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Recently, we reported the discovery of a novel endoglucanase of the glycoside hydrolase family 12 (GH12), designated IfCelS12A, from the haloalkaliphilic anaerobic bacterium Iocasia fonsfrigidae strain SP3-1, which was isolated from a hypersaline pond in the Samut Sakhon province of Thailand (ca. 2017). IfCelS12A exhibits high substrate specificity on carboxymethyl cellulose and amorphous cellulose but low substrate specificity on b-1,3;1,4-glucan. Unlike some endoglucanases of the GH12 family, IfCelS12A does not exhibit hydrolytic activity on crystalline cellulose (i.e., Avicel™). High-Pressure Liquid Chromatography (HPLC) and Thin Layer Chromatography (TLC) analyses of products resulting from IfCelS12-mediated hydrolysis indicate mode of action for this enzyme. Notably, IfCelS12A preferentially hydrolyzes cellotetraoses, cellopentaoses, and cellohexaoses with negligible activity on cellobiose or cellotriose. Kinetic analysis with cellopentaose and barely b-D-glucan as cellulosic substrates were conducted. On cellopentaose, IfCelS12A demonstrates a 16-fold increase in activity (K M  = 0.27 mM; k cat  = 0.36 s -1 ; k cat /K M  = 1.34 mM -1 s -1 ) compared to the enzymatic hydrolysis of barley b-D-glucan (K M : 0.04 mM, k cat : 0.51 s -1 , k cat /K M  = 0.08 mM -1 s -1 ). Moreover, IfCelS12A enzymatic efficacy is stable in hypersaline sodium chlorids (NaCl) solutions (up to 10% NaCl). Specifically, IfCel12A retains notable activity after 24 h at 2M NaCl (10% saline solution). IfCelS12A used as a cocktail component with other cellulolytic enzymes and in conjunction with mobile sequestration platform technology offers additional options for deconstruction of ionic liquid-pretreated cellulosic feedstock. KEY POINTS: • IfCelS12A from an anaerobic alkaliphile Iocasia fronsfrigidae shows salt tolerance • IfCelS12A in cocktails with other enzymes efficiently degrades cellulosic biomass • IfCelS12A used with mobile enzyme sequestration platforms enhances hydrolysis., (© 2024. The Author(s).)

The control of digital dermatitis (DD) among cattle is crucial; however, effective and environmentally-sound control measures have yet to be identified. From the monitoring data of DD which were recorded during regular hoof trimmings in a farm in Hokkaido, Japan, we detected a decrease in the DD prevalence in a herd where an anaerobic bacterial fermentation enhancer (ABFE) was distributed. The possible effect of ABFE was analyzed using a retrospective repeated cross-sectional design. The prevalence of DD decreased over time in the ABFE-distributed group. Furthermore, a selected regression model indicated the time-dependent enhancement of the decreasing trend. While potential coincidental factors may influence, this study provides a basis for further research on the preventive effect of ABFE against DD.

Hidradenitis Suppurativa (HS) is a chronic autoinflammatory skin disease with activated keratinocytes, tunnel formation and a complex immune infiltrate in tissue. The HS microbiome is polymicrobial with an abundance of commensal gram-positive facultative (GPs) Staphylococcus species and gram-negative anaerobic (GNA) bacteria like Prevotella, Fusobacterium and Porphyromonas with increasing predominance of GNAs with disease severity. We sought to define the keratinocyte response to bacteria commonly isolated from HS lesions to probe pathogenic relationships between HS and the microbiome. Type strains of Prevotella nigrescens, Prevotella melaninogenica, Prevotella intermedia, Prevotella asaccharolytica, Fusobacterium nucleatum, as well as Staphylococcus aureus and the normal skin commensal Staphylococcus epidermidis were heat-killed and co-incubated with normal human keratinocytes. RNA was collected and analysed using RNAseq and RT-qPCR. The supernatant was collected from cell culture for protein quantification. Transcriptomic profiles between HS clinical samples and stimulated keratinocytes were compared. Co-staining of patient HS frozen sections was used to localize bacteria in lesions. A mouse intradermal injection model was used to investigate early immune recruitment. TLR4 and JAK inhibitors were used to investigate mechanistic avenues of bacterial response inhibition. GNAs, especially F. nucleatum, stimulated vastly higher CXCL8, IL17C, CCL20, IL6, TNF and IL36γ transcription in normal skin keratinocytes than the GPs S. epidermidis and S. aureus. Using RNAseq, we found that F. nucleatum (and Prevotella) strongly induced the IL-17 pathway in keratinocytes and overlapped with transcriptome profiles of HS patient clinical samples. Bacteria were juxtaposed to activated keratinocytes in vivo, and F. nucleatum strongly recruited murine neutrophil and macrophage migration. Both the TLR4 and pan-JAK inhibitors reduced cytokine production. Detailed transcriptomic profiling of healthy skin keratinocytes exposed to GNAs prevalent in HS revealed a potent, extensive inflammatory response vastly stronger than GPs. GNAs stimulated HS-relevant genes, including many genes in the IL-17 response pathway, and were significantly associated with HS tissue transcriptomes. The close association of activated keratinocytes with bacteria in HS lesions and innate infiltration in murine skin cemented GNA pathogenic potential. These novel mechanistic insights could drive future targeted therapies., (© 2024 The Authors. Experimental Dermatology published by John Wiley & Sons Ltd.)

The vast majority of processes in the carbon and nitrogen cycles are driven by microorganisms. The nitrite-dependent anaerobic oxidation of methane (N-DAMO) process links carbon and nitrogen cycles, offering a novel approach for the simultaneous reduction of methane emissions and nitrite pollution. However, there is currently no comprehensive summary of the current status of the N-DAMO process in natural aquatic environments. Therefore, our study aims to fill this knowledge gap by conducting a comprehensive review of the global research trends in N-DAMO processes in various aquatic environments (excluding artificial bioreactors). Our review mainly focused on molecular identification, global study sites, and their interactions with other elemental cycling processes. Furthermore, we performed a data integration analysis to unveil the effects of key environmental factors on the abundance of N-DAMO bacteria and the rate of N-DAMO process. By combining the findings from the literature review and data integration analysis, we proposed future research perspectives on N-DAMO processes in global aquatic environments. Our overarching goal is to advance the understanding of the N-DAMO process and its role in synergistically reducing carbon emissions and removing nitrogen. By doing so, we aim to make a significant contribution to the timely achievement of China's carbon peak and carbon neutrality targets., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Facultatively anaerobic bacterial strains were isolated from samples of a methanogenic reactor and, based on 16S rRNA gene sequences, found to be affiliated with the family Propionibacteriaceae in the phylum Actinomycetota. Four strains with almost-identical 16S rRNA gene sequences were comprehensively characterized. The most closely related species to the strains was Brooklawnia cerclae BL-34 T (96.4 % sequence similarity). Although most of the phenotypic characteristics of the four strains were identical, distinct differences in some cellular and physiological properties were also detected. Cells of the strains were Gram-stain-positive, non-spore-forming, pleomorphic rods. The strains utilized carbohydrates and organic acids. The strains produced acetate, propionate and lactate from glucose, but the molar ratios of the products were variable depending on the strains. The strains grew at 10-40 °C (optimum at 35 °C) and pH 5.3-8.8 (optimum at pH 6.8-7.5.) The major cellular fatty acids of the strains were anteiso-C 15 : 0 , C 15 : 0 and C 15 : 0 dimethylacetal (as a summed feature). The major respiratory quinone was menaquinone MK-9(H 4 ) and the diagnostic diamino acid in the peptidoglycan was meso -diaminopimelic acid. The genome size of the type strain (SH051 T ) was 3.21 Mb and the genome DNA G+C content was 65.7 mol%. Genes responsible for propionate production through the Wood-Werkman pathway were detected in the genome of strain SH051 T . Based on the results of phylogenetic, genomic and phenotypic analyses of the novel strains, the name Brooklawnia propionicigenes sp. nov. is proposed to accommodate the four strains. The type strain of the novel species is SH051 T (=NBRC 116195 T =DSM 116141 T ).

Recovering resources from wastewater to alleviate the energy crisis has become the prevailing trend of technological development. Purple phototrophic bacteria (PPB), a group of fast-growing microbes, have been widely noticed for their potential in producing value-added products from waste streams. However, saline contents in these waste streams, such as food processing wastewater pose a big challenge, which not only restrain the pollutant removal efficiency, but also hinder the growth of functional microbes. To overcome this, a photo anaerobic membrane bioreactor cultivating PPB (PPB-MBR) was constructed and its performance upon long-term salinity stress was investigated. PPB-MBR achieved desirable pollutants removal performance with the average COD and NH 4 + removal efficiency being 87% (±8%, n = 87) and 89% (±10%, n = 87), respectively during long-term exposure to salinity stress of 1-80 g NaCl L -1 . PPB were predominant during the entire operation period of 87 days (60%-80%), obtaining maximum biomass yield of 0.67 g biomass g -1 COD removed and protein productivity of 0.18 g L -1 d -1 at the salinity level of 20 g NaCl L -1 and 60 g NaCl L -1 , respectively. The sum of value-added products in proportion to the biomass reached 58% at maximum at the salinity level of 60 g NaCl L -1 with protein, pigments and trehalose contributing to 44%, 8.7%, and 5%, respectively. Based on economic analysis, the most cost-saving scenario treating food processing wastewater was revealed at salinity level of around 20 g NaCl L -1 . However, more optimization tools are needed to boost the production efficiency so that the profit from value-added products can outweigh the additional cost by excess salinity in the future implication., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Background: A notable improvement in the treatment of necrotizing soft tissue infections (NSTIs) is the development of negative pressure wound therapy (NPWT). Clinicians are still debating whether NPWT is as successful as conventional wet-to-dry dressings at removing bacteria. Recent research has revealed potential oxygen deprivation effects of NPWT in underlying wound tissues, although clinical trials regarding the effects of reduced oxygen on anaerobic bacterial soft tissue infections remain noticeably lacking. Hypothesis: We hypothesized that NPWT-treated patients with NSTIs who were solely infected by anaerobic bacteria would have worse outcomes than those who were infected with other bacterial species . Patients and Methods: Our study included a retrospective examination of the 2008-2022 period of our Acute and Critical Care Surgery database. Patients who had been identified as having necrotizing fasciitis, Fournier gangrene, or gas gangrene and who had their conditions verified by positive wound cultures acquired during the initial debridement and subsequently received NPWT made up the study cohort. Comorbidities, surgical techniques, and clinical results were all covered by the data. Based on their wound infections, patients were divided into two groups: those with exclusively anaerobic NSTIs and those with different bacterial groups (such as polymicrobial and aerobic). Multiple regression, χ 2 analysis, and analysis of variance (ANOVA) were among the analytical methods used. Results: One hundred twelve patients with NSTI who had received NPWT comprised the study cohort. Sixteen of these patients (14.3%) had NSTIs that were exclusively anaerobic, whereas the remaining 96 (85.7%) had NSTIs that were mixed aerobic, facultative, or polymicrobial. Between the two groups, there was no difference in the initial wound size. Patients with anaerobic NSTI who underwent NPWT showed a statistically significant increase in the number of debridements (3 [interquartile range {IQR},1-9] vs. 2 [IQR, 1-4]; p = 0.012) and an increased 100-day re-admission rate (37.5% vs. 12.5%; p = 0.012) when compared with patients with non-anaerobic NSTI. The 100-day re-admission rate increased three-fold in NPWT-treated anaerobic NSTIs, according to a logistic regression analysis (odds ratio [OR], 3.63; 95% confidence interval [CI], 1.06-12.44; p = 0.04). Conclusions: In contrast to patients with other bacterial strains, our data show that patients with NSTI treated with NPWT who only have anaerobic bacterial infections have a larger number of debridements and are much more likely to require re-admission within 100 days. We call for additional prospective studies to be conducted to identify additional risk factors and consider alternate treatment options for individuals with exclusively anaerobic NSTIs in light of these findings.

Acne is a prevalent dermatological disease, with high global incidence, and is a health menace. The current study aimed to isolate and characterize the anaerobic bacteria responsible for the condition. Causes of a total of 70 acne-based bacterium isolates obtained from patients of mild, moderate, and severe acne, 24 were Clostridium innocuum, 21 were Lactobacillus plantarum, 13 were Anaerococcus prevotii, and 12 were Peptoniphilus asaccharolyticus. Nearly 69% of males were suffering, while the rest were females at 31%. The 15-30 years old age group was the most affected. The gold/alginate nanoparticles' nanopreparation (GANPs) produced from chloroauric acid and sodium alginate was an effective treatment against the acne conditions under the experimental conditions. The nanopreparation exhibited significant inhibitory activity against anaerobic bacterial isolates, with a minimum inhibitory concentration of 200 µg/ml for A. prevotii and P. asaccharolyticus, and 400 µg/ml for C. innocuum and L. plantarum. The in vitro efficacy of the GANPs on human blood parameters was also assessed. The concurrent results suggested potential antibacterial activity and hemocompatibility of the product, which has promise to be used as a successful antibacterial agent for acne., (© 2024. The Author(s).)

Anaerobes dominate the microbiota of the gastrointestinal (GI) tract, where a significant portion of small molecules can be degraded or modified. However, the enormous metabolic capacity of gut anaerobes remains largely elusive in contrast to aerobic bacteria, mainly due to the requirement of sophisticated laboratory settings. In this study, we employed an in silico machine learning platform, MoleculeX, to predict the metabolic capacity of a gut anaerobe, Clostridium sporogenes, against small molecules. Experiments revealed that among the top seven candidates predicted as unstable, six indeed exhibited instability in C. sporogenes culture. We further identified several metabolites resulting from the supplementation of everolimus in the bacterial culture for the first time. By utilizing bioinformatics and in vitro biochemical assays, we successfully identified an enzyme encoded in the genome of C. sporogenes responsible for everolimus transformation. Our framework thus can potentially facilitate future understanding of small molecules metabolism in the gut, further improve patient care through personalized medicine, and guide the development of new small molecule drugs and therapeutic approaches., (© 2024 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

The Sargassum phenomenon is currently affecting the Caribbean in several ways; one of them is the increase of greenhouse gases due to the decomposition process of this macroalgae; these processes also produce large amounts of pollutant leachates, in which several microbial communities are involved. To understand these processes, we conducted a 150-day study on the Sargassum spp environmental degradation under outdoor conditions, during which leachates were collected at 0, 30, 90, and 150 days. Subsequently, a metagenomic study of the microorganisms found in the leachates was carried out, in which changes in the microbial community were observed over time. The results showed that anaerobic bacterial genera such as Thermofilum and Methanopyrus were predominant at the beginning of this study (0 and 30 days), degrading sugars of sulfur polymers such as fucoidan, but throughout the experiment, the microbial communities were changed also, with the genera Fischerella and Dolichospermum being the most predominant at days 90 and 150, respectively. A principal component analysis (PCA) indicated, with 94% variance, that genera were positively correlated at 30 and 90 days, but not with initial populations, indicating changes in community structure due to sargassum degradation were present. Finally, at 150 days, the leachate volume decreased by almost 50% and there was a higher abundance of the genera Desulfobacter and Dolichospemum. This is the first work carried out to understand the degradation of Sargassum spp, which will serve, together with other works, to understand and provide a solution to this serious environmental problem in the Caribbean., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Anammox bacteria are being increasingly investigated as part of an emerging nitrogen removal technology. However, due to the difficulty in culturing, current understanding of their behavior is limited. In this study, anaerobic microfluidic chips were used to study anammox bacteria, showing great advantages over reactors. On-chip fluorescence in situ hybridization (FISH) showed the relative abundance of free form anammox bacteria increased by 56.1 % after one week's culture, an increase that is three times higher than that of bioreactor (17.1 %). For granular form cultures, the nitrogen removal load reached 2.34 ∼ 2.51 kg-N/(m 3 ·d), which was also substantially higher than the bioreactor (∼1.22 kg-N/(m 3 ·d)). Furthermore, studying the kinetics of nitrite inhibition of granular sludge with different particle sizes (100-900 μm) showed that the maximum ammonia load and the nitrite semi-saturation coefficient noticeably decreased for smaller particle sizes. These results illustrate the usefulness of the microfluidic method for in-depth understanding anammox process and its implementation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

There is growing evidence that altered microbiota abundance of a range of specific anaerobic bacteria are associated with cancer, including Peptoniphilus spp., Porphyromonas spp., Fusobacterium spp., Fenollaria spp., Prevotella spp., Sneathia spp ., Veillonella spp . and Anaerococcus spp. linked to multiple cancer types. In this review we explore these pathogenic associations. The mechanisms by which bacteria are known or predicted to interact with human cells are reviewed and we present an overview of the interlinked mechanisms and hypotheses of how multiple intracellular anaerobic bacterial pathogens may act together to cause host cell and tissue microenvironment changes associated with carcinogenesis and cancer cell invasion. These include combined effects on changes in cell signalling, DNA damage, cellular metabolism and immune evasion. Strategies for early detection and eradication of anaerobic cancer-associated bacterial pathogens that may prevent cancer progression are proposed.

The human gut microbiome is a key contributor to health, and its perturbations are linked to many diseases. Small-molecule xenobiotics such as drugs, chemical pollutants and food additives can alter the microbiota composition and are now recognized as one of the main factors underlying microbiome diversity. Mapping the effects of such compounds on the gut microbiome is challenging because of the complexity of the community, anaerobic growth requirements of individual species and the large number of interactions that need to be quantitatively assessed. High-throughput screening setups offer a promising solution for probing the direct inhibitory effects of hundreds of xenobiotics on tens of anaerobic gut bacteria. When automated, such assays enable the cost-effective investigation of a wide range of compound-microbe combinations. We have developed an experimental setup and protocol that enables testing of up to 5,000 compounds on a target gut species under strict anaerobic conditions within 5 d. In addition, with minor modifications to the protocol, drug effects can be tested on microbial communities either assembled from isolates or obtained from stool samples. Experience in working in an anaerobic chamber, especially in performing delicate work with thick chamber gloves, is required for implementing this protocol. We anticipate that this protocol will accelerate the study of interactions between small molecules and the gut microbiome and provide a deeper understanding of this microbial ecosystem, which is intimately intertwined with human health., (© 2023. Springer Nature Limited.)

Two cocci-shaped, facultatively anaerobic, Gram-positive bacteria isolated from the faeces of a pig were designated as strains YH-aer221 T and YH-aer222. Analysis of the 16S rRNA gene sequences revealed that the isolates were most closely related to Aerococcus suis JCM 18035 T with 96.6 % similarity. The multi-locus sequence tree revealed that the isolates formed a sub-cluster adjacent to A. suis JCM 18035 T . The average nucleotide identity values for the isolates and their most closely related strains were 71.8 and 71.7 %, respectively; and the digital DNA-DNA hybridization values for the isolates and their most closely related strains were 25.6 and 25.5 %, respectively. The main fatty acids were C 18 : 1 ω9 c , C 16 : 0 and C 18 : 0 . The cell wall contained the meso -diaminopimelic acid-based peptidoglycan. The two isolates shared the same metabolic pathways. Isolates YH-aer221 T and YH-aer222 harboured the same CRISPR array with 33 and 46 spacers, respectively. Single-genome vs. metagenome analysis showed that the genomes of the isolates were not found in the available metagenome database. Given their chemotaxonomic, phenotypic and phylogenetic properties, YH-aer221 T (= KCTC 25571 T =JCM 35699 T ) and YH-aer222 (=KCTC 25573=JCM 35700) represent a novel taxon. The name Aerococcus kribbianus sp. nov. is proposed.

Wild strains of Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis were tested in an experimental hyperbaric chamber to determine the possible effect of hyperbaric oxygen on the susceptibility of these strains to the antibiotics ampicillin, ampicillin + sulbactam, cefazolin, cefuroxime, cefoxitin, gentamicin, sulfamethoxazole + trimethoprim, colistin, oxolinic acid, ofloxacin, tetracycline, and aztreonam during their cultivation at 23 °C and 36.5 °C. Ninety-six-well inoculated microplates with tested antibiotics in Mueller-Hinton broth were cultured under standard incubator conditions (normobaric normoxia) for 24 h or in an experimental hyperbaric chamber (HAUX, Germany) for 24 h at 2.8 ATA of 100% oxygen (hyperbaric hyperoxia). The hyperbaric chamber was pressurised with pure oxygen (100%). Both cultures (normoxic and hyperoxic) were carried out at 23 °C and 36.5 °C to study the possible effect of the cultivation temperature. No significant differences were observed between 23 and 36.5 °C cultivation with or without the 2-h lag phase in Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis. Cultivation in a hyperbaric chamber at 23 °C and 36.5 °C with or without a 2-h lag phase did not produce significant changes in the minimum inhibitory concentration (MIC) of Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis. For the tested strains of Pseudomonas aeruginosa, the possible effect of hyperbaric oxygen on their antibiotic sensitivity could not be detected because the growth of these bacteria was completely inhibited by 100% hyperbaric oxygen at 2.8 ATA under all hyperbaric conditions tested at 23 °C and 36.5 °C. Subsequent tests with wild strains of pseudomonads, burkholderias, and stenotrophomonads not only confirmed the fact that these bacteria stop growing under hyperbaric conditions at a pressure of 2.8 ATA of 100% oxygen but also indicated that inhibition of growth of these bacteria under hyperbaric conditions is reversible., (© 2023. The Author(s).)

Hypersaline organic wastewater is characterized as being nitrogen-deficient, and is easily prone to sludge bulking. In this study, the stability of halophilic aerobic granular sludge (HAGS) for the treatment of hypersaline organic wastewater is explored. Along with the decrease of influent ammonium, the bacterial population substantially reduced, whereas the fungal population continuously increased in HAGS. Saccharomycetales in fungi become the dominant sequence (99.78%) in HAGS bulking. Additionally, Halanaerobium (77.47%) remained prevalent in HAGS despite bacterial washout. Halanaerobium, a nitrogen-fixing genus of bacteria, provided nitrogen for ammonium-assimilating fungi. Saccharomycetales encapsulating HAGS reduced the transfer efficiency of dissolved oxygen, thereby creating favorable growth conditions for Halanaerobium. This paper for the first time highlights the mutualistic symbiosis of fungi and bacteria in HAGS treating the hypersaline organic wastewater. The study lays the foundation for the control and recovery of HAGS bulking., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier Ltd.)

The aim of this study was to describe the in vitro activity of delafloxacin against 230 anaerobic isolates and compare it with the activity of other antimicrobials used against infections caused by anaerobic microorganisms. Minimal inhibitory concentrations (MICs) were lower for delafloxacin than for all other antibiotics tested with the exception of piperacillin-tazobactam and meropenem against Gram-positive anaerobic cocci. Only two (0.8 %) isolates of Bacteroides spp. showed a MIC ≥4 μg/mL. With some exceptions, the present results show lower MICs for delafloxacin in comparison to the other antibiotics used against anaerobes., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Butyrate-producing bacteria are a functionally important part of the intestinal tract flora, and the resulting butyric acid is essential for maintaining host intestinal health, regulating the immune system, and influencing energy metabolism. However, butyrate-producing bacteria have not been defined as a coherent phylogenetic group. They are primarily identified using primers for key genes in the butyrate-producing pathway, and their use has been limited to the Bacillota and Bacteroidetes phyla. To overcome this limitation, we developed functional gene primers able to identify butyrate-producing bacteria through the butyrate kinase gene, which encodes the enzyme involved in the final step of the butyrate-producing pathway. Genomes extracted from human and rat feces were used to amplify the target genes through PCR. The obtained sequences were analyzed using BLASTX to construct a developmental tree using the MEGA software. The newly designed butyrate kinase gene primers allowed to recognize a wider diversity of butyrate-producing bacteria than that recognized using currently available primers. Specifically, butyrate-producing bacteria from the Synergistota and Spirochaetota phyla were identified for the first time using these primers. Thus, the developed primers provide a more accurate method for researchers and doctors to identify potential butyrate-producing bacteria and deepen our understanding of butyrate-producing bacterial species., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Importance: Microorganisms inadvertently introduced into the shale reservoir during fracturing face multiple stressors including brine-level salinities and starvation. However, some anaerobic halotolerant bacteria adapt and persist for long periods of time. They produce hydrogen sulfide, which sours the reservoir and corrodes engineering infrastructure. In addition, they form biofilms on rock matrices, which decrease shale permeability and clog fracture networks. These reduce well productivity and increase extraction costs. Under stress, microbes remodel their plasma membrane to optimize its roles in protection and mediating cellular processes such as signaling, transport, and energy metabolism. Hence, by observing changes in the membrane lipidome of model shale bacteria, Halanaerobium congolense WG10, and mixed consortia enriched from produced fluids under varying subsurface conditions and growth modes, we provide insight that advances our knowledge of the fractured shale biosystem. We also offer data-driven recommendations for improving biocontrol efficacy and the efficiency of energy recovery from unconventional formations., Competing Interests: Fabrizio Colosimo is currently employed by New England Biolabs, Ipswich, MA, United States. Jishnu Adhikari is currently employed by Tetra Tech Inc., King of Prussia, PA, United States. The remaining authors declare no conflict of interest.

Actinotignum schaalii (formerly known as Actinobaculum schaalii) is an anaerobic or facultative anaerobic gram-positive bacillus that can be found commensally in the urogenital region. It can be overlooked because it grows slowly and is difficult to identify with classical microbiology laboratory techniques. Colonies become visible after 48-72 hours of incubation on blood agar in anaerobic or CO₂-rich media. While it typically causes urinary tract infection in older individuals, cases of bacteremia, vertebral osteomyelitis, endocarditis and cellulitis have been reported. Fournier's gangrene caused by A.schaalii has been reported very rarely so far. Fournier's gangrene has been defined as necrotizing fasciitis of the external genitalia, perineal and perianal region. Diabetes, immunosuppression, peripheral vascular disease, urethral anomalies, chronic alcoholism and smoking are important predisposing factors. In addition, approximately 25% of the cases have no known or identifiable etiology. The bacteria causing the infection may originate from skin, urogenital or intestinal microbiota. In this case report, a new case of Fournier's gangrene caused by A.schaalii was presented. A 65-year-old male patient admitted to the emergency department with the complaints of pain, swelling, redness in the left testis and also nausea, vomiting and chills that started three days ago. Physical examination revealed increased diameter of the scrotum, intense hyperemia of the skin and foci of necrosis. It was learned that the patient had no known chronic disease other than benign prostatic hyperplasia. The patient reported smoking of 25 packs of cigarettes per year. Routine laboratory tests revealed leukocyte= 32.41 x 109/L, neutrophil= 89.9%, procalcitonin= 1.62 ug/L, CRP= 265.07 mg/L and the patient was operated with the diagnosis of Fournier's gangrene. Gram staining of the abscess specimen obtained during the operation showed gram-positive bacilli both inside and outside the leukocytes. After 24 hours, grampositive bacilli were detected in the Gram staining of thin, transparent/gray colonies grown on 5% sheep blood and chocolate agar. The isolate was identified as A.schaalii by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) VITEK® MS (bioMérieux, France) microbial identification system. VITEK®2 ID ANC (bioMérieux, France) bacterial identification card was also used for comparison but the bacteria could be identified. As a result of the sequence analysis performed for confirmation, it was shown to be 100% homologous with Actinobaculum schaalii (GenBank accession no: FJ711193.1). For susceptibility tests, 5% sheep blood Schaedler agar was used and incubated in anaerobic environment. According to the minimal inhibitory concentration (MIC) results evaluated after 48 hours, penicillin was found to be 0.032 mg/L, clindamycin 0.125 mg/L, ciprofloxacin 0.19 mg/L, ceftazidime 4 mg/L, and amoxicillin 0.19 mg/L. The primary cause that initiated the infection in the case could not be identified, but it was thought that the presence of prostatic hyperplasia and smoking history may have contributed to the occurence or the progress of the disease. It is noteworthy that the ciprofloxacin MIC result was quite low compared to other studies. In addition, this study revealed the value of MALDI-TOF MS based methods in identification. In conclusion, it is thought that a significant proportion of A.schaalii infections may be overlooked due to the difficulty in growth and identification. Increasing the diagnostic power of clinical microbiology laboratories for poorly identified bacteria and renewing the databases of commercial identification systems are important for the early and accurate diagnosis and treatment of serious infections that may occur with such agents.

Renew interest and enthusiasm for anaerobes stem from both technological improvements (culture media, production of an adequate anaerobic atmosphere, identification methods) and greater awareness on the part of clinicians. Anaerobic infections were historically treated empirically, targeting the species known to be involved in each type of infection. Prevotella, fusobacteria, and Gram-positive cocci (GPAC) were considered responsible for infections above the diaphragm whereas for intra-abdominal infections, Bacteroides of the fragilis group (BFG), GPAC and clostridia were predominantly implicated. The antibiotic susceptibility of anaerobes was only taken into consideration by the clinician in the event of treatment failure or when faced with infections by multidrug-resistant bacteria (MDR). The evolution of antibiotic resistance together with clinical failures due to the absence of detection of hetero-resistant clones has resulted in a greater need for accessible antibiotic susceptibility testing (AST) and disc diffusion method. Improved isolation and identification of anaerobes, along with the availability of accessible and robust methods for performing AST, will ensure that treatment, whether empirical or guided by an antibiogram, will lead to better outcomes for anaerobic infections., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The partial nitritation/anammox (PN/A) process has been widely used in wastewater treatment owing to its notable advantages, including a low aeration rate and the non-requirement of an additional carbon source. In practical implementation, nitrite accumulation affects the nitrogen-removal efficiency and the amount of N 2 O released during the PN/A process. By implementing wastewater reflux, the nitrite concentration can be decreased, thereby achieving a balance between the nitrogen-removal efficiency and N 2 O release. This study conducted the CANON process with varying reflux ratios of 0 to 300 % and ~300 mg/L ammonium in the influent. The highest removal efficiency of ammonium and total nitrogen (98.2 ± 0.8 and 77.8 ± 2.3 %, respectively) could be achieved at a reflux ratio of 200 %. Further, a reflux ratio of 200 % led to the lowest N 2 O emission factor (2.21 %), with a 31.74 % reduction in N 2 O emission compared to the process without refluxing. Additionally, the reactor at a reflux ratio of 200 % presented the highest relative abundance of anaerobic ammonium-oxidizing bacteria (30.98 %) and the lowest proportion of ammonium-oxidizing bacteria (9.57 %). This study aimed to elucidate the impact of the reflux ratio on the nitrogen-removal efficiency of the CANON process and to theoretically explain the influence of different reflux ratios on N 2 O release. These findings provide a theoretical framework for enhancing the nitrogen-removal efficiency and mitigating carbon emissions in practical applications of the CANON process., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have influenced the work reported in this study., (Copyright © 2023 Elsevier B.V. All rights reserved.)

An anaerobic, Gram-positive, rod-shaped, motile and spore-forming bacterium, designated strain ZCY20-5 T , was isolated from pit clay of Chinese strong-aroma type Baijiu (Chinese liquor). Phylogenetic analyses based on 16S rRNA gene and genome sequences showed that strain ZCY20-5 T belonged to the genus Caproicibacterium , family Oscillospiracheae , but it showed low similarity to the type species Caproicibacterium amylolyticum LBM18003 T (98.00 %) and Caproicibacterium lactatifermentans LBM19010 T (95.67 %). In anaerobic yeast extract medium, growth was observed at 20-45 °C (optimum, 35-40 °C), at pH 4.0-9.0 (optimum, pH 6.5-7.0) and with 0.0-2.0 % NaCl (w/v). The predominant fatty acids were C 16 : 0 , C 14 : 0 , C 13 3-OH and C 16 3-OH, and the major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, three phospholipids of unknown structure containing glucosamine and two unidentified phospholipids. Strain ZCY20-5 T exhibited an 81.32 % pairwise average nucleotide identity value, a 78.98 % average amino acid identity value and a 22.30 % digital DNA-DNA hybridization value compared to its closest relative C. amylolyticum LBM18003 T . Based on morphological, physiological, biochemical, chemotaxonomic, genotypic and phylogenetic results, strain ZCY20-5 T represents a novel species of Caproicibacterium , and the type strain is ZCY20-5 T (=MCCC 1A19399 T =KCTC 25590 T ).

Importance: The microbial diversity in polymicrobial infections (PMIs) allows for community members to establish interactions with one another, which can result in enhanced disease outcomes such as increased antibiotic tolerance and chronicity. Chronic PMIs result in large burdens on health systems, as they affect a significant proportion of the population and are expensive and difficult to treat. However, investigations into physiology of microbial communities in actual human infection sites are lacking. Here, we highlight that the predominant functions in chronic PMIs differ, and anaerobes, often described as bystanders, may be significant in the progression of chronic infections. Determining the community structure and functions in PMIs is a critical step toward understanding the molecular mechanisms that increase the virulence potential of the microbial community in these environments., Competing Interests: The authors declare no conflict of interest.

Enrichment of anaerobic ammonium oxidizing bacteria (AnAOB) in the anaerobic ammonium oxidation (anammox) process remains a challenge in engineering applications. In this study, for faster enrichment of AnAOB, red mud-based carriers were positively charged with FeCl 3 and microbial promoters. The experimental results showed that the average nitrogen removal rates of the red mud-based carriers (RMGA), FeCl 3 -modified red mud-based carriers (RMGA-Fe), and microbial promoter-modified red mud-based carriers (RMGA-MA) increased by 24.4%-175% compared with the commercially available K3 carriers. Combining the results of SEM and laser confocal microscope, electrostatic attraction played a leading role on loading AnAOB. The increase in the surface roughness and specific area of the carriers after the attachment and the presence of Fe 2+ , Ca 2+ , and Mg 2+ plasma were necessary for the subsequent growth of AnAOB, while the leaching of Cr(VI) promoted the nitrogen removal effect of AnAOB., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:Wenjie zhang reports financial support was provided by Guangxi Natural Science Foundation., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Infections from anaerobic microorganisms result from breached mucosal barriers, posing a significant mortality risk. A retrospective study at Hospital Universitario La Paz (Madrid) from 2010 to 2022 analyzed 491 (6.17 %) anaerobic bacteremia cases out of 7956 significant bacteremia cases among 171,833 blood culture requests. Bacteroides fragilis was the most frequently isolated species (28.3 %), followed by Clostridium perfringens (13.6 %). B. fragilis showed good susceptibility to amoxicillin/ clavulanic acid (86 %), piperacillin/tazobactam (86 %), and metronidazole (87.7 %). In general, non-fragilis Bacteroides species showed low susceptibility to penicillin (7 %), amoxicillin (17.5 %), and clindamycin (64.9 %). Of our 13 non-perfringens Clostridium isolates, four exhibited resistance to penicillin and four showed resistance to clindamycin. Lactobacillus species were highly susceptible to antibiotics tested. Prevotella spp. showed low susceptibility to penicillin (20 %), amoxicillin (20 %), and clindamycin (40 %). The study contributes valuable data for monitoring and improving anaerobic bacteremia treatment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

The cycle of life and death and Earth's carbon cycle(s) are intimately linked, yet how bacterial cells, one of the largest pools of biomass on Earth, are recycled back into the carbon cycle remains enigmatic. In particular, no bacteria capable of scavenging dead cells in oxygen-depleted environments have been reported thus far. In this study, we discover the first anaerobes that scavenge dead cells and the two isolated strains use distinct strategies. Based on live-cell imaging, transmission electron microscopy, and hydrolytic enzyme assays, one strain (designated CYCD) relied on cell-to-cell contact and cell invagination for degrading dead food bacteria where as the other strain (MGCD) degraded dead food bacteria via excretion of lytic extracellular enzymes. Both strains could degrade dead cells of differing taxonomy (bacteria and archaea) and differing extents of cell damage, including those without artificially inflicted physical damage. In addition, both depended on symbiotic metabolic interactions for maximizing cell degradation, representing the first cultured syntrophic Bacteroidota. We collectively revealed multiple symbiotic bacterial decomposition routes of dead prokaryotic cells, providing novel insight into the last step of the carbon cycle., (© 2023. The Author(s), under exclusive licence to International Society for Microbial Ecology.)

Objective: The family Lachnospiraceae is affiliated with the order Clostridiales and was originally contained within Clostridial cluster XIVa. The members of Lachnospiraceae inhabiting the gut comprise the chemoorganotrophic genera, generating sundry short-chain fatty acids to supply energy to the host, and are considered to be related to obesity and gut health., Methods: The polyphasic taxonomic approach was used to characterize the isolate YH-rum2234 T . A detailed metabolic analysis was conducted to compare the novel isolate with related strains within the family Lachnospiraceae., Results: A fusiform, obligately anaerobic, Gram-stain-negative bacterium, YH-rum2234 T , was isolated from pig feces. Analysis of the 16S rRNA gene sequence revealed that the similarities between the isolate and the familiarly interrelated strain Lientehia hominis KCTC 25345 T was 94.3%. The average nucleotide identities and genome-to-genome distances of YH-rum2234 T and its closely related strains were below 85.5% and 32.5%, respectively. The G + C content of the genomic DNA was 49.2 mol%. The main fatty acids were C 16:0 , C 14:0 , and C 14:0 DMA. The major polar lipids were aminophospholipids. The cell wall did not contain the peptidoglycan meso-diaminopimelic acid., Conclusion: Given the chemotaxonomic, phenotypic, and phylogenetic properties, YH-rum2234 T (=KCTC 25710 T  = DSMZ 116041 T ) represents a new genus and species in the family Lachnospiraceae. Fusibacillus kribbianus gen. nov., sp. nov. is the proposed name., Competing Interests: Declaration of competing interest 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 © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Introduction: Even in present-day times, cancer is one of the most fatal diseases. People are overwhelmed by pricey chemotherapy, immunotherapy, and other costly cancer therapies in poor and middle-income countries. Cancer cells grow under anaerobic and hypoxic conditions. Pyruvate is the final product of the anaerobic glycolysis pathway, and many cancer cells utilize pyruvate for their growth and development. The anaerobic microbiome produces many anti-cancer substances that can act as anti-tumor agents and are both feasible and of low cost. There are different mechanisms of action of the anaerobic microbiome, such as the production of short-chain fatty acids (SCFAs), and competition for the anaerobic environment includes the metabolic product pyruvate to form lactic acid for energy., Key Findings: In this review, we have summarized the role of the metabolic approach of the anaerobic human microbiome in cancer prevention and treatment by interfering with cancer metabolite pyruvate. SCFAs possess decisive outcomes in condoning almost all the hallmarks of cancer and helping the spread of cancer to other body parts. Studies have demonstrated the impact and significance of using SCFA, which results from anaerobic bacteria, as an anti-cancer agent. Anaerobic bacteria-based cancer therapy has become a promising approach to treat cancer using obligate and facultative anaerobic bacteria because of their ability to penetrate and increase in an acidic hypoxic environment., Significance: This review attempts to provide the interconnection of cancer metabolism and anaerobic microbiome metabolism with a focus on pyruvate metabolism to understand and design unique anaerobic microbiota-based therapy for cancer patients., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Objectives: The purpose of this study is to evaluate the usefulness of anaerobic blood culture in pediatric patients by comparing the detection rate and distribution of bacteria between aerobic and anaerobic blood culture bottles., Methods: A retrospective analysis was conducted on 11,664 blood cultures obtained from children under the age of 14 between January 2013 and June 2020. The positive rate of total, aerobic, and anaerobic blood culture, as well as the species distribution of each blood culture bottle, were investigated., Results: The positive rate of blood culture was 2.4 % (N = 281). Among them, 67 (23.8 %), 85 (30.3 %) and 129 (45.9 %) organisms were grown in only aerobic, only anaerobic, and both blood culture bottles, respectively. Gram-positive cocci were cultured on both, only aerobic, and only anaerobic blood culture bottles in proportions of 46.4 %, 23.4 %, and 30.2 %, respectively. Gram-negative bacilli were cultured on both, only aerobic, and only anaerobic blood culture bottles in proportions of 58.5 %, 12,3 %, and 29.2 %, respectively. Gram-positive bacilli grew best in aerobic bottle only. There were seven strains of obligate anaerobes., Conclusion: Because many facultative anaerobic bacteria are recognized primarily from anaerobic blood culture bottles, combining aerobic and anaerobic blood culture bottles might be beneficial in pediatric patients with suspected blood stream infection., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

A wide diversity of microorganisms, typically growing as biofilms, has been implicated in corrosion, a multi-trillion dollar a year problem. Aerobic microorganisms establish conditions that promote metal corrosion, but most corrosion has been attributed to anaerobes. Microbially produced organic acids, sulfide and extracellular hydrogenases can accelerate metallic iron (Fe 0 ) oxidation coupled to hydrogen (H 2 ) production, as can respiratory anaerobes consuming H 2 as an electron donor. Some bacteria and archaea directly accept electrons from Fe 0 to support anaerobic respiration, often with c-type cytochromes as the apparent outer-surface electrical contact with the metal. Functional genetic studies are beginning to define corrosion mechanisms more rigorously. Omics studies are revealing which microorganisms are associated with corrosion, but new strategies for recovering corrosive microorganisms in culture are required to evaluate corrosive capabilities and mechanisms. Interdisciplinary studies of the interactions among microorganisms and between microorganisms and metals in corrosive biofilms show promise for developing new technologies to detect and prevent corrosion. In this Review, we explore the role of microorganisms in metal corrosion and discuss potential ways to mitigate it., (© 2023. Springer Nature Limited.)

The Clostridia is a dominant bacterial class in the guts of various animals and are considered to nutritionally contribute to the animal host. Here, we discovered clostridial endosymbionts of cellulolytic protists in termite guts, which have never been reported with evidence. We obtained (near-)complete genome sequences of three endosymbiotic Clostridia, each associated with a different parabasalid protist species with various infection rates: Trichonympha agilis, Pseudotrichonympha grassii, and Devescovina sp. All these protists are previously known to harbor permanently-associated, mutualistic Endomicrobia or Bacteroidales that supplement nitrogenous compounds. The genomes of the endosymbiotic Clostridia were small in size (1.0-1.3 Mbp) and exhibited signatures of an obligately-intracellular parasite, such as an extremely limited capability to synthesize amino acids, cofactors, and nucleotides and a disrupted glycolytic pathway with no known net ATP-generating system. Instead, the genomes encoded ATP/ADP translocase and, interestingly, regulatory proteins that are unique to eukaryotes in general and are possibly used to interfere with host cellular processes. These three genomes formed a clade with metagenome-assembled genomes (MAGs) derived from the guts of other animals, including human and ruminants, and the MAGs shared the characteristics of parasites. Gene flux analysis suggested that the acquisition of the ATP/ADP translocase gene in a common ancestor was probably key to the emergence of this parasitic clade. Taken together, we provide novel insights into the multilayered symbiotic system in the termite gut by adding the presence of parasitism and present an example of the emergence of putative energy parasites from a dominant gut bacterial clade., (© 2023. The Author(s).)

A novel anaerobic heterotrophic bacterium, designated strain SWIR-1 T , was isolated from a deep-sea hydrothermal vent field sample collected from the Southwest Indian Ridge at a depth of 2700 m. Phylogenetic analysis indicated that strain SWIR-1 T belongs to the genus Tepidibacter , and the most closely related species are Tepidibacter mesophilus B1 T (99.1 % 16S rRNA gene sequence similarity), Tepidibacter formicigenes DV1184 T (94.6 %) and Tepidibacter thalassicus SC562 T (93.9 %). Strain SWIR-1 T shares 77.3-87.2 % average nucleotide identity and 21.5-35.7 % digital DNA-DNA hybridization values with the three type strains of Tepidibacter species. Cells of strain SWIR-1 T were Gram-stain-positive, motile, short straight rods. Endospores were observed in stationary-phase cells when grown on Thermococcales rich medium. Strain SWIR-1 T grew at 15-45 °C (optimum, 30°C), at pH 5.5-8.0 (optimum, pH 7.0) and with 1.0-6.0 % (w/v) NaCl (optimum, 2.0 %). Substrates utilized by strain SWIR-1 T included complex proteinaceous, chitin, starch, lactose, maltose, fructose, galactose, glucose, rhamnose, arabinose, ribose, alanine, glycine and glycerol. The major fermentation products from glucose were acetate, lactate, H 2 and CO 2 . Elemental sulphur, sulphate, thiosulphate, sulphite, fumarate, nitrate, nitrite and FeCl 3 are not used as terminal electron acceptors. The main cellular fatty acids consisted of iso-C 15 : 0 (28.4 %), C 15 : 1 iso F (15.4 %) and C 16 : 0 (9.8 %). The major polar lipids were phospholipids and glycolipids. No respiratory quinones were detected. Genomic comparison revealed a distinctive blended gene cluster comprising hyb-tat-hyp genes, which play a crucial role in the synthesis, maturation, activation and export of NiFe-hydrogenase. Based on the phylogenetic analysis, genomic, physiologic and chemotaxonomic characteristics, strain SWIR-1 T is considered to represent a novel species within the genus Tepidibacter , for which the name Tepidibacter hydrothermalis sp. nov. is proposed. The type strain is strain SWIR-1 T (=DSM 113848 T =MCCC 1K07078 T ).

Background: Anaerobes are normal flora of the human body. However, they can cause serious infections in humans. Anaerobic bacteria are known to cause respiratory infections like pneumonia and acute exacerbation of chronic lower airway infections. These are often missed due to the complexity of their isolation and identification. Hence, this study aimed to study anaerobes causing respiratory tract infections and determine their antibiotic susceptibility., Materials & Methods: Clinical specimens such as bronchial aspirates and pleural aspirates collected from patients with respiratory diseases attending Vallabhbhai Patel Chest Institute were processed, the anaerobes isolated were identified, and their susceptibilities to various groups of antimicrobials were studied using standard microbiological methods., Results: Three hundred and fourteen patients were included in the study, 154 males and 160 females. Of these 314 patients, 148 (47%) yielded anaerobes in their clinical samples. Seventy patients had more than one type of anaerobic organism. Hence, 235 isolates were recovered belonging to as many as 17 genera. The MIC of seven antibiotics on 154 isolates was tested. The isolates belonged mostly to the genera Bacteroides, Prevotella, Veillonella, and Actinomyces. Variable resistance was observed to most classes of antibiotics by many genera., Conclusions: Metronidazole is commonly used against anaerobes, but the study showed that the isolates were 20-30% resistant to the antibiotic. Starting this as an empirical therapy might lead to treatment failure., (© 2023. BioMed Central Ltd., part of Springer Nature.)