed multiclonal dissemination and high genetic variability. The main resistance gene was bla NDM, including bla NDM-5 and bla NDM-7. Conclusions The presence of Enterobacterales carrying bla KPC and bla NDM in this study, particularly K. pneumoniae , in infections and colonizations of patients with COVID-19 and non-COVID-19, highlights genetic variability and resistance to carbapenems observed in multiple species of this order. [ABSTRACT FROM AUTHOR]

Opportunistic pathogens are environmental microbes that are generally harmless and only occasionally cause disease. Unlike obligate pathogens, the growth and survival of opportunistic pathogens do not rely on host infection or transmission. Their versatile lifestyles make it challenging to decipher how and why virulence has evolved in opportunistic pathogens. The coincidental evolution hypothesis postulates that virulence results from exaptation or pleiotropy, i.e. traits evolved for adaptation to living in one environment that have a different function in another. In particular, adaptation to avoid or survive protist predation has been suggested to contribute to the evolution of bacterial virulence (the training ground hypothesis). Here, we used experimental evolution to determine how the selective pressure imposed by a protist predator impacts the virulence and fitness of a ubiquitous environmental opportunistic bacterial pathogen that has acquired multidrug resistance: Serratia marcescens. To this aim, we evolved S. marcescens in the presence or absence of generalist protist predator, Tetrahymena thermophila. After 60 d of evolution, we evaluated genotypic and phenotypic changes by comparing evolved S. marcescens with the ancestral strain. Whole-genome shotgun sequencing of the entire evolved populations and individual isolates revealed numerous cases of parallel evolution, many more than statistically expected by chance, in genes associated with virulence. Our phenotypic assays suggested that evolution in the presence of a predator maintained virulence, whereas evolution in the absence of a predator resulted in attenuated virulence. We also found a significant correlation between virulence, biofilm formation, growth, and grazing resistance. Overall, our results provide evidence that bacterial virulence and virulence-related traits are maintained by selective pressures imposed by protist predation. [ABSTRACT FROM AUTHOR]

The negative environmental and social impacts of food waste accumulation can be mitigated by utilizing bio-refineries' approach where food waste is revalorized into high-value products, such as prodigiosin (PG), using microbial bioprocesses. The diverse biological activities of PG position it as a promising compound, but its high production cost and promiscuous bioactivity hinder its wide application. Metal ions can modulate the electronic properties of organic molecules, leading to novel mechanisms of action and increased target potency, while metal complex formation can improve the stability, solubility and bioavailability of the parent compound. The objectives of this study were optimizing PG production through bacterial fermentation using food waste, allowing good quantities of the pure natural product for further synthesizing and evaluating copper(II) and zinc(II) complexes with it. Their antimicrobial and anticancer activities were assessed, and their binding affinity toward biologically important molecules, bovine serum albumin (BSA) and DNA was investigated by fluorescence emission spectroscopy and molecular docking. The yield of 83.1 mg/L of pure PG was obtained when processed meat waste at 18 g/L was utilized as the sole fermentation substrate. The obtained complexes CuPG and ZnPG showed high binding affinity towards target site III of BSA, and molecular docking simulations highlighted the affinity of the compounds for DNA minor grooves. [ABSTRACT FROM AUTHOR]

Serratia marcescens is known to cause outbreaks in neonatal intensive care units (NICUs). Traditionally epidemiological data, antimicrobial resistance patterns and epidemiological typing have been used to guide infection prevention methods. Whole-genome sequencing (WGS) applications such as core-genome multi-locus sequence typing (cgMLST) applied during an outbreak would potentially yield more information. To use cgMLST to acquire detailed information on the source and spread of bacteria, enabling more efficient control measures during an S. marcescens outbreak at a NICU. Neonates admitted to the NICU of the Leiden University Medical Center (LUMC) during an outbreak between September 2023 and January 2024, with S. marcescens being cultured, were included. Environmental samples were taken to search for a common source, antibiotic susceptibility testing was performed, and antimicrobial resistance genes were analysed. S. marcescens strains from 17 of the 20 positive patients were available for molecular typing. The cgMLST scheme revealed five different complex types consisting of four separate clusters. Multiple clusters made an unidentified persistent environmental source as cause of the outbreak less likely, leading to a quick downscaling of infection prevention measures. Differences were shown in aminoglycoside resistance patterns of isolates within the same complex types and patients. The use of ad-hoc cgMLST provided timely data for rational decision-making during an S. marcescens outbreak at the NICU. Antibiotic phenotyping alone was found not to be suitable for studying clonal spread during this outbreak with S. marcescens. [ABSTRACT FROM AUTHOR]

Antimicrobial resistance (AMR) has emerged as a significant threat to public health, particularly in infections caused by critically important Gram-negative bacteria. The development of novel antibiotics has its limitations, and therefore it is crucial to explore alternative strategies to effectively combat infections with resistant pathogens. In this context, the present study investigated the antibacterial potency of 560 compounds against the multidrug-resistant (MDR) strains of Klebsiella pneumoniae and Serratia marcescens. The evaluated compounds were selected from the Pandemic Response Box (PRB) and COVID Box (CB) and subjected to assays to determine the inhibitory concentration (IC), minimum bactericidal concentration (MBC), and biofilm formation. Further, the effects of these compounds on membrane integrity were assessed through protein quantification. Several of the evaluated compounds, including fusidic acid, MMV1580853, and MMV1634399, exhibited a significant reduction in biofilm formation and growth in K. pneumoniae. Trimethoprim exhibited potential against S. marcescens. The IC values of the compounds indicated significant microbial growth inhibition at various concentrations. These findings underscore the potency of the existing antibiotics and novel compounds in combating the MDR strains of bacteria. The importance of reconsidering the known antibiotics and utilizing drug repositioning strategies to address the increasing risk of AMR is highlighted. [ABSTRACT FROM AUTHOR]

Serratia marcescens is an opportunistic human pathogen that produces a vibrant red pigment called prodigiosin. Prodigiosin has implications in virulence of S. marcescens and promising clinical applications. We discovered that addition of the virulent flagellotropic bacteriophage χ (Chi) to a culture of S. marcescens stimulates a greater than fivefold overproduction of prodigiosin. Active phage infection is required for the effect, as a χ-resistant strain lacking flagella does not respond to phage presence. Via a reporter fusion assay, we have determined that the addition of a χ-induced S. marcescens cell lysate to an uninfected culture causes a threefold increase in transcription of the pig operon, containing genes essential for pigment biosynthesis. Replacement of the pig promoter with a constitutive promoter abolished the pigmentation increase, indicating that regulatory elements present in the pig promoter likely mediate the phenomenon. We hypothesize that S. marcescens detects the threat of phage-mediated cell death and reacts by producing prodigiosin as a stress response. Our findings are of clinical significance for two main reasons: (i) elucidating complex phage-host interactions is crucial for development of therapeutic phage treatments, and (ii) overproduction of prodigiosin in response to phage could be exploited for its biosynthesis and use as a pharmaceutical. [ABSTRACT FROM AUTHOR]

Common bean (Phaseolus vulgaris L.) is an essential food staple and source of income for small-holder farmers across Africa. However, yields are greatly threatened by fungal diseases like root rot induced by Rhizoctonia solani. This study aimed to evaluate an integrated approach utilizing vermicompost tea (VCT) and antagonistic microbes for effective and sustainable management of R. solani root rot in common beans. Fourteen fungal strains were first isolated from infected common bean plants collected across three Egyptian governorates, with R. solani being the most virulent isolate with 50% dominance. Subsequently, the antagonistic potential of vermicompost tea (VCT), Serratia sp., and Trichoderma sp. was assessed against this destructive pathogen. Combinations of 10% VCT and the biocontrol agent isolates displayed potent inhibition of R. solani growth in vitro, prompting in planta testing. Under greenhouse conditions, integrated applications of 5 or 10% VCT with Serratia marcescens, Trichoderma harzianum, or effective microorganisms (EM1) afforded up to 95% protection against pre- and post-emergence damping-off induced by R. solani in common bean cv. Giza 6. Similarly, under field conditions, combining VCT with EM1 (VCT + EM1) or Trichoderma harzianum (VCT + Trichoderma harzianum) substantially suppressed disease severity by 65.6% and 64.34%, respectively, relative to untreated plants. These treatments also elicited defense enzyme activity and distinctly improved growth parameters including 136.68% and 132.49% increases in pod weight per plant over control plants. GC–MS profiling of Trichoderma harzianum, Serratia marcescens, and vermicompost tea (VCT) extracts revealed unique compounds dominated by cyclic pregnane, fatty acid methyl esters, linoleic acid derivatives, and free fatty acids like oleic, palmitic, and stearic acids with confirmed biocontrol and plant growth-promoting activities. The results verify VCT-mediated delivery of synergistic microbial consortia as a sustainable platform for integrated management of debilitating soil-borne diseases, enhancing productivity and incomes for smallholder bean farmers through regeneration of soil health. Further large-scale validation can pave the adoption of this climate-resilient approach for securing food and nutrition security. [ABSTRACT FROM AUTHOR]

In this study, for the first time, we isolated a naringinase-producing strain from the Citrus aurantium L. var. amara Engl flower soil and identified it as Serratia marcescens C10. In order to improve naringinase activity for its industrial application, single-factor experiments were carried out to obtain the factors that greatly affect naringinase activity, and based on three factors and three levels of Box-Behnken Designs (BBD), response surface methodology (RSM) was used to optimize the culture conditions consisting of naringin concentration, inoculation size and fermentation time. Results showed that naringin concentration and fermentation time had a highly significant influence and significant influence on naringinase activity, respectively. Additionally, inoculation size and fermentation time had an interaction with naringinase activity. The optimized conditions were a naringin concentration of 0.09 mg/mL, an inoculation size of 5.5%, and a fermentation time of 60 h. Under optimal culture conditions, the experiment naringinase activity was 30.81 U/mL, which was close to the predicted theoretical value of 31.23 U/mL. The optimized naringinase was used to remove naringin in grapefruit juice, and the removal rate was 88.85% under optimal reaction conditions. [ABSTRACT FROM AUTHOR]

Respiratory pathogens, commonly colonizing nasopharynx, are among the leading causes of death due to antimicrobial resistance. Yet, antibiotic resistance determinants within nasopharyngeal microbial communities remain poorly understood. In this prospective cohort study, we investigate the nasopharynx resistome development in preterm infants, assess early antibiotic impact on its trajectory, and explore its association with clinical covariates using shotgun metagenomics. Our findings reveal widespread nasopharyngeal carriage of antibiotic resistance genes (ARGs) with resistomes undergoing transient changes, including increased ARG diversity, abundance, and composition alterations due to early antibiotic exposure. ARGs associated with the critical nosocomial pathogen Serratia marcescens persist up to 8–10 months of age, representing a long-lasting hospitalization signature. The nasopharyngeal resistome strongly correlates with microbiome composition, with inter-individual differences and postnatal age explaining most of the variation. Our report on the collateral effects of antibiotics and prolonged hospitalization underscores the urgency of further studies focused on this relatively unexplored reservoir of pathogens and ARGs. Here, the authors use metagenomics to study the resistome development in the nasopharynx of preterm infants during early life, uncovering a dynamic environment affected by early-life antibiotics and showing long-lasting signature of hospitalization. [ABSTRACT FROM AUTHOR]

H. pylori infection is gaining increasing attention, but detailed investigations into its impact on gastric microbiota remain limited. We collected gastric mucosa samples from 47 individuals divided into three groups: 1. Group HP: patients with initial positive H. pylori infection (25 cases); 2. Group ck: H. pylori-negative patients (14 cases); 3. Group DiffHP: patients with refractory H. pylori infection (8 cases). The samples were analyzed using 16S rDNA sequencing and functional prediction with PICRUSt. Group HP showed differences in flora distribution and function compared to Group ck, while Group DiffHP overlapped with Group HP. The abundances of Aeromonas piscicola, Shewanella algae, Vibrio plantisponsor, Aeromonas caviae, Serratia marcescens, Vibrio parahaemolyticus, Microbacterium lacticum, and Prevotella nigrescens were significantly reduced in both Group DiffHP and Group HP compared to Group ck. Vibrio shilonii was reduced only in Group DiffHP compared to Group ck, while Clostridium perfringens and Paracoccus marinus were increased only in Group DiffHP. LEfSe analysis revealed that Clostridium perfringens and Paracoccus marinus were enriched, whereas Vibrio shilonii was reduced in Group DiffHP compared to Group ck at the species level. In individuals with refractory H. pylori infection, the gastric microbiota exhibited enrichment in various human diseases, organic systems, and metabolic pathways (amino acid metabolism, carbohydrate metabolism, transcription, replication and repair, cell cycle pathways, and apoptosis). Patients with multiple failed H. pylori eradication exhibited significant changes in the gastric microbiota. An increase in Clostridium perfringens and Paracoccus marinus and a decrease in Vibrio shilonii appears to be characteristic of refractory H. pylori infection. [ABSTRACT FROM AUTHOR]

Biofilms play a decisive role in the infectious process and the development of antibiotic resistance. The establishment of bacterial biofilms is regulated by a signal-mediated cell–cell communication process called "quorum sensing" (QS). The identification of quorum sensing inhibitors (QSI) to mitigate the QS process may facilitate the development of novel treatment strategies for biofilm-based infections. In this study, the traditional medicinal plant Ocimum sanctum was screened for QS inhibitory potential. Sub-MICs of the extract significantly affected the secretion of EPS in Gram-negative human pathogens such as Escherichia coli, Pseudomonas aeruginosa PAO1, Proteus mirabilis, and Serratia marcescens, as well as aquaculture pathogens Vibrio harveyi, V. parahaemolyticus, and V. vulnificus, which render the bacteria more sensitive, leading to a loss of bacterial biomass from the substratum. The observed inhibitory activity of the O. sanctum extract might be attributed to the presence of eugenol, as evidenced through ultraviolet (UV)-visible, gas chromatography-mass spectroscopy (GC–MS), Fourier transformer infrared (FTIR) spectroscopy analyses, and computational studies. Additionally, the QSI potential of eugenol was corroborated through in vitro studies using the marker strain Chromobacterium violaceum. [ABSTRACT FROM AUTHOR]

The qualified presumption of safety (QPS) process was developed to provide a safety assessment approach for microorganisms intended for use in food or feed chains. In the period covered by this statement, no new information was found that would change the status of previously recommended QPS TUs. The TUs in the QPS list were updated based on a verification, against their respective authoritative databases, of the correctness of the names and completeness of synonyms. A new procedure has been established to ensure the TUs are kept up to date in relation to recent taxonomical insights. Of 81 microorganisms notified to EFSA between October 2023 and March 2024 (45 as feed additives, 25 as food enzymes or additives, 11 as novel foods), 75 were not evaluated because: 15 were filamentous fungi, 1 was Enterococcus faecium, 10 were Escherichia coli, 1 was a Streptomyces (all excluded from the QPS evaluation) and 46 were TUs that already have a QPS status. Two of the other eight notifications were already evaluated for a possible QPS status in the previous Panel Statement: Heyndrickxia faecalis (previously Weizmannia faecalis) and Serratia marcescens. One was notified at genus level so could not be assessed for QPS status. The other five notifications belonging to five TUs were assessed for possible QPS status. Akkermansia muciniphila and Actinomadura roseirufa were still not recommended for QPS status due to safety concerns. Rhizobium radiobacter can be recommended for QPS status with the qualification for production purposes. Microbacterium arborescens and Burkholderia stagnalis cannot be included in the QPS list due to a lack of body of knowledge for its use in the food and feed chain and for B. stagnalis also due to safety concerns. A. roseirufa and B. stagnalis have been excluded from further QPS assessment. [ABSTRACT FROM AUTHOR]

Edible seaweed - Caulerpa lentillifera is being cultivated along the coast of Khanh Hoa province, Vietnam, and makes a relatively large contribution to the economic development of this region. Bacterial strains originating from marine sources such as those associated with seaweed and hard coral were screened for properties of promote plant growth with the capacity of indole-3-acetic acid (IAA) - a phytohormone belonging to auxin group, the phosphate solubilization ability and antibacterial activity of IAA-producing strains were also performed in this study. Robust strains were identified by morphological methods with biochemical tests and analysis of 16s RNA sequences. Isolate RN06 produced high amounts of IAA, utilized inorganic phosphate, and inhibited Bacillus subtilis ATCC6633, Escherichia coli 0157, and Serratia marcescens PDL100. The IAA producer HRA5 isolated from hard coral demonstrated the ability to solubilize phosphate and exhibited antibacterial activity against B. subtilis. Morphological analysis and 16sRNA sequencing showed that isolate RN06 was the closest strain to Bacillus amyloliquefaciens and HRA5 was linked to Pseudomonas sp. This is the first report of isolated bacteria from seaweed and corals from the Vietnamese sea served as potential strains for further research of the application of biological inoculants specifically for seaweed farming. [ABSTRACT FROM AUTHOR]

BACKGROUND: Psychrophilic bacteria can survive in a unique living environment. OBJECTIVE: To explore the mechanism of low temperature adaptation and the physiological function of thermophilic metabolic genes. METHOD: Serratia marcescens strain F13 stored in microbial laboratory was cultured at 5 ∘ C, 10 ∘ C and 25 ∘ C respectively, and the obtained strains were sequenced by high-throughput transcriptome. Serratia marcescens strain CAV1761 was used as the reference strain. The data produced by transcriptome sequencing were statistically analyzed by biostatistics software such as soapnuke, soap and edger. The differentially expressed genes were found based on the gene expression, and analyzed by Gene Ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. RESULTS: The results showed that there were 718 differential genes in F13-10 vs F13-5 comparison group, 1614 differential genes in F13-25 vs F13-5 comparison group and 1636 differential genes in F13-25 vs F13-10 comparison group. GO function enrichment analysis showed that the GO term mainly enriched by different genes in the three comparison groups was mostly related to the migration and transport of cellular or subcellular components, cell localization and transmembrane transporter activity, as well as cilia or flagella dependent cell movement. In the enrichment analysis of KEGG pathway, the three comparison groups all enriched the largest number of differential genes in the branch pathway of KEGG metabolism, followed by the branch pathway of environmental information processing. CONCLUSION: In F13-10 vs F13-5, the differential genes were mainly concentrated in 20 pathways such as ATP-binding cassette transport (ABC) transporters, thiamine metabolism and flagella assembly; In F13-25 vs F13-5, the differential genes are mainly concentrated in 20 pathways, such as (ABC) transporters, arginine and proline metabolism, two-component system and so on; In F13-25 vs F13-10, the differential genes are mainly concentrated in 20 pathways such as various types of glycan synthesis, two-component system and arginine metabolism. [ABSTRACT FROM AUTHOR]

This study aimed to assess the suitability of fermented food interventions to replenish damaged gut microbiota. Metagenomic assessment of published sequencing data found that fermented food interventions led to a significant increase in the gut antibiotic resistome in healthy human subjects. Antibiotic resistome and viable antibiotic-resistant (AR) bacteria were further highly prevalent in retail kimchi and artisan cheeses by metagenomic and culture analyses. Representative AR pathogens of importance in nosocomial infections, such as Klebsiella pneumoniae, Serratia marcescens, and vancomycin-resistant Enterococcus (VRE), as well as commensals and lactic acid bacteria, were characterized; some exhibited an extremely high minimum inhibitory concentration (MIC) against antibiotics of clinical significance. Exposing fermented food microbiota to representative antibiotics further led to a boost of the corresponding antibiotic and multidrug-resistance gene pools, as well as disturbed microbiota, including the rise of previously undetectable pathogens. These results revealed an underestimated public health risk associated with fermented food intervention at the current stage, particularly for susceptible populations with compromised gut integrity and immune functions seeking gut microbiota rescue. The findings call for productive intervention of foodborne AR via technology innovation and strategic movements to mitigate unnecessary, massive damages to the host gut microbiota due to orally administered or biliary excreted antibiotics. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to discover safe antibacterial and antibiofilm agents from natural sources to control resistant bacteria. Methods: C. gileadensis leaves and stems were collected, identified, and extracted using different organic solvents, methanol, ethyl acetate, chloroform, and hot water. The tested bacteria were multidrug-resistant Escherichia coli, Acinetobacter baumannii, Listeria monocytogenes, Serratia marcescens, Klebsiella pneumonia, Staphylococcus aureus, Pseudomonas aeruginosa. Crystal violet method was used to detect biofilm formation while the phenol-sulphonic acid method to measure exopolysaccharide contents, which are an effective factor in biofilm formation. Results: No significant differences were noted in the biological activities between leave and stem. Ethyl acetate and chloroform extracts showed lower activities. Still, hot water extract showed the weakest activities.There is a synergistic effect between the Commiphora extract and some antibiotics, especially Amoxicillin, Polymixin B, and Tetracycline. The highest inhibition of biofilm was recorded against K. pneumonia which had the highest EPS content (0.29 ± 0.04 μg/mg of cells), decreased after treatment with plant extract by 39%. Cytotoxicity studies using Artimia salina as a test organism were conducted for the methanolic extracts, which showed antitumor activity against two cell lines, MCF-7 (breast cancer) and HepG2 (hepatocellular carcinoma). Commiphora extract showed antioxidant activity using two different protocols. Conclusion: The methanolic extract of Commiphora singly or in combination with antibiotics inhibit many pathogenic bacteria that form biofilm and recorded antitumor and antioxidant activities. [ABSTRACT FROM AUTHOR]

Phospholipase A1 (PLA1) is a kind of specific phospholipid hydrolase widely used in food, medical, textile. However, limitations in its expression and enzymatic activity have prompted the investigation of the phospholipase-assisting protein PlaS. In this study, we elucidate the role of PlaS in enhancing the expression and activity of PlaA1 through N-terminal truncation. Our research demonstrates that truncating the N-terminal region of PlaS effectively overcomes its inhibitory effect on host cells, resulting in improved cell growth and increased protein solubility of the protein. The yeast two-hybrid assay confirms the interaction between PlaA1 and N-terminal truncated PlaS (∆N27 PlaS), highlighting their binding capabilities. Furthermore, in vitro studies using Biacore analysis reveal a concentration-dependent and specific binding between PlaA1 and ∆N27 PlaS, exhibiting high affinity. Molecular docking analysis provides insights into the hydrogen bond interactions between ∆N27 PlaS and PlaA1, identifying key amino acid residues crucial for their binding. Finally, the enzyme activity of PLA1 was boost to 8.4 U/mL by orthogonal test. Study significantly contributes to the understanding of the interaction mechanism between PlaS and PlaA1, offering potential strategies for enhancing PlaA1 activity through protein engineering approaches. [ABSTRACT FROM AUTHOR]

Prodigiosin (PG) is a red tripyrrole pigment from the prodiginine family that has attracted widespread attention due to its excellent biological activities, including anticancer, antibacterial and anti-algal activities. The synthesis and production of PG is of particular significance, as it has the potential to be utilized in a number of applications, including those pertaining to clinical drug development, food safety, and environmental management. This paper provides a systematic review of recent research on PG, covering aspects like chemical structure, bioactivity, biosynthesis, gene composition and regulation, and optimization of production conditions, with a particular focus on the biosynthesis and regulation of PG in Serratia marcescens. This provides a solid theoretical basis for the drug development and production of PG, and is expected to promote the further development of PG in medicine and other applications. [ABSTRACT FROM AUTHOR]

Preserving boar semen at 5°C instead of the conventional storage temperature of 17°C would enable a reduction of antibiotic use in pig insemination. To protect the chilling-sensitive boar spermatozoa, holding the extended semen at a higher temperature before cooling could be beneficial and facilitate the implementation of the innovative preservation concept in practice, provided that bacterial growth is kept at a low level. The aim of this study was to introduce a holding time (HT) at 17°C before cooling and to examine the effect on sperm quality and bacterial growth compared to the original cooling protocol for antibiotic-free 5°C semen storage. A series of experiments with semen doses from eight boars extended in Androstar® Premium without conventional antibiotics revealed that sperm kinematics and the integrity of sperm plasma membranes and acrosomes were improved with HT between 16 and 24 h followed by delayed cooling with 0.04°C/min when compared to the original protocol for semen preservation at 5°C (p < 0.05). Both a shorter HT of 6 h and a faster cooling rate of 0.07°C/min reduced sperm quality (p < 0.05). The HT for 24 h did not compromise the inhibitory effect on bacterial growth during long-term semen storage at 5°C, not even in semen doses spiked with Serratia marcescens. In conclusion, semen storage at 5°C with the modified cooling protocol improved sperm quality and is antimicrobially efficient. It thus presents a ready-to-use tool for a reduction or replacement of antibiotics in pig insemination. [ABSTRACT FROM AUTHOR]