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Xanthorhodopsin (XR), a retinal-binding 7-transmembrane protein isolated from the eubacterium Salinibacter ruber, utilizes two chromophores (retinal and salinixanthin (SAL)) as an outward proton pump and energy-donating carotenoid. However, research on XR has been impeded owing to limitations in achieving heterogeneous expression of stable forms and high production levels of both wild-type and mutants. We successfully expressed wild-type and mutant XRs in Escherichia coli in the presence of K + . Achieving XR expression requires significant K + and a low inducer concentration. In particular, we highlight the significance of Ser-159 in helix E located near Gly-156 (a carotenoid-binding position) as a critical site for XR expression. Our findings indicate that replacing Ser-159 with a smaller amino acid, alanine, can enhance XR expression in a manner comparable to K + , implying that Ser-159 poses a steric hindrance for pigment formation in XR. In the presence of K + , the proton pumping and photocycle of the wild-type and mutants were characterized and compared; the wild-type result suggests similar properties to the first reported XR isolation from the S. ruber membrane fraction. We propose that the K + gradient across the cell membrane of S. ruber serves to uphold the membrane potential of the organism and plays a role in the expression of proteins, such as XR, as demonstrated in our study. Our findings deepen the understanding of adaptive protein expression, particularly in halophilic organisms. We highlight salt selection as a promising strategy for improving protein yield and functionality., Competing Interests: Declaration of competing interest The authors declare that they have no conflicts of interest with the contents of this article., (Copyright © 2023. Published by Elsevier B.V.)

Access to safe drinking water sources and appropriate sanitation facilities remains a dream in low and middle-income countries including South Africa. This study identified the origin of faecal pollution by using quantitative polymerase chain reaction (qPCR) targeting host-specific Bacteroidales genetic markers to track the distribution of human-specific (BacHum) and animal-specific (cattle-BacCow, chicken-Cytb, pig-Pig-2-Bac, dog-BacCan) markers in water sources used by rural communities of the Vhembe District Municipality (VDM). Results revealed the prevalence of BacHum, BacCow, and BacCan in all surface water sources in Thulamela Local Municipality (TLM) and Collins Chabane Local Municipality (CLM) during wet (100%) and dry seasons (50-75%). Cytb was not detected in untreated spring water in TLM and CLM, and Pig-2-Bac was not detected in untreated hand-dug well water in TLM during both seasons. Household-level analysis detected Cytb (28.8% wet, 17.5% dry), BacHum (34.4% wet, 25% dry for Pig-2-Bac) in stored untreated spring water in CLM, and Cytb (42.9% wet, 28.5% dry) in untreated hand-dug well water in TLM. Despite differences in detection frequencies of host-specific Bacteroidales, the study highlights the public health concern of faecal pollution in rural VDM households., (© 2024. The Author(s).)

Polygonatum kingianum Collett & Hemsl., is one of the most important traditional Chinese medicines in China. The purpose of this study is to investigate the relationship between herb quality and microbial-soil variables, while also examining the composition and structure of the rhizosphere microbial community in Polygonatum kingianum, the ultimate goal is to provide a scientific approach to enhancing the quality of P. kingianum. Illumina NovaSeq technology unlocks comprehensive genetic variation and biological functionality through high-throughput sequencing. And in this study it was used to analyze the rhizosphere microbial communities in the soils of five P. kingianum planting areas. Conventional techniques were used to measure the organic elements, pH, and organic matter content. The active ingredient content of P. kingianum was identified by High Performance Liquid Chromatography (HPLC) and Colorimetry. A total of 12,715 bacterial and 5487 fungal Operational Taxonomic Units (OTU) were obtained and taxonomically categorized into 81 and 7 different phyla. Proteobacteria, Bacteroidetes, and Acidobacteriae were the dominant bacterial phyla Ascomycota and Basidiomycota were the dominat fungal phyla. The key predictors for bacterial community structure included hydrolysable nitrogen and available potassium, while for altering fungal community structure, soil organic carbon content (OCC), total nitrogen content (TNC), and total potassium content (TPOC) were the main influencing factors. Bryobacter and Candidatus Solibacter may indirectly increase the polysaccharide content of P. kingianum, and can be developed as potential Plant Growth Promoting Rhizobacteria (PGPR). This study has confirmed the differences in the soil and microorganisms of different origins of P. kingianum, and their close association with its active ingredients. And it also broadens the idea of studying the link between plants and microorganisms., (© 2024. The Author(s).)

Plasmids are small DNA molecules that enable bacteria to share beneficial traits, influencing microbial communities. However, their role within the human gut microbiome remains largely unknown. In this study, we investigate the gut microbiomes of 34 mother-child cohorts, employing a plasmid analysis workflow to understand the impact of plasmids on the gut microbiome. We create a plasmid phylogenetic tree, devise a method for assigning plasmid hosts, and examine potential plasmid transfer networks. Our research discovers a wide variety of previously unidentified plasmid sequences, indicating that current databases do not fully represent the gut plasmidome. Interestingly, infants display greater plasmid diversity compared to mothers and other healthy adults. We find that Bacteroidota, a major bacterial phylum, serves as the primary host for gut plasmids and plays a dominant role in gut plasmid transfer events. Additionally, plasmids broaden the genetic capabilities of bacteria, with their influence on bacterial function becoming more apparent as children's gut microbiomes develop. This study sheds light on the role of plasmids in the infant gut microbiome, making a significant contribution to our understanding of plasmid biology., (© 2024. The Author(s).)

A mechanistic understanding of host-microbe interactions in the gut microbiome is hindered by poorly annotated bacterial genomes. While functional genomics can generate large gene-to-phenotype datasets to accelerate functional discovery, their applications to study gut anaerobes have been limited. For instance, most gain-of-function screens of gut-derived genes have been performed in Escherichia coli and assayed in a small number of conditions. To address these challenges, we develop Barcoded Overexpression BActerial shotgun library sequencing (Boba-seq). We demonstrate the power of this approach by assaying genes from diverse gut Bacteroidales overexpressed in Bacteroides thetaiotaomicron. From hundreds of experiments, we identify new functions and phenotypes for 29 genes important for carbohydrate metabolism or tolerance to antibiotics or bile salts. Highlights include the discovery of a D-glucosamine kinase, a raffinose transporter, and several routes that increase tolerance to ceftriaxone and bile salts through lipid biosynthesis. This approach can be readily applied to develop screens in other strains and additional phenotypic assays., (© 2024. The Author(s).)

The lag phase is key in resuming bacterial growth, but it remains underexplored particularly in environmental bacteria. Here we use transcriptomics and 13 C-labelled metabolomics to show that the lag phase of the model marine bacterium Phaeobacter inhibens is shortened by methylated compounds produced by the microalgal partner, Emiliania huxleyi. Methylated compounds are abundantly produced and released by microalgae, and we show that their methyl groups can be collected by bacteria and assimilated through the methionine cycle. Our findings underscore the significance of methyl groups as a limiting factor during the lag phase and highlight the adjustability of this growth phase. In addition, we show that methylated compounds, typical of photosynthetic organisms, prompt diverse reductions in lag times in bacteria associated with algae and plants, potentially favouring early growth in some bacteria. These findings suggest ways to accelerate bacterial growth and underscore the significance of studying bacteria within an environmental context., (© 2024. The Author(s).)

An arsenate reductase (Car1) from the Bacteroidetes species Rufibacter tibetensis 1351 T was isolated from the Tibetan Plateau. The strain exhibits resistance to arsenite [As(III)] and arsenate [As(V)] and reduces As(V) to As(III). Here we shed light on the mechanism of enzymatic reduction by Car1. AlphaFold2 structure prediction, active site energy minimization, and steady-state kinetics of wild-type and mutant enzymes give insight into the catalytic mechanism. Car1 is structurally related to calcineurin-like metallophosphoesterases (MPPs). It functions as a binuclear metal hydrolase with limited phosphatase activity, particularly relying on the divalent metal Ni 2+ . As an As(V) reductase, it displays metal promiscuity and is coupled to the thioredoxin redox cycle, requiring the participation of two cysteine residues, Cys74 and Cys76. These findings suggest that Car1 evolved from a common ancestor of extant phosphatases by incorporating a redox function into an existing MPP catalytic site. Its proposed mechanism of arsenate reduction involves Cys74 initiating a nucleophilic attack on arsenate, leading to the formation of a covalent intermediate. Next, a nucleophilic attack of Cys76 leads to the release of As(III) and the formation of a surface-exposed Cys74-Cys76 disulfide, ready for reduction by thioredoxin., (© 2024 John Wiley & Sons Ltd.)

The intestinal microbiota plays significant role in the physiology and functioning of host organisms. However, there is limited knowledge of the composition and evolution of microbiota-host relationships from wild ancestors to modern domesticated species. In this study, the 16S rRNA gene V3-V4 in the intestinal contents of different pig breeds was analyzed and was compared using high-throughput sequencing. This identified 18 323 amplicon sequence variants, of which the Firmicutes and Actinobacteria phyla and Bifidobacterium and Allobaculum genera were most prevalent in wild pigs (WP). In contrast, Proteobacteria and Firmicutes predominated in Chinese Shanxi Black pigs (CSB), while Firmicutes were the most prevalent phylum in Large White pigs (LW) and Iberian pigs (IB), followed by Bacteroidetes in IB and Proteobacteria in LW. At the genus level, Shigella and Lactobacillus were most prevalent in CSB and LW, while Actinobacillus and Sarcina predominated in IB. Differential gene expression together with phylogenetic and functional analyses indicated significant differences in the relative abundance of microbial taxa between different pig breeds. Although many microbial taxa were common to both wild and domestic pigs, significant diversification was observed in bacterial genes that potentially influence host phenotypic traits. Overall, these findings suggested that both the composition and functions of the microbiota were closely associated with domestication and the evolutionary changes in the host. The members of the microbial communities were vertically transmitted in pigs, with evidence of co-evolution of both the hosts and their intestinal microbial communities. These results enhance our understanding and appreciation of the complex interactions between intestinal microbes and hosts and highlight the importance of applying this knowledge in agricultural and microbiological research., (© 2023. The Author(s).)

S tarch u tilization s ystem (Sus)D-homologs are well known for their carbohydrate-binding capabilities and are part of the sus operon in microorganisms affiliated with the phylum Bacteroidota. Until now, SusD-like proteins have been characterized regarding their affinity toward natural polymers. In this study, three metagenomic SusD homologs (designated SusD1, SusD38489, and SusD70111) were identified and tested with respect to binding to natural and non-natural polymers. SusD1 and SusD38489 are cellulose-binding modules, while SusD70111 preferentially binds chitin. Employing translational fusion proteins with superfolder GFP (sfGFP), pull-down assays, and surface plasmon resonance (SPR) has provided evidence for binding to polyethylene terephthalate (PET) and other synthetic polymers. Structural analysis suggested that a Trp triad might be involved in protein adsorption. Mutation of these residues to Ala resulted in an impaired adsorption to microcrystalline cellulose (MC), but not so to PET and other synthetic polymers. We believe that the characterized SusDs, alongside the methods and considerations presented in this work, will aid further research regarding bioremediation of plastics., Importance: SusD1 and SusD38489 can be considered for further applications regarding their putative adsorption toward fossil-fuel based polymers. This is the first time that SusD homologs from the polysaccharide utilization loci (PUL), largely described for the phylum Bacteroidota, are characterized as synthetic polymer-binding proteins., Competing Interests: The authors declare no conflict of interest.

Structural color is an optical phenomenon resulting from light interacting with nanostructured materials. Although structural color (SC) is widespread in the tree of life, the underlying genetics and genomics are not well understood. Here, we collected and sequenced a set of 87 structurally colored bacterial isolates and 30 related strains lacking SC. Optical analysis of colonies indicated that diverse bacteria from at least two different phyla ( Bacteroidetes and Proteobacteria ) can create two-dimensional packing of cells capable of producing SC. A pan-genome-wide association approach was used to identify genes associated with SC. The biosynthesis of uroporphyrin and pterins, as well as carbohydrate utilization and metabolism, was found to be involved. Using this information, we constructed a classifier to predict SC directly from bacterial genome sequences and validated it by cultivating and scoring 100 strains that were not part of the training set. We predicted that SCr is widely distributed within gram-negative bacteria. Analysis of over 13,000 assembled metagenomes suggested that SC is nearly absent from most habitats associated with multicellular organisms except macroalgae and is abundant in marine waters and surface/air interfaces. This work provides a large-scale ecogenomics view of SC in bacteria and identifies microbial pathways and evolutionary relationships that underlie this optical phenomenon., Competing Interests: Competing interests statement:The author C.J.I. and others affiliated to Hoekmine BV are developing materials from structurally coloured bacteria. However, this is a separate activity from the academic work presented here.

Background: Soybean cyst nematodes (SCN) as animal parasites of plants are not usually interested in killing the host but are rather focused on completing their life cycle to increase population, resulting in substantial yield losses. Remarkably, some agricultural soils after long-term crop monoculture show a significant decline in SCN densities and suppress disease in a sustainable and viable manner. However, relatively little is known about the microbes and mechanisms operating against SCN in such disease-suppressive soils., Results: Greenhouse experiments showed that suppressive soils (S) collected from two provinces of China and transplantation soils (CS, created by mixing 10% S with 90% conducive soils) suppressed SCN. However, SCN suppressiveness was partially lost or completely abolished when S soils were treated with heat (80 °C) and formalin. Bacterial community analysis revealed that the specific suppression in S and CS was mainly associated with the bacterial phylum Bacteroidetes, specifically due to the enrichment of Chitinophaga spp. and Dyadobacter sp., in the cysts. SCN cysts colonized by Chitinophaga spp. showed dramatically reduced egg hatching, with unrecognizable internal body organization of juveniles inside the eggshell due to chitinase activity. Whereas, Dyadobacter sp. cells attached to the surface coat of J2s increased soybean resistance against SCN by triggering the expression of defence-associated genes. The disease-suppressive potential of these bacteria was validated by inoculating them into conducive soil. The Dyadobacter strain alone or in combination with Chitinophaga strains significantly decreased egg densities after one growing cycle of soybeans. In contrast, Chitinophaga strains alone required more than one growing cycle to significantly reduce SCN egg hatching and population density., Conclusion: This study revealed how soybean monoculture for decades induced microbiota homeostasis, leading to the formation of SCN-suppressive soil. The high relative abundance of antagonistic bacteria in the cyst suppressed the SCN population both directly and indirectly. Because uncontrolled proliferation will likely lead to quick demise due to host population collapse, obligate parasites like SCN may have evolved to modulate virulence/proliferation to balance these conflicting needs. Video Abstract., (© 2024. The Author(s).)

Background: The phylum Bacteroidota represents a significant proportion of heterotrophic bacteria found in marine ecosystems. Members of the phylum Bacteroidota are actively involved in the degradation of biopolymers such as polysaccharides and proteins. Bacteroidota genomes exhibit a significant enrichment of various enzymes, including carbohydrate-active enzymes (CAZymes), carboxypeptidases, esterases, isomerases, peptidases, phosphatases, and sulfatases. The genus Marivirga, a member of the family Marivirgaceae within the phylum Bacteroidota, comprises six documented species. During a microbial diversity study, three novel Marivirga strains (BKB1-2  T , ABR2-2, and BDSF4-3  T ) were isolated from the West Sea, Republic of Korea., Results: To explore the taxonomic status and genomic characteristics of the novel isolates, we employed a polyphasic taxonomic approach, which included phylogenetic, chemotaxonomic and comprehensive genome analysis. The three isolates were Gram-stain-negative, aerobic, rod-shaped, moderately halophilic, and had a gliding motility. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values among the two isolates, BKB1-2  T and BDSF4-3  T , and the six reference strains were 70.5-76.5% for ANI and 18.1-25.7% for dDDH. Interestingly, the Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that the strains harbor genes for a comprehensive pathway for dissimilatory nitrate reduction to ammonium (DNRA), as well as other nitrogen pathways for the reduction of nitrite, nitric oxide, and nitrous oxide. Additionally, the antiSMASH analysis indicated that the strains contained three to eight biosynthetic gene clusters (BGCs) associated with the synthesis of secondary metabolites. Furthermore, the strains carried a high number of CAZyme ranging from 53 to 152, which was also demonstrated by an in vitro analysis of degradation of the polysaccharide cellulose, chitin, laminarin, starch, and xylan. Additionally, all the strains carried genes for the metabolism of heavy metals, and exhibited tolerance to heavy metals, with minimum inhibitory concentrations (MICs) in millimoles (mM) in ranges of Co 2+ (3-6), Cu 2+ (0.2-0.4), Ni 2+ (3-5), Zn 2+ (2-4), Mn 2+ (20-50), and Hg 2+ (0.3)., Conclusions: Based on polyphasic taxonomic approach, the three isolated strains represent two novel species names Marivirga arenosa sp. nov. (BKB1-2  T  = KCTC 82989  T  = InaCC B1618 T ), and Marivirga salinae sp. nov. (BDSF4-3  T  = KCTC 82973  T  = InaCC B1619 T )., (© 2024. The Author(s).)

Introduction: In this study, the seasonal differences in the intestinal microbiota of Chinese mitten crab ( Eriocheir sinensis ) larvae were investigated at different sites in the intertidal zone of the Yangtze River Estuary., Methods: 16S rRNA high-throughput sequencing technology was used to compare and analyze the microbial community structure in the intestines of juvenile crab from different seasons., Results: The results showed that the main microbial phyla in all seasons and sites were Proteobacteria, Bacteroidetes, Firmicutes, and Actinobacteria, which accounted for 97.1% of the total microbiota. Composition analysis revealed that the relative abundance of Proteobacteria decreased from summer to winter at each station, whereas Bacteroidetes showed the opposite trend. Alpha diversity analysis showed that species richness increased from summer to winter at the upstream site ( P < 0.05), but decreased at the downstream site ( P < 0.05), with no significant differences observed in other comparisons. Biomarker species analysis showed that juvenile crab exhibited a more specialized microbial community in summer compared with autumn and winter. Co-occurrence network analysis revealed that microbial interaction network complexity was lower in autumn compared with summer and autumn. Functional prediction analysis showed that the microbial community only exhibited seasonal differences in amino acid biosynthesis, cofactor, prosthetic group, electron carrier, and vitamin biosynthesis, aromatic compound degradation, nucleotide and nucleoside degradation, and tricarboxylic acid cycle pathways., Discussion: The results indicated that the microbiota did not significantly differ among sites, and seasonal variation was a main factor influencing the differences in intestinal microbiota of Chinese mitten juvenile crab. Moreover, the microbial community was more complex in summer compared with autumn and winter., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Qin, Wang, Wu, Sun and Zhao.)

Objective: Bladder cancer(BCa) was a disease that seriously affects patients' quality of life and prognosis. To address this issue, many researches suggested that the gut microbiota modulated tumor response to treatment; however, this had not been well-characterized in bladder cancer. In this study, our objective was to determine whether the diversity and composition of the gut microbiota or the density of specific bacterial genera influence the prognosis of patients with bladder cancer., Methods: We collected fecal samples from a total of 50 bladder cancer patients and 22 matched non-cancer individuals for 16S rDNA sequencing to investigate the distribution of Parabacteroides in these two groups. Further we conducted follow-up with cancer patients to access the impact of different genera of microorganisms on patients survival. We conducted a Fecal Microbiota Transplantation (FMT) and mono-colonization experiment with Parabacteroides distasonis to explore its potential enhancement of the efficacy of anti-PD-1 immunotherapy in MB49 tumor-bearing mice. Immunohistochemistry, transcriptomics and molecular experiment analyses were employed to uncover the underlying mechanisms., Results: The 16S rDNA showed that abundance of the genus Parabacteroides was elevated in the non-cancer control group compared to bladder cancer group. The results of tumor growth curves showed that a combination therapy of P. distasonis and ICIs treatment significantly delayed tumor growth and increased the intratumoral densities of both CD4 + T and CD8 + T cells. The results of transcriptome analysis demonstrated that the pathways associated with antitumoral immune response were remarkably upregulated in the P. distasonis gavage group., Conclusion: P. distasonis delivery combined with α-PD-1 mAb could be a new strategy to enhance the effect of anti-PD-1 immunotherapy. This effect might be achieved by activating immune and antitumor related pathways., (© 2024. The Author(s).)

Heterotrophic microbial communities play a significant role in driving carbon fluxes in marine ecosystems. Despite their importance, these communities remain understudied in remote polar oceans, which are known for their substantial contribution to the biological drawdown of atmospheric carbon dioxide. Our research focused on understanding the environmental factors and genetic makeup of key bacterial players involved in carbon remineralization in the Weddell Sea, including its coastal polynyas. Our experiments demonstrated that the combination of labile organic matter supply and temperature increase synergistically boosted bacterial growth. This suggests that, besides low seawater temperature, carbon limitation also hinders heterotrophic bacterial activity. Through the analysis of metagenome-assembled genomes, we discovered distinct genomic adaptation strategies in Bacteroidia and Gammaproteobacteria, both of which respond to organic matter. Both natural phytoplankton blooms and experimental addition of organic matter favoured Bacteroidia, which possess a large number of gene copies and a wide range of functional membrane transporters, glycoside hydrolases, and aminopeptidases. In contrast, the genomes of organic-matter-responsive Gammaproteobacteria were characterized by high densities of transcriptional regulators and transporters. Our findings suggest that bacterioplankton in the Weddell Sea, which respond to organic matter, employ metabolic strategies similar to those of their counterparts in temperate oceans. These strategies enable efficient growth at extremely low seawater temperatures, provided that organic carbon limitation is alleviated., (© 2024 The Author(s). Environmental Microbiology published by John Wiley & Sons Ltd.)

A Gram-stain-negative, yellow-pigmented, and facultatively aerobic bacterium, designated strain GPA1 T , was isolated from plastic waste landfill soil in the Republic of Korea. The cells were non-motile short rods exhibiting oxidase-negative and catalase-positive activities. Growth was observed at 15-40 °C (optimum, 30 °C), at pH 6.0-9.0 (optimum, pH 7.0-8.0) and in the presence of 0-2.5 % (w/v) NaCl (optimum, 0 %). Menaquinone-7 was the sole respiratory quinone, and iso-C 15 : 0 , C 16 : 1  ω 5 c , and iso-C 17 : 0 3-OH were the major cellular fatty acids (>10 % of the total fatty acids). Phosphatidylethanolamine was identified as a major polar lipid. Phylogenetic analyses based on 16S rRNA gene sequences and 120 concatenated marker protein sequences revealed that strain GPA1 T formed a distinct lineage within the genus Chitinophaga . The genome of strain GPA1 T was 6078 kb in size with 53.8 mol% G+C content. Strain GPA1 T exhibited the highest similarity to Chitinophaga rhizosphaerae T16R-86 T , with a 98.6 % 16S rRNA gene sequence similarity, but their average nucleotide identity and digital DNA-DNA hybridization values were 82.5 and 25.9 %, respectively. Based on its phenotypic, chemotaxonomic, and phylogenetic characteristics, strain GPA1 T represents a novel species of the genus Chitinophaga , for which the name Chitinophaga pollutisoli sp. nov. is proposed. The type strain is GPA1 T (=KACC 23415 T =JCM 36644 T ).

Recent research has revealed that alterations of the gut microbiome (GM) play a comprehensive role in the pathophysiology of HF. However, findings in this field remain controversial. In this study, we focus on differences in GM diversity and abundance between HF patients and non-HF people, based on previous 16 S ribosomal RNA (16rRNA) gene sequencing. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we conducted a comprehensive search of PubMed, Web of Science, Embase, Cochrane Library, and Ovid databases using the keyword "Heart failure" and "Gastrointestinal Microbiome". A significant decrease in alpha diversity was observed in the HF patients (Chao1, I 2  = 87.5 %, p < 0.001; Shannon index, I 2  = 62.8 %, p = 0.021). At the phylum level, the HF group exhibited higher abundances of Proteobacteria (I 2  = 92.0 %, p = 0.004) and Actinobacteria (I 2  = 82.5 %, p = 0.010), while Bacteroidetes (I 2  = 45.1 %, p = 0.017) and F/B ratio (I 2  = 0.0 %, p＜0.001) were lower. The Firmicutes showed a decreasing trend but did not reach statistical significance (I 2  = 82.3 %, p = 0.127). At the genus level, the relative abundances of Streptococcus, Bacteroides, Alistipes, Bifidobacterium, Escherichia-Shigella, Enterococcus and Klebsiella were increased in the HF group, whereas Ruminococcus, Faecalibacterium, Dorea and Megamona exhibited decreased relative abundances. Dialister, Blautia and Prevotella showed decreasing trends but without statistical significance. This observational meta-analysis suggests that GM changes are associated with HF, manifesting as alterations in GM abundance, disruptions in the production of short-chain fatty acids (SCFAs) bacteria, and an increase in trimethylamine N-oxide (TMAO) producing bacteria., 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.)

Proteins featuring the Domain of Unknown Function 1735 are frequently found in Polysaccharide Utilization Loci, yet their role remains unknown. The domain and vicinity analyzer programs we developed mine the Kyoto Encyclopedia of Genes and Genomes and UniProt to enhance the functional prediction of DUF1735. Our datasets confirmed the exclusive presence of DUF1735 in Bacteroidota genomes, with Bacteroidetes thetaiotaomicron harboring 46 copies. Notably, 97.8% of DUF1735 are encoded in PULs, and 89% are N-termini of multimodular proteins featuring C-termini like Laminin&#95;G&#95;3, F5/8-typeC, and GH18 domains. Predominantly possessing a predicted lipoprotein signal peptide and sharing an immunoglobulin-like β-sandwich fold with the BACON domain and the N-termini of SusE/F, DUF1735 likely functions as N-terminal, membrane-bound spacer for diverse C-termini involved in PUL-mediated carbohydrate utilization., (© 2024 The Authors. FEBS Open Bio published by John Wiley & Sons Ltd on behalf of Federation of European Biochemical Societies.)

The accumulating evidence substantiates the indispensable role of gut microbiota in modulating the pathogenesis of type 2 diabetes. Uncovering the intricacies of the mechanism is imperative in aiding disease control efforts. Revealing key bacterial species, their metabolites and/or metabolic pathways from the vast array of gut microorganisms can significantly contribute to precise treatment of the disease. With a high prevalence of type 2 diabetes in Inner Mongolia, China, we recruited volunteers from among the Mongolian population to investigate the relationship between gut microbiota and the disease. Fecal samples were collected from the Volunteers of Mongolia with Type 2 Diabetes group and a Control group, and detected by metagenomic analysis and untargeted metabolomics analysis. The findings suggest that Firmicutes and Bacteroidetes phyla are the predominant gut microorganisms that exert significant influence on the pathogenesis of type 2 diabetes in the Mongolian population. In the disease group, despite an increase in the quantity of most gut microbial metabolic enzymes, there was a concomitant weakening of gut metabolic function, suggesting that the gut microbiota may be in a compensatory state during the disease stage. β-Tocotrienol may serve as a pivotal gut metabolite produced by gut microorganisms and a potential biomarker for type 2 diabetes. The metabolic biosynthesis pathways of ubiquinone and other terpenoid quinones could be the crucial mechanism through which the gut microbiota regulates type 2 diabetes. Additionally, certain Clostridium gut species may play a pivotal role in the progression of the disease.

Culture-dependent and metagenomic binning techniques were employed to gain an insight into the diversification of gut bacteria in Rhinopithecius bieti, a highly endangered primate endemic to China. Our analyses revealed that Bacillota&#95;A and Bacteroidota were the dominant phyla. These two phyla species are rich in carbohydrate active enzymes, which could provide nutrients and energy for their own or hosts' survival under different circumstances. Among the culturable bacteria, one novel bacterium, designated as WQ 2009 T , formed a distinct branch that had a low similarity to the known species in the family Sphingobacteriaceae, based on the phylogenetic analysis of its 16S rRNA gene sequence or phylogenomic analysis. The ANI, dDDH and AAI values between WQ 2009 T and its most closely related strains S. kitahiroshimense 10C T , S. pakistanense NCCP-246 T and S. faecium DSM 11690 T were significantly lower than the accepted cut-off values for microbial species delineation. All results demonstrated that WQ 2009 T represent a novel genus, for which names Rhinopithecimicrobium gen. nov. and Rhinopithecimicrobium faecis sp. nov. (Type strain WQ 2009 T  = CCTCC AA 2021153 T  = KCTC 82941 T ) are proposed., (© 2024. The Author(s).)

Background: Spodoptera frugiperda , the fall armyworm is a destructive invasive pest, and S. litura the tobacco cutworm, is a native species closely related to S. frugiperda . The gut microbiota plays a vital role in insect growth, development, metabolism and immune system. Research on the competition between invasive species and closely related native species has focused on differences in the adaptability of insects to the environment. Little is known about gut symbiotic microbe composition and its role in influencing competitive differences between these two insects., Methods: We used a culture-independent approach targeting the 16S rRNA gene of gut bacteria of 5th instar larvae of S. frugiperda and S. litura . Larvae were reared continuously on maize leaves for five generations. We analyzed the composition, abundance, diversity, and metabolic function of gut microbiomes of S. frugiperda and S. litura larvae., Results: Firmicutes, Proteobacteria, and Bacteroidetes were the dominant bacterial phyla in both species. Enterococcus , ZOR0006 , Escherichia , Bacteroides , and Lactobacillus were the genera with the highest abundance in S. frugiperda . Enterococcus , Erysipelatoclostridium , ZOR0006 , Enterobacter , and Bacteroides had the highest abundance in S. litura . According to α -diversity analysis, the gut bacterial diversity of S. frugiperda was significantly higher than that of S. litura . KEGG analysis showed 15 significant differences in metabolic pathways between S. frugiperda and S. litura gut bacteria, including transcription, cell growth and death, excretory system and circulatory system pathways., Conclusion: In the same habitat, the larvae of S. frugiperda and S. litura showed significant differences in gut bacterial diversity and community composition. Regarding the composition and function of gut bacteria, the invasive species S. frugiperda may have a competitive advantage over S. litura . This study provides a foundation for developing control strategies for S. frugiperda and S. litura ., Competing Interests: The authors declare there are no competing interests., (©2024 Chen et al.)

Laccases (EC 1.10.3.2) are oxidoreductases that belong to the multicopper oxidase subfamily and are classified as yellow/white or blue according to their absorption spectrum. Yellow laccases are more useful for industrial processes since they oxidize nonphenolic compounds in the absence of a redox mediator and stand out for being more stable and functional under extreme conditions. This study aimed to characterize a new laccase that was predicted to be present in the genome of Chitinophaga sp. CB10 - Lac&#95;CB10. Lac&#95;CB10, with a molecular mass of 100.06 kDa, was purified and characterized via biochemical assays using guaiacol as a substrate. The enzyme demonstrated extremophilic characteristics, exhibiting relative activity under alkaline conditions (CAPS buffer pH 10.5) and thermophilic conditions (80-90°C), as well as maintaining its activity above 50% for 5 h at 80°C and 90°C. Furthermore, Lac&#95;CB10 presented a spectral profile typical of yellow laccases, exhibiting only one absorbance peak at 300 nm (at the T2/T3 site) and no peak at 600 nm (at the T1 site). When lignin was degraded using copper as an inducer, 52.27% of the material was degraded within 32 h. These results highlight the potential of this enzyme, which is a novel yellow laccase with thermophilic and alkaline activity and the ability to act on lignin. This enzyme could be a valuable addition to the biorefinery process. In addition, this approach has high potential for industrial application and in the bioremediation of contaminated environments since these processes often occur at extreme temperatures and pH values., Importance: The characterization of the novel yellow laccase, Lac&#95;CB10, derived from Chitinophaga sp. CB10, represents a significant advancement with broad implications. This enzyme displays exceptional stability and functionality under extreme conditions, operating effectively under both alkaline (pH 10.5) and thermophilic (80-90°C) environments. Its capability to maintain considerable activity over extended periods, even at high temperatures, showcases its potential for various industrial applications. Moreover, its distinctive ability to efficiently degrade lignin-demonstrated by a significant 52.27% degradation within 32 h-signifies a promising avenue for biorefinery processes. This newfound laccase's characteristics position it as a crucial asset in the realm of bioremediation, particularly in scenarios involving contamination at extreme pH and temperature levels. The study's findings highlight the enzyme's capacity to address challenges in industrial processes and environmental cleanup, signifying its vital role in advancing biotechnological solutions., Competing Interests: The authors declare no conflict of interest.

Extreme environments, such as Antarctica, select microbial communities that display a range of evolutionary strategies to survive and thrive under harsh environmental conditions. These include a diversity of specialized metabolites, which have the potential to be a source for new natural product discovery. Efforts using (meta)genome mining approaches to identify and understand biosynthetic gene clusters in Antarctica are still scarce, and the extent of their diversity and distribution patterns in the environment have yet to be discovered. Herein, we investigated the biosynthetic gene diversity of the biofilm microbial community of Whalers Bay, Deception Island, in the Antarctic Peninsula and revealed its distribution patterns along spatial and temporal gradients by applying metagenome mining approaches and multivariable analysis. The results showed that the Whalers Bay microbial community harbors a great diversity of biosynthetic gene clusters distributed into seven classes, with terpene being the most abundant. The phyla Proteobacteria and Bacteroidota were the most abundant in the microbial community and contributed significantly to the biosynthetic gene abundances in Whalers Bay. Furthermore, the results highlighted a significant correlation between the distribution of biosynthetic genes and taxonomic diversity, emphasizing the intricate interplay between microbial taxonomy and their potential for specialized metabolite production.IMPORTANCEThis research on antarctic microbial biosynthetic diversity in Whalers Bay, Deception Island, unveils the hidden potential of extreme environments for natural product discovery. By employing metagenomic techniques, the research highlights the extensive diversity of biosynthetic gene clusters and identifies key microbial phyla, Proteobacteria and Bacteroidota, as significant contributors. The correlation between taxonomic diversity and biosynthetic gene distribution underscores the intricate interplay governing specialized metabolite production. These findings are crucial for understanding microbial adaptation in extreme environments and hold significant implications for bioprospecting initiatives. The study opens avenues for discovering novel bioactive compounds with potential applications in medicine and industry, emphasizing the importance of preserving and exploring these polyextreme ecosystems to advance biotechnological and pharmaceutical research., Competing Interests: The authors declare no conflicts of interest.

Researchers have extensively studied the effect of oxygen on the growth and survival of bacteria. However, the impact of oxygen on bacterial community structure, particularly its ability to select for taxa within the context of a complex microbial community, is still unclear. In a 21-day microcosm experiment, we investigated the effect of aerobic exposure on the fecal community structure and succession pattern in broiler, calf, and piglet feces ( n = 10 for each feces type). Bacterial diversity decreased and community structure changed rapidly in the broiler microbiome ( P < 0.001), while the fecal community of calves and piglets, which have higher initial diversity, was stable after initial exposure but decreased in diversity after 3 days ( P < 0.001). The response to aerobic exposure was host animal specific, but in all three animals, the change in community structure was driven by a decrease in anaerobic species, primarily belonging to Firmicutes and Bacteroidetes (except in broilers where Bacteroidetes increased), along with an increase in aerobic species belonging to Proteobacteria and Actinobacteria. Using random forest regression, we identified microbial features that predict aerobic exposure. In all three animals, host-beneficial Prevotella -related ASVs decreased after exposure, while ASVs belonging to Acinetobacter , Corynbacterium, and Tissierella were increased. The decrease of Prevotella was rapid in broilers but delayed in calves and piglets. Knowing when these pathobionts increase in abundance after aerobic exposure could inform farm sanitation practices and could be important in designing animal experiments that modulate the microbiome.IMPORTANCEThe fecal microbial community is contained within a dynamic ecosystem of interacting microbes that varies in biotic and abiotic components across different animal species. Although oxygen affects bacterial growth, its specific impact on the structure of complex communities, such as those found in feces, and how these effects vary between different animal species are poorly understood. In this study, we demonstrate that the effect of aerobic exposure on the fecal microbiota was host-animal-specific, primarily driven by a decrease in Firmicutes and Bacteroidetes, but accompanied by an increase in Actinobacteria, Proteobacteria, and other pathobionts. Interestingly, we observed that more complex communities from pig and cattle exhibited initial resilience, while a less diverse community from broilers displayed a rapid response to aerobic exposure. Our findings offer insights that can inform farm sanitation practices, as well as experimental design, sample collection, and processing protocols for microbiome studies across various animal species., Competing Interests: The authors declare no conflict of interest.

Gram-negative bacteria from the Bacteroidota phylum possess a type-IX secretion system (T9SS) for protein secretion, which requires cargoes to have a C-terminal domain (CTD). Structurally analysed CTDs are from Porphyromonas gingivalis proteins RgpB, HBP35, PorU and PorZ, which share a compact immunoglobulin-like antiparallel 3+4 β-sandwich (β1-β7). This architecture is essential as a P. gingivalis strain with a single-point mutant of RgpB disrupting the interaction of the CTD with its preceding domain prevented secretion of the protein. Next, we identified the C-terminus ('motif C-t.') and the loop connecting strands β3 and β4 ('motif Lβ3β4') as conserved. We generated two strains with insertion and replacement mutants of PorU, as well as three strains with ablation and point mutants of RgpB, which revealed both motifs to be relevant for T9SS function. Furthermore, we determined the crystal structure of the CTD of mirolase, a cargo of the Tannerella forsythia T9SS , which shares the same general topology as in Porphyromonas CTDs. However, motif Lβ3β4 was not conserved. Consistently, P. gingivalis could not properly secrete a chimaeric protein with the CTD of peptidylarginine deiminase replaced with this foreign CTD. Thus, the incompatibility of the CTDs between these species prevents potential interference between their T9SSs.

Introduction: Nonampullary duodenal epithelial tumors are rare, but their prevalence is increasing. Various gastrointestinal cancers have been associated with microbiomes. We evaluated the characteristics of the salivary and duodenal microbiomes of patients with nonampullary duodenal epithelial tumors., Methods: Saliva and biopsy samples from the duodenal bulb and descending portion were obtained from 15 patients with nonampullary duodenal epithelial tumors and 10 controls. Next-generation sequencing was performed to identify bacteria for comparison., Results: Saliva samples had higher Amplicon Sequence Variants (ASVs) and more observed species than duodenal samples. Saliva samples from patients with nonampullary duodenal epithelial tumor were dominated by Bacteroidetes and Prevotella, whereas Proteobacteria and Neisseria were dominant in the control samples. The relative abundance of bacteria was higher in patients with nonampullary duodenal epithelial tumors. Most bacteria were classified as bacteria of oral origin. Oribacterium and Stomatobaculum were significantly higher in the saliva, duodenal bulb, and descending portion of patients with nonampullary duodenal epithelial tumors., Conclusion: Patients with nonampullary duodenal epithelial tumors had different salivary and duodenal microbiomes than controls. Bacteria types differed between groups at each site, and most bacteria of oral origin were more abundant in patients with nonampullary duodenal epithelial tumors., Competing Interests: Conflict of Interest The authors have no conflicts of interest to declare., (Copyright © 2024 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.)

Polysaccharide-degrading bacteria are key participants in the global carbon cycle and algal biomass recycling. Herein, a polysaccharide lyase-producing strain HB226069 was isolated from Sargassum sp. from Qingge Port, Hainan, China. Results of the phylogenetic of the 16S rRNA gene and genotypic analysis indicated that the isolate should be classified as Microbulbifer thermotolerans. The whole genome is a 4,021,337 bp circular chromosome with a G+C content of 56.5%. Analysis of the predicted genes indicated that strain HB226069 encoded 161 carbohydrate-active enzymes (CAZymes), and abundant putative enzymes involved in polysaccharide degradation were predicted, including alginate lyase, fucosidase, agarase, xylanase, cellulase, pectate lyase, amylase, and chitinase. Three of the putative polysaccharide lyases from PL7 and PL17 families were involved in alginate degradation. The alginate lyases of strain HB226069 showed the maximum activity of 117.4 U/mL at 50 °C, pH 7.0, and 0.05 M FeCl 3 , while exhibiting the best stability at 30 °C and pH 7.0. The Thin Layer Chromatography (TLC) and Electrospray Ionization Mass Spectrometry (ESI-MS) analyses indicated that the alginate oligosaccharides (AOSs) degraded by the partially purified alginate lyases contained oligosaccharides of DP2-DP5 and monosaccharide while reacting for 36 h. The complete genome of M. thermotolerans HB226069 enriches our understanding of the mechanism of polysaccharide lyase production and supports its potential application in polysaccharide degradation., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Bacteria of the genera Xylanibacter and Segatella are among the most dominant groups in the rumen microbiota. They are characterized by the ability to utilize different hemicelluloses and pectin of plant cell-wall as well as plant energy storage polysaccharides. The degradation is possible with the use of cell envelope bound multiprotein apparatuses coded in polysaccharide utilization loci (PULs), which have been shown to be substrate specific. The knowledge of PUL presence in rumen Xylanibacter and Segatella based on bioinformatic analyses is already established and transcriptomic and genetic approaches confirmed predicted PULs for a limited number of substrates. In this study, we transcriptomically identified additional different PULs in Xylanibacter ruminicola KHP1 and Segatella bryantii TF1-3. We also identified substrate preferences and found that specific growth rate and extent of growth impacted the choice of substrates preferentially used for degradation. These preferred substrates were used by both strains simultaneously as judged by their PUL upregulation. Lastly, β-glucan and xyloglucan were used by these strains in the absence of bioinformatically and transcriptomically identifiable PUL systems., (© 2024. The Author(s).)

Paddlefish has high economic and ecological value. In this study, microbial diversity and community structure in intestine, stomach, and mouth of paddlefish were detected using high-throughput sequencing. The results showed that the diversity and richness indices decreased along the digestive tract, and significantly lower proportion of those were observed in intestine. Firmicutes, Bacteroidetes and Proteobacteria were the dominant phyla. In top 10 phyla, there was no significant difference in mouth and stomach. But compared with intestine, there were significant differences in 8 of the 10 phyla, and Firmicutes and Bacteroidetes increased significantly, while Proteobacteria decreased significantly. There was no dominant genus in mouth and stomach, but Clostridium&#95;sensu&#95;stricto&#95;1 and uncultured&#95;bacterium&#95;o&#95;Bacteroidales was predominant in intestine. In conclusion, the species and abundance of microbiota in the mouth and stomach of paddlefish were mostly the same, but significantly different from those in intestine. Moreover, there was enrichment of the dominant bacteria in intestine., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Long et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Enzymatic degradation of algae cell wall carbohydrates by microorganisms is under increasing investigation as marine organic matter gains more value as a sustainable resource. The fate of carbon in the marine ecosystem is in part driven by these degradation processes. In this study, we observe the microbiome dynamics of the macroalga Fucus vesiculosus in 25-day-enrichment cultures resulting in partial degradation of the brown algae. Microbial community analyses revealed the phylum Pseudomonadota as the main bacterial fraction dominated by the genera Marinomonas and Vibrio. More importantly, a metagenome-based Hidden Markov model for specific glycosyl hydrolyses and sulphatases identified Bacteroidota as the phylum with the highest potential for cell wall degradation, contrary to their low abundance. For experimental verification, we cloned, expressed, and biochemically characterised two α-L-fucosidases, FUJM18 and FUJM20. While protein structure predictions suggest the highest similarity to a Bacillota origin, protein-protein blasts solely showed weak similarities to defined Bacteroidota proteins. Both enzymes were remarkably active at elevated temperatures and are the basis for a potential synthetic enzyme cocktail for large-scale algal destruction., (© 2024. The Author(s).)

Phocaeicola dorei and Phocaeicola vulgatus are very common and abundant members of the human gut microbiome and play an important role in the infant gut microbiome. These species are closely related and often confused for one another; yet, their genome comparison, interspecific diversity, and evolutionary relationships have not been studied in detail so far. Here, we perform phylogenetic analysis and comparative genomic analyses of these two Phocaeicola species. We report that P. dorei has a larger genome yet a smaller pan-genome than P. vulgatus. We found that this is likely because P. vulgatus is more plastic than P. dorei, with a larger repertoire of genetic mobile elements and fewer anti-phage defense systems. We also found that P. dorei directly descends from a clade of P. vulgatus¸ and experienced genome expansion through genetic drift and horizontal gene transfer. Overall, P. dorei and P. vulgatus have very different functional and carbohydrate utilisation profiles, hinting at different ecological strategies, yet they present similar antimicrobial resistance profiles., (© 2024. The Author(s).)

The Bacteroidota is one of the dominant bacterial phyla in corals. However, the exact taxa of those coral bacteria under the Bacteroidota are still unclear. Two aerobic, Gram-stain-negative, non-motile rods, designated strains BMA10 T and BMA12 T , were isolated from stony coral Porites lutea collected from Weizhou Island, PR China. Global alignment of 16S rRNA gene sequences indicated that both strains are closest to species of Fulvivirga with the highest identities being lower than 93 %, and the similarity value between these two strains was 92.3 %. Phylogenetic analysis based on 16S rRNA gene and genome sequences indicated that these two strains form an monophylogenetic lineage alongside the families Fulvivirgaceae , Reichenbachiellaceae , Roseivirgaceae , Marivirgaceae , Cyclobacteriaceae , and Cesiribacteraceae in the order Cytophagales , phylum Bacteroidota . The genomic DNA G+C contents of BMA10 T and BMA12 T were 38.4 and 41.9 mol%, respectively. The major polar lipids of BMA10 T were phosphatidylethanolamine, unidentified aminophospholipid, four unidentified aminolipids, and five unidentified lipids. While those of BMA12 T were phosphatidylethanolamine, two unidentified aminolipids, and five unidentified lipids. The major cellular fatty acids detected in both isolates were iso-C 15 : 0 and C 16 : 1  ω 5 c . Carbohydrate-active enzyme analysis indicated these two strains may utilize coral mucus or chitin. Based on above characteristics, these two strains are suggested to represent two new species in two new genera of a new family in the order Cytophagales , for which the name Splendidivirga corallicola gen. nov., sp. nov., Agaribacillus aureus gen. nov., sp. nov. and Splendidivirgaceae fam. nov. are proposed. The type strain of S. corallicola is BMA10 T (=MCCC 1K08300 T =KCTC 102045 T ), and that for A. aureus is BMA12 T (=MCCC 1K08309 T =KCTC 102046 T ).

Laminarin, a β(1,3)-glucan, serves as a storage polysaccharide in marine microalgae such as diatoms. Its abundance, water solubility and simple structure make it an appealing substrate for marine bacteria. Consequently, many marine bacteria have evolved strategies to scavenge and decompose laminarin, employing carbohydrate-binding modules (CBMs) as crucial components. In this study, we characterized two previously unassigned domains as laminarin-binding CBMs in multimodular proteins from the marine bacterium Christiangramia forsetii KT0803 T , thereby introducing the new laminarin-binding CBM families CBM102 and CBM103. We identified four CBM102s in a surface glycan-binding protein (SGBP) and a single CBM103 linked to a glycoside hydrolase module from family 16 (GH16&#95;3). Our analysis revealed that both modular proteins have an elongated shape, with GH16&#95;3 exhibiting greater flexibility than SGBP. This flexibility may aid in the recognition and/or degradation of laminarin, while the constraints in SGBP could facilitate the docking of laminarin onto the bacterial surface. Exploration of bacterial metagenome-assembled genomes (MAGs) from phytoplankton blooms in the North Sea showed that both laminarin-binding CBM families are widespread among marine Bacteroidota. The high protein abundance of CBM102- and CBM103-containing proteins during phytoplankton blooms further emphasizes their significance in marine laminarin utilization., (© 2024 The Authors. Environmental Microbiology published by John Wiley & Sons Ltd.)

A taxonomic investigation was conducted on four bacterial strains isolated from soil contaminated with polycyclic aromatic hydrocarbons and heavy metals. Phylogenetic analysis revealed that these strains belonged to the family Chitinophagaceae. Examination of the 16S rRNA genes indicated that their sequence identities were below 97.6 % compared to any known and validly nominated bacterial species. The genomes of the four strains ranged from 4.12 to 8.76 Mb, with overall G + C molar contents varying from 41.28 % to 50.39 %. Predominant cellular fatty acids included iso-C 15:0 , iso-C 15:1 G, and iso-C 17:0 3-OH. The average nucleotide identity ranged from 66.90 % to 74.63 %, and digital DNA-DNA hybridization was 12.5-12.8 %. Based on the genomic and phenotypic features of the new strains, four novel species and two new genera were proposed within the family Chitinophagaceae. The ecological distributions were investigated by data-mining of NCBI databases, and results showed that additional strains or species of the newly proposed taxa were widely distributed in various environments, including polluted soil and waters. Functional analysis demonstrated that strains H1-2-19X T , JS81 T , and JY13-12 T exhibited resistance to arsenite (III) and chromate (VI). The proposed names for the four novel species are Paraflavitalea pollutisoli (type strain H1-2-19X T  = JCM 36460 T  = CGMCC 1.61321 T ), Terrimonas pollutisoli (type strain H1YJ31 T  = JCM 36215 T  = CGMCC 1.61343 T ), Pollutibacter soli (type strain JS81 T  = JCM 36462 T  = CGMCC 1.61338 T ), and Polluticoccus soli (type strain JY13-12 T  = JCM 36463 T  = CGMCC 1.61341 T )., 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 GmbH. All rights reserved.)

Low pH (LpH) poses a significant challenge to the health, immune response, and growth of aquatic animals worldwide. Crayfish (Procambarus clarkii) is a globally farmed freshwater species with a remarkable adaptability to various environmental stressors. However, the effects of LpH stress on the microbiota and host metabolism in crayfish intestines remain poorly understood. In this study, integrated analyses of antioxidant enzyme activity, histopathological damage, 16S rRNA gene sequencing, and liquid chromatography-mass spectrometry (LC-MS) were performed to investigate the physiology, histopathology, microbiota, and metabolite changes in crayfish intestines exposed to LpH treatment. The results showed that LpH stress induced obvious changes in superoxide dismutase and catalase activities and histopathological alterations in crayfish intestines. Furthermore, 16S rRNA gene sequencing analysis revealed that exposure to LpH caused significant alterations in the diversity and composition of the crayfish intestinal microbiota at the phylum and genus levels. At the genus level, 14 genera including Bacilloplasma, Citrobacter, Shewanella, Vibrio, RsaHf231, Erysipelatoclostridium, Anaerorhabdus, Dysgonomonas, Flavobacterium, Tyzzerella, Brachymonas, Muribaculaceae, Propionivibrio, and Comamonas, exhibited significant differences in their relative abundances. The LC-MS analysis revealed 859 differentially expressed metabolites in crayfish intestines in response to LpH, including 363 and 496 upregulated and downregulated metabolites, respectively. These identified metabolites exhibited significant enrichment in 24 Kyoto Encyclopedia of Genes and Genomes pathways (p < 0.05), including seven and 17 upregulated and downregulated pathways, respectively. These pathways are mainly associated with energy and amino acid metabolism. Correlation analysis revealed a strong correlation between the metabolites and intestinal microbiota of crayfish during LpH treatment. These findings suggest that LpH may induce significant oxidative stress, intestinal tissue damage, disruption of intestinal microbiota homeostasis, and alterations in the metabolism in crayfish. These findings provide valuable insights into how the microbial and metabolic processes of crayfish intestines respond to LpH stress., 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.)

The pink-colored and strictly aerobic bacterium strain, designated as TK19036 T , was isolated from mesopelagic layer of the Southwest Indian Ocean. This novel isolate can grow at 10-45 °C (optimum, 30 °C), pH 6.0-8.0 (optimum, pH 7.0), and 2-14% NaCl concentrations (w/v) (optimum, 6%). The predominant respiratory quinone was Menaquinone-7. Major polar lipid profiles contained two aminolipids, aminophospholipid, two glycolipids, phosphatidylethanolamine, and three unknown polar lipids. The preponderant cellular fatty acids were iso-C 15:0 , C 16:1 ω5c and iso-C 17:0 3-OH. Phylogenetic analyses based on 16S rRNA gene sequence uncovered that the strain TK19036 T pertained to the family Catalinimonadaceae under phylum Bacteroidota, and formed a distinct lineage with the closed species Tunicatimonas pelagia NBRC 107804 T . The up-to-bacteria-core gene phylogenetic trees also demonstrated a deep and novel branch formed by the strain TK19036 T within the family Catalinimonadaceae. Based on chemotaxonomic, phylogenetic and genomic features presented above, strain TK19036 T represents a novel species from a novel genus of the family Catalinimonadaceae, for which the name Roseihalotalea indica gen. nov. sp. nov. is proposed. The type strain is TK19036 T (= CGMCC 1.18940 T  = NBRC 116371 T )., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

We explored the metabolic integration of Blattella germanica and its obligate endosymbiont Blattabacterium cuenoti by the transcriptomic analysis of the fat body of quasi-aposymbiotic cockroaches, where the endosymbionts were almost entirely removed with rifampicin. Fat bodies from quasi-aposymbiotic insects displayed large differences in gene expression compared to controls. In quasi-aposymbionts, the metabolism of phenylalanine and tyrosine involved in cuticle sclerotization and pigmentation increased drastically to compensate for the deficiency in the biosynthesis of these amino acids by the endosymbionts. On the other hand, the uricolytic pathway and the biosynthesis of uric acid were severely decreased, probably because the reduced population of endosymbionts was unable to metabolize urea to ammonia. Metabolite transporters that could be involved in the endosymbiosis process were identified. Immune system and antimicrobial peptide (AMP) gene expression was also reduced in quasi-aposymbionts, genes encoding peptidoglycan-recognition proteins, which may provide clues for the maintenance of the symbiotic relationship, as well as three AMP genes whose involvement in the symbiotic relationship will require additional analysis. Finally, a search for AMP-like factors that could be involved in controlling the endosymbiont identified two orphan genes encoding proteins smaller than 200 amino acids underexpressed in quasi-aposymbionts, suggesting a role in the host-endosymbiont relationship.

Ferriphaselus amnicola GF-20 is the first Fe-oxidizing bacterium isolated from the continental subsurface. It was isolated from groundwater circulating at 20 m depth in the fractured-rock catchment observatory of Guidel-Ploemeur (France). Strain GF-20 is a neutrophilic, iron- and thiosulfate-oxidizer and grows autotrophically. The strain shows a preference for low oxygen concentrations, which suggests an adaptation to the limiting oxygen conditions of the subsurface. It produces extracellular stalks and dreads when grown with Fe(II) but does not secrete any structure when grown with thiosulfate. Phylogenetic analyses and genome comparisons revealed that strain GF-20 is affiliated with the species F. amnicola and is strikingly similar to F. amnicola strain OYT1, which was isolated from a groundwater seep in Japan. Based on the phenotypic and phylogenetic characteristics, we propose that GF-20 represents a new strain within the species F. amnicola., (© The Author(s) 2024. Published by Oxford University Press on behalf of FEMS.)

Constipation is a widespread problem in paediatric practice, affecting almost 30% of children. One of the key causal factors of constipation may be disturbances in the homeostasis of the gastrointestinal microbiome. The aim of the study was to determine whether the oral and fecal microbiomes differ between children with and without constipation. A total of 91 children over three years of age were included in the study. Of these, 57 were qualified to a group with constipation, and 34 to a group without. The saliva and stool microbiomes were evaluated using 16S rRNA gene amplicon sequencing. Functional constipation was associated with characteristic bacterial taxa in the fecal microbiota. Statistically significant differences were found at the family level: Burkholderiaceae (q = 0.047), Christensenellaceae (q = 0.047), Chlostridiaceae (q = 0.047) were significantly less abundant in the constipation group, while the Tannerellaceae (q = 0.007) were more abundant. At the genus level, the significant differences were observed for rare genera, including Christensenellaceae r-7 (q = 2.88 × 10 -2 ), Fusicatenibacter (q = 2.88 × 10 -2 ), Parabacteroides (q = 1.63 × 10 -2 ), Romboutsia (q = 3.19 × 10 -2 ) and Subdoligranulum (q = 1.17 × 10 -2 ). All of them were less abundant in children with constipation. With the exception of significant taxonomic changes affecting only feces, no differences were found in the alpha and beta diversity of feces and saliva. Children with functional constipation demonstrated significant differences in the abundance of specific bacteria in the stool microbiome compared to healthy children. It is possible that the rare genera identified in our study which were less abundant in the constipated patients (Christensellaceae r-7, Fusicatenibacter, Parabacteroides, Romboutsia and Subdoligranulum) may play a role in protection against constipation. No significant differences were observed between the two groups with regard to the saliva microbiome., (© 2024. The Author(s).)

The present study was undertaken to profile and compare the cecal microbial communities in conventionally (CONV) grown and raised without antibiotics (RWA) broiler chickens. Three hundred chickens were collected from five CONV and five RWA chicken farms on days 10, 24, and 35 of age. Microbial genomic DNA was extracted from cecal contents, and the V4-V5 hypervariable regions of the 16S rRNA gene were amplified and sequenced. Analysis of 16S rRNA sequence data indicated significant differences in the cecal microbial diversity and composition between CONV and RWA chickens on days 10, 24, and 35 days of age. On days 10 and 24, CONV chickens had higher richness and diversity of the cecal microbiome relative to RWA chickens. However, on day 35, this pattern reversed such that RWA chickens had higher richness and diversity of the cecal microbiome than the CONV groups. On days 10 and 24, the microbiomes of both CONV and RWA chickens were dominated by members of the phylum Firmicutes. On day 35, while Firmicutes remained dominant in the RWA chickens, the microbiome of CONV chickens exhibited am abundance of Bacteroidetes. The cecal microbiome of CONV chickens was enriched with the genus Faecalibacterium, Pseudoflavonifractor, unclassified Clostridium&#95;IV, Bacteroides, Alistipes, and Butyricimonas, whereas the cecal microbiome of RWA chickens was enriched with genus Anaerofilum, Butyricicoccu, Clostridium&#95;XlVb and unclassified Lachnospiraceae. Overall, the cecal microbiome richness, diversity, and composition were greatly influenced by the management program applied in these farms. These findings provide a foundation for further research on tailoring feed formulation or developing a consortium to modify the gut microbiome composition of RWA chickens., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Kairmi et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

The role of the gut microbiota in energy metabolism of the host has been established, both in overweight/obesity, as well as in undernutrition/stunting. Dysbiosis of the gut microbiota may predispose to stunting. The aim of this study was to compare the gut microbiota composition of stunted Indonesian children and non-stunted children between 36 and 45 months from two sites on the East Nusa Tenggara (ENT) islands. Fecal samples were collected from 100 stunted children and 100 non-stunted children in Kupang and North Kodi. The gut microbiota composition was determined by sequencing amplicons of the V3-V4 region of the 16S rRNA gene. Moreover, fecal SCFA concentrations were analyzed. The microbiota composition was correlated to anthropometric parameters and fecal metabolites. The phyla Bacteroidetes (Bacteroidota; q = 0.014) and Cyanobacteria (q = 0.049) were significantly higher in stunted children. Three taxa at genus levels were consistently significantly higher in stunted children at both sampling sites, namely Lachnoclostridium, Faecalibacterium and Veillonella (q < 7 * 10-4). These and 9 other taxa positively correlated to the z-score length-for-age (zlen), while 11 taxa negatively correlated with zlen. Several taxa also correlated with sanitary parameters, some of which were also significantly different between the two groups. All three fecal SCFA concentrations (acetate, propionate and butyrate) and their total were lower in stunted children compared to non-stunted children, although not significant for butyrate, indicating lower energy-extraction by the gut microbiota. Also, since SCFA have been shown to be involved in gut barrier function, barrier integrity may be affected in the stunted children. It remains to be seen if the three taxa are involved in stunting, or are changed due to e.g. differences in diet, hygiene status, or other factors. The observed differences in this study do not agree with our previous observations in children on Java, Indonesia. There are differences in infrastructure facilities such as clean water and sanitation on ENT and Java, which may contribute to the differences observed. The role of the gut microbiota in stunting therefore requires more in depth studies. Trial registration: the trial was registered at ClinicalTrials.gov with identifier number NCT05119218., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Surono et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Plasmids are extrachromosomal genetic elements that often encode fitness-enhancing features. However, many bacteria carry "cryptic" plasmids that do not confer clear beneficial functions. We identified one such cryptic plasmid, pBI143, which is ubiquitous across industrialized gut microbiomes and is 14 times as numerous as crAssphage, currently established as the most abundant extrachromosomal genetic element in the human gut. The majority of mutations in pBI143 accumulate in specific positions across thousands of metagenomes, indicating strong purifying selection. pBI143 is monoclonal in most individuals, likely due to the priority effect of the version first acquired, often from one's mother. pBI143 can transfer between Bacteroidales, and although it does not appear to impact bacterial host fitness in vivo, it can transiently acquire additional genetic content. We identified important practical applications of pBI143, including its use in identifying human fecal contamination and its potential as an alternative approach to track human colonic inflammatory states., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Sodium alginate is one of the most abundant sustainable gum source for dietary fiber production. However, the preparation efficiencies of low viscosity soluble dietary fiber from sodium alginate remain low. Here, a novel alginate lyase gene (FsAly7) from Flammeovirga sp. was identified and high-level expressed in Pichia pastoris for low viscosity soluble dietary fiber production. The highest enzyme production of 3050 U mL -1 was achieved, which is by far the highest yield ever reported. FsAly7 was used for low viscosity soluble dietary fiber production from sodium alginate, and the highest degradation rate of 85.5 % was achieved under a high substrate content of 20 % (w/v). The molecular weight of obtained soluble dietary fiber converged to 10.75 kDa. FsAly7 catalyzed the cleavage of glycosidic bonds in alginate chains with formation of unsaturated non-reducing ends simultaneously in the degradation process, thus altered the chemical structures of hydrolysates. The soluble dietary fiber exhibited excellent properties, including low viscosity, high oil adsorption capacity activity (2.20 ± 0.03 g g -1 ) and high emulsifying activity (60.05 ± 2.96 mL/100 mL). This investigation may provide a novel alginate lyase catalyst as well as a solution for the efficient production of low viscosity soluble dietary fiber from sodium alginate., 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.)

Background: Urbanization has an ecological and evolutionary effect on urban microorganisms. Microorganisms are fundamental to ecosystem functions, such as global biogeochemical cycles, biodegradation and biotransformation of pollutants, and restoration and maintenance of ecosystems. Changes in microbial communities can disrupt these essential processes, leading to imbalances within ecosystems. Studying the impact of human activities on urban microbes is critical to protecting the environment, human health, and overall urban sustainability., Methods: In this study, bacterial communities in the sediments of an urban artificial river were profiled by sequencing the 16S rRNA V3-V4 region. The samples collected from the eastern side of the Jiusha River were designated as the JHE group and were marked by persistent urban sewage discharges. The samples collected on the western side of the Jiusha River were categorized as the JHW group for comparative analysis., Results: The calculated alpha diversity indices indicated that the bacterial community in the JHW group exhibited greater species diversity and evenness than that of the JHE group. Proteobacteria was the most dominant phylum between the two groups, followed by Bacteroidota. The relative abundance of Proteobacteria and Bacteroidota accumulated in the JHE group was higher than in the JHW group. Therefore, the estimated biomarkers in the JHE group were divided evenly between Proteobacteria and Bacteroidota, whereas the biomarkers in the JHW group mainly belonged to Proteobacteria. The Sulfuricurvum , MND1 , and Thiobacillus genus were the major contributors to differences between the two groups. In contrast to JHW, JHE exhibited higher enzyme abundances related to hydrolases, oxidoreductases, and transferases, along with a prevalence of pathways associated with carbohydrate, energy, and amino acid metabolisms. Our study highlights the impact of human-induced water pollution on microorganisms in urban environments., Competing Interests: Yishi Li and Xuchao Zhuang are employed by Focused Photonics (Hangzhou), Inc. Daoming Lou is employed by Hangzhou Urban Water Facilities and River Conservation Management Center., (© 2024 Li et al.)

Background: Chickens are one of the most widely farmed animals worldwide and play a crucial role in meat and egg production. Gut microbiota is essential for chickens' health, disease, growth, and egg production. However, native chickens such as Jianghan chickens have better meat and egg production quality than centralized chickens, their intestinal microbial diversity is richer, and the potential gut microbial resources may bring health benefits to the host., Results: The bacterial species composition in the gut microbiota of Jianghan chickens is similar to that of other chicken breeds, with Phocaeicola and Bacteroides being the most abundant bacterial genera. The LEfSe analysis revealed significant differences in species composition and functional profiles between samples from Jingzhou and the other three groups. Functional annotation indicated that the gut microbiota of Jianghan chickens were dominated by metabolic genes, with the highest number of genes related to carbohydrate metabolism. Several antibiotic resistance genes (ARGs) were found, and the composition of ARGs was similar to that of factory-farmed chickens, suggesting that antibiotics were widely present in the gut microbiota of Jianghan chickens. The resistance genes of Jianghan chickens are mainly carried by microorganisms of the Bacteroidota and Bacillota phylum. In addition, more than 829 isolates were selected from the microbiota of Jianghan chickens. Following three rounds of acid and bile tolerance experiments performed on all the isolated strains, it was determined that six strains of Pediococcus acidilactici exhibited consistent tolerance. Further experiments confirmed that three of these strains (A4, B9, and C2) held substantial probiotic potential, with P. acidilactici B9 displaying the highest probiotic potential., Conclusions: This study elucidates the composition of the intestinal microbiota and functional gene repertoire in Jianghan chickens. Despite the absence of antibiotic supplementation, the intestinal microbial community of Jianghan chickens still demonstrates a profile of antibiotic resistance genes similar to that of intensively reared chickens, suggesting resistance genes are prevalent in free-ranging poultry. Moreover, Jianghan and intensively reared chickens host major resistance genes differently, an aspect seldom explored between free-range and pastured chickens. Furthermore, among the 829 isolates, three strains of P. acidilatici exhibited strong probiotic potential. These findings provide insights into the unique gut microbiota of Jianghan chickens and highlight potential probiotic strains offering benefits to the host. Video Abstract., (© 2024. The Author(s).)

In this study, we investigated the characteristics of gut microbiome in the metabolically healthy obese (MHO) patients, and how they correlate with metabolic and inflammatory profiles. A total of 120 obese people without metabolic comorbidities were recruited, and their clinical phenotypes, metabolic and inflammatory parameters were analysed. The faecal microbial markers originating from bacterial cell and extracellular vesicle (EV) were profiled using 16S rDNA sequencing. The total study population could be classified into two distinct enterotypes (enterotype I: Prevotellaceae-predominant, enterotype II: Akkermansia/Bacteroides-predominant), based on their stool EV-derived microbiome profile. When comparing the metabolic and inflammatory profiles, subjects in enterotype I had higher levels of serum IL-1β [false discovery rate (FDR) q = 0.050] and had a lower level of microbial diversity than enterotype II (Wilcoxon rank-sum test p < 0.01). Subjects in enterotype I had relatively higher abundance of Bacteroidetes, Prevotellaceae and Prevotella-derived EVs, and lower abundance of Actinobacteria, Firmicutes, Proteobacteria, Akkermansia and Bacteroides-derived EVs (FDR q < 0.05). In conclusion, HMO patients can be categorised into two distinct enterotypes by the faecal EV-derived microbiome profile. The enterotyping may be associated with different metabolic and inflammatory profiles. Further studies are warranted to elucidate the long-term prognostic impact of EV-derived microbiome in the obese population., (© 2024. The Author(s).)

An obligately anaerobic, non-motile, Gram-stain-negative, and rod-shaped strain KGMB11183 T was isolated from the feces of healthy Koreans. The growth of strain KGMB11183 T occurred at 30-45 °C (optimum 37 °C), at pH 6-9 (optimum pH 7), and in the presence of 0-0.5% NaCl (optimum 0%). Strain KGMB11183 T showed 16S rRNA gene sequence similarities of 95.4% and 94.2% to the closest recognized species, Phocaeicola plebeius M12 T , and Phocaeicola faecicola AGMB03916 T . Phylogenetic analysis showed that strain KGMB11183 T is a member of the genus Phocaeiocla. The major end products of fermentation are acetic acid and isobutyric acid. The major cellular fatty acids (> 10%) of this isolate were C 18:1 cis 9, anteiso-C 15:0 , and summed feature 11 (iso-C 17:0 3-OH and/or C 18:2 DMA). The assembled draft genome sequences of strain KGMB11183 T consisted of 3,215,271 bp with a DNA G + C content of 41.4%. According to genomic analysis, strain KGMB11183 T has a number of genes that produce acetic acid. The genome of strain KGMB11183 T encoded the starch utilization system (Sus) operon, SusCDEF suggesting that strain uses many complex polysaccharides that cannot be digested by humans. Based on the physiological, chemotaxonomic, phenotypic, and phylogenetic data, strain KGMB11183 T is regarded a novel species of the genus Phocaeicola. The type strain is KGMB11183 T (= KCTC 25284 T  = JCM 35696 T )., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Background: Sepsis can cause immune dysregulation and multiple organ failure in patients and eventually lead to death. The gut microbiota has demonstrated its precise therapeutic potential in the treatment of various diseases. This study aimed to discuss the structural changes of the gut microbiota in patients with sepsis and to analyze the differences in the gut microbiota of patients with different prognoses., Methods: We conducted a multicenter study in which rectal swab specimens were collected on the first and third days of sepsis diagnosis. A total of 70 specimens were collected, and gut microbiota information was obtained by 16S rRNA analysis., Results: The relative abundance of Enterococcus decreased in rectal swab specimens during the first three days of diagnosis in patients with sepsis, while the relative abundance of inflammation-associated Bacillus species such as Escherichia coli, Enterobacteriaceae, and Bacteroidetes increased. By comparing the differences in the flora of the survival group and the death group, we found that the abundance of Veillonella and Ruminococcus in the death group showed an increasing trend (p < 0.05), while the abundance of Prevotella&#95;6 and Prevotella&#95;sp&#95;S4&#95;BM14 was increased in surviving patients (p < 0.05)., Conclusions: The Firmicutes/Bacteroidetes ratio, reflecting overall gut microbial composition, was significantly lower on day three of sepsis diagnosis. Changes in the abundance of specific gut microbiota may serve as prognostic markers in patients with sepsis., (© 2024. The Author(s).)

Efficient recognition and transportation of chitin oligosaccharides are crucial steps for the utilization of chitin by heterotrophic bacteria. In this study, we employed structural biological and biochemical approaches to investigate the substrate recognition and acquisition mechanism of a novel chitin-binding SusD-like protein, AqSusD, which is derived from the chitin utilization gene cluster of a marine Bacteroides strain (Aquimarina sp. SCSIO 21287). We resolved the crystal structures of the AqSusD apo-protein and its complex with chitin oligosaccharides. Our results revealed that some crucial residues (Gln67, Phe87, and Asp276) underwent significant conformational changes to form tighter substrate binding sites for ligand binding. Moreover, we identified the functions of key amino acid residues and discovered that π-π stacking and hydrogen bonding between AqSusD and the ligand played significant roles in recognition of the protein for chitin oligosaccharide binding. Based on our findings and previous investigations, we put forward a model for the mechanism of chitin oligosaccharide recognition, capture, and transport by AqSusD, in collaboration with the membrane protein AqSusC. Our study deepens the understanding of the molecular-level "selfish" use of polysaccharides such as chitin by Bacteroides., (© 2023 Federation of European Biochemical Societies.)

Background: It is unclear what the causal relationship is between the gut microbiota and sepsis. Therefore, we employed Mendelian randomization (MR) to determine whether a causal link exists between the two., Methods: This study used publicly available genome-wide association studies (GWAS) summary data of gut microbiota, sepsis, sepsis (critical care), and sepsis (28-day death in critical care) to perform a two-sample MR analysis. To ensure the robustness of the results, we also conducted a sensitivity analysis., Results: For sepsis susceptibility, inverse variance weighted (IVW) estimates revealed that Victivallales (OR = 0.86, 95% CI, 0.78-0.94, p = 0.0017) was protective against sepsis, while Lentisphaerae (OR = 0.89, 95% CI, 0.80-0.99), Gammaproteobacteria (OR = 1.37, 95% CI, 1.08-1.73), Clostridiaceae1 (OR = 1.21, 95% CI, 1.04-1.40), RuminococcaceaeUCG011 (OR = 1.10, 95% CI, 1.01-1.20), Dialister (OR = 0.85, 95% CI, 0.74-0.97), and Coprococcus2 (OR = 0.81, 95% CI, 0.69-0.94) presented a suggestive association with the development of sepsis (all p < 0.05). For sepsis (critical care), IVW estimates indicated that Lentisphaerae (OR = 0.70, 95% CI, 0.53-0.93), Victivallales (OR = 0.67, 95% CI, 0.50-0.91), Anaerostipes (OR = 0.49, 95% CI, 0.31-0.76), LachnospiraceaeUCG004 (OR = 0.51, 95% CI, 0.34-0.77), and Coprococcus1 (OR = 0.66, 95% CI, 0.44-0.99) showed a suggestive negative correlation with sepsis (critical care) (all p < 0.05). For sepsis (28-day death in critical care), IVW estimates suggested that four bacterial taxa had a normally significant negative correlation with the risk of sepsis-related death, including Victivallales (OR = 0.54, 95% CI, 0.30-0.95), Coprococcus2 (OR = 0.34, 95% CI, 0.14-0.83), Ruminiclostridium6 (OR = 0.43, 95% CI, 0.22-0.83), and Coprococcus1 (OR = 0.45, 95% CI, 0.21-0.97), while two bacterial taxa were normally significantly positively linked to the risk of sepsis-related death, namely, Mollicutes (OR = 2.03, 95% CI, 1.01-4.08) and Bacteroidales (OR = 2.65, 95% CI, 1.18-5.96) (all p < 0.05). The robustness of the above correlations was verified by additional sensitivity analyses., Conclusion: This MR research found that several gut microbiota taxa were causally linked to the risk of sepsis, sepsis in critical care, and sepsis-related 28-day mortality in critical care., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Shang, Zhang, Qian, Huang, Li, Liu and Chen.)