A standardized bacterial taxonomy based on genome phylogeny substantially revises the tree of life

Unexpected Microbial and Genetic Diversity in the Gut of Chinese Giant Salamander

The gut microbiome is crucial for animal health, yet the diversity of the critically endangered Chinese giant salamander's gut microbiota remains largely uncharacterized. In this study, we first conducted a comprehensive landscape survey of the gut microbiome of the Chinese giant salamander using 16S rRNA sequencing across a wide geographic range, identifying a distinct microbial cluster within its habitat. Subsequently, using shotgun metagenomes, we recovered 1518 metagenome-assembled genomes. Notably, 85% of the newly identified genomes could not be assigned to any known bacterial species, indicating a significant presence of novel taxa in Chinese giant salamander intestines. We observed substantial species-level variations in the gut microbiome across different age groups, with some novel species uniquely enriched in specific age populations. From the gut symbionts, we established a gene catalog comprising 3 278 107 non-redundant protein-coding genes, of which 7733 were annotated into recognized KEGG orthology groups. Additionally, we found that the gut microbiota of the Chinese giant salamander exhibits enhanced functional capacities explicitly in lipid metabolism and assimilatory sulfate reduction. Significant variations in the abundance of related enzyme-encoding genes across age groups suggest the unique roles of microbial metabolism in salamander health. By identifying microbial genomes and constructing an integrated gene catalog from metagenomic data, we significantly expand the resources available for research on the gut microbiome of the Chinese giant salamander, paving the way for further investigations into its ecological and health-related implications.

Modeling microbiome-trait associations with taxonomy-adaptive neural networks

The human microbiome, a complex ecosystem of microorganisms inhabiting the body, plays a critical role in human health. Investigating its association with host traits is essential for understanding its impact on various diseases. Although shotgun metagenomic sequencing technologies have produced vast amounts of microbiome data, analyzing such data is highly challenging due to its sparsity, noisiness, and high feature dimensionality. Here, we develop MIOSTONE, an accurate and interpretable neural network model for microbiome-disease association that simulates a real taxonomy by encoding the relationships among microbial features. The taxonomy-encoding architecture provides a natural bridge from variations in microbial taxa abundance to variations in traits, encompassing increasingly coarse scales from species to domains. MIOSTONE has the ability to determine whether taxa within the corresponding taxonomic group provide a better explanation in a data-driven manner. MIOSTONE serves as an effective predictive model, as it not only accurately predicts microbiome-trait associations across extensive simulated and real datasets but also offers interpretability for scientific discovery. Both attributes are crucial for facilitating in silico investigations into the biological mechanisms underlying such associations among microbial taxa. Video Abstract.

Isolation and cultivation of a novel freshwater magnetotactic coccus FCR-1 containing unchained magnetosomes

Magnetotactic bacteria are ubiquitous aquatic prokaryotes that have the ability to biomineralize magnetite (Fe3O4) and/or greigite (Fe3S4) nanoparticles called magnetosomes. Magnetotactic cocci belonging to the class "Ca. Magnetococcia" are most frequently identified in freshwater habitats, but remain uncultivated. Here, we report for the first time axenic cultivation of freshwater magnetotactic coccus FCR-1 isolated from Chichijima, Japan. Strain FCR-1 grows microaerophilically in a semi-solid gellan gum medium. We find that strain FCR-1 biomineralizes Fe3O4 nanoparticles, which are not chained, into a cell. Based on phylogenomic analysis, compared with strains of the class "Ca. Magnetococcia", strain FCR-1 represents a novel genus of candidate family "Ca. Magnetaquicoccaceae" within the class "Ca. Magnetococcia" and we tentatively name this novel genus "Ca. Magnetaquiglobus chichijimensis". Our isolate provides a promising tool for elucidating the functions of unchained magnetosomes, the global distribution of magnetotactic bacteria and the origin of magnetotaxis.

Diversification, niche adaptation, and evolution of a candidate phylum thriving in the deep Critical Zone

The deep subsurface soil microbiome encompasses a vast amount of understudied phylogenetic diversity and metabolic novelty, and the metabolic capabilities and ecological roles of these communities remain largely unknown. We observed a widespread and relatively abundant bacterial phylum (CSP1-3) in deep soils and evaluated its phylogeny, ecology, metabolism, and evolutionary history. Genome analysis indicated that members of CSP1-3 were actively replicating in situ and were widely involved in the carbon, nitrogen, and sulfur cycles. We identified potential adaptive traits of CSP1-3 members for the oligotrophic deep soil environments, including a mixotrophic lifestyle, flexible energy metabolisms, and conservation pathways. The ancestor of CSP1-3 likely originated in an aquatic environment, subsequently colonizing topsoil and, later, deep soil environments, with major CSP1-3 clades adapted to each of these distinct niches. The transition into the terrestrial environment was associated with genome expansion, including the horizontal acquisition of a range of genes for carbohydrate and energy metabolism and, in one lineage, high-affinity terminal oxidases to support a microaerophilic lifestyle. Our results highlight the ecology and genome evolution of microbes in the deep Critical Zone.

Anthropogenic imprint on riverine plasmidome diversity and proliferation of antibiotic resistance genes following pollution and urbanization

Plasmids are key determinants in microbial ecology and evolution, facilitating the dissemination of adaptive traits and antibiotic resistance genes (ARGs). Although the molecular mechanisms governing plasmid replication, maintenance, and transfer have been extensively studied, the specific impacts of urbanization-induced pollution on plasmid ecology, diversity, and associated ARGs in tropical regions remain underexplored. This study investigates these dynamics in a tropical aquatic ecosystem, providing novel insights into how pollution shapes plasmid composition and function. In contrast to the observed decrease in chromosomal diversity, we demonstrate that pollution associated with urbanization increases the diversity and taxonomic composition of plasmids within a bacterial community (plasmidome). We analyzed eighteen water and sediment metagenomes, capturing a gradient of pollution and ARG contamination along a tropical urban river. Plasmid and chromosomal diversity profiles were found to be anti-correlated. Plasmid species enrichment along the pollution gradient led to significant compositional differences in water samples, where differentially abundant species suggest plasmid maintenance within specific taxonomic classes. Additionally, the diversity and abundance of ARGs related to the plasmidome increased concomitantly with the intensity of fecal and chemical pollution. These findings highlight the critical need for targeted plasmidome studies to better understand plasmids' environmental spread, as their dynamics are independent of chromosomal patterns. This research is crucial for understanding the consequences of bacterial evolution, particularly in the context of environmental and public health.

Cultivation of anaerobic bacteria: Foundations and principles

A brief history of techniques in anaerobic microbiology are presented leading up to the incorporation of several improvements we have used over the years to improve our culture of anaerobic microorganisms of environmental, industrial and clinical importance. Two overriding aspects from our combined 90 years of experience here are: the better one's control of anaerobic conditions and gas phases, the better results are obtained; techniques can and should be targeted for individual microorganisms and accompanying experiments. Continued improvements in anaerobic microbiology are expected and encouraged for the future.

Benchmarking metagenomic binning tools on real datasets across sequencing platforms and binning modes

Metagenomic binning is a culture-free approach that facilitates the recovery of metagenome-assembled genomes by grouping genomic fragments. However, there remains a lack of a comprehensive benchmark to evaluate the performance of metagenomic binning tools across various combinations of data types and binning modes. In this study, we benchmark 13 metagenomic binning tools using short-read, long-read, and hybrid data under co-assembly, single-sample, and multi-sample binning, respectively. The benchmark results demonstrate that multi-sample binning exhibits optimal performance across short-read, long-read, and hybrid data. Moreover, multi-sample binning outperforms other binning modes in identifying potential antibiotic resistance gene hosts and near-complete strains containing potential biosynthetic gene clusters across diverse data types. This study also recommends three efficient binners across all data-binning combinations, as well as high-performance binners for each combination.

Adaptive adjustment of profile HMM significance thresholds improves functional and metabolic insights into microbial genomes

Motivation

Gene function annotation in microbial genomes and metagenomes is a fundamental in silico first step toward understanding metabolic potential and determinants of fitness. The Kyoto Encyclopedia of Genes and Genomes publishes a curated list of profile hidden Markov models to identify orthologous gene families (KOfams) with roles in metabolism. However, the computational tools that rely upon KOfams yield different annotations for the same set of genomes, leading to different downstream biological inferences.

Results

Here, we apply three open-source software tools that can annotate KOfams to genomes of phylogenetically diverse bacterial families from host-associated and free-living biomes. We use multiple computational approaches to benchmark these methods and investigate individual case studies where they differ. Our results show that despite their fundamental similarities, these methods have different annotation rates and quality. In particular, a method that adaptively tunes sequence similarity thresholds substantially improves sensitivity while maintaining high accuracy. We observe particularly large improvements for protein families with few reference sequences, or when annotating genomes from nonmodel organisms (such as gut-dwelling Lachnospiraceae). Our findings show that small improvements in annotation workflows can maximize the utility of existing databases and meaningfully improve in silico characterizations of microbial metabolism.

Availability and implementation

Anvi'o is available at https://anvio.org under the GNU GPL license. Scripts and workflow are available at https://github.com/pbradleylab/2023-anvio-comparison under the MIT license.

Environmental matrix and moisture influence soil microbial phenotypes in a simplified porous media incubation

Soil moisture and porosity regulate microbial metabolism by influencing factors, such as system chemistry, substrate availability, and soil connectivity. However, accurately representing the soil environment and establishing a tractable microbial community that limits confounding variables is difficult. Here, we use a reduced-complexity microbial consortium grown in a glass bead porous media amended with chitin to test the effects of moisture and a structural matrix on microbial phenotypes. Leveraging metagenomes, metatranscriptomes, metaproteomes, and metabolomes, we saw that our porous media system significantly altered microbial phenotypes compared with the liquid incubations, denoting the importance of incorporating pores and surfaces for understanding microbial phenotypes in soils. These phenotypic shifts were mainly driven by differences in expression of Streptomyces and Ensifer, which included a significant decrease in overall chitin degradation between porous media and liquid. Our findings suggest that the success of Ensifer in porous media is likely related to its ability to repurpose carbon via the glyoxylate shunt amidst a lack of chitin degradation byproducts while potentially using polyhydroxyalkanoate granules as a C source. We also identified traits expressed by Ensifer and others, including motility, stress resistance, and carbon conservation, that likely influence the metabolic profiles observed across treatments. Together, these results demonstrate that porous media incubations promote structure-induced microbial phenotypes and are likely a better proxy for soil conditions than liquid culture systems. Furthermore, they emphasize that microbial phenotypes encompass not only the multi-enzyme pathways involved in metabolism but also include the complex interactions with the environment and other community members.IMPORTANCESoil moisture and porosity are critical in shaping microbial metabolism. However, accurately representing the soil environment in tractable laboratory experiments remains a challenging frontier. Through our reduced complexity microbial consortium experiment in porous media, we reveal that predicting microbial metabolism from gene-based pathways alone often falls short of capturing the intricate phenotypes driven by cellular interactions. Our findings highlight that porosity and moisture significantly affect chitin decomposition, with environmental matrix (i.e., glass beads) shifting community metabolism towards stress tolerance, reduced resource acquisition, and increased carbon conservation, ultimately invoking unique microbial strategies not evident in liquid cultures. Moreover, we find evidence that changes in moisture relate to community shifts regarding motility, transporters, and biofilm formation, which likely influence chitin degradation. Ultimately, our incubations showcase how reduced complexity communities can be informative of microbial metabolism and present a useful alternative to liquid cultures for studying soil microbial phenotypes.

Insights into the phylogenetic and metabolic diversity of Planctomycetota in anaerobic digesters and the isolation of novel Thermoguttaceae species

Studying bacteria in anaerobic digestion (AD) is crucial for optimizing microbial processes. While abundant taxa are often studied, less abundant groups may harbour novel metabolic potential. This study fills the gap by focusing on the Planctomycetota phylum, known to encode diverse carbohydrate-active enzymes (CAZymes). Despite their common presence in diverse aerobic and anaerobic environments, their role in AD is relatively unexplored. We utilized both culture-dependent and culture-independent techniques to investigate the phylogenetic and metabolic diversity of Planctomycetota within AD reactors. Our findings revealed that among the diverse planctomycetotal operational taxonomic units present, only a few are prevalent and abundant community members. Planctomycetota share functional traits with e.g. Verrucomicrobiota exhibiting distinct CAZyme gene repertoires that indicates specialization in degrading algal polysaccharides and glycoproteins. To explore the planctomycetotal metabolic capabilities, we monitored their presence in algal-fed digesters. Additionally, we isolated a strain from mucin-based medium, revealing its genetic potential for a mixotrophic lifestyle. Based on the genomic analysis, we propose to introduce the Candidatus Luxemburgiella decessa gen. nov. sp. nov., belonging to the Thermoguttaceae family within the Pirellulales order of the Planctomycetia class. This study enhances our understanding of Planctomycetota in AD by highlighting their phylogenetic diversity and metabolic capabilities.

Chromosome-level genome assembly of Eimeria tenella at the single-oocyst level

BACKGROUND

Eimeria are obligate protozoan parasites, and more than 1,500 species have been reported. However, Eimeria genomes lag behind many other eukaryotes since obtaining many oocysts is difficult due to a lack of sustainable in vitro culture, highly repetitive sequences, and mixed species infections. To address this challenge, we used whole-genome amplification of a single oocyst followed by long-read sequencing and obtained a chromosome-level genome of Eimeria tenella.

RESULTS

The assembled genome was 52.13 Mb long, encompassing 15 chromosomes and 46.94% repeat sequences. In total, 7,296 protein-coding genes were predicted, exhibiting high completeness, with 92.00% single-copy BUSCO genes. To the best of our knowledge, this is the first chromosome-level assembly of E. tenella using a combination of single-oocyst whole-genome amplification and long-read sequencing. Comparative genomic and transcriptome analyses confirmed evolutionary relationship and supported estimates of divergence time of apicomplexan parasites and identified AP2 and Myb gene families that may play indispensable roles in regulating the growth and development of E. tenella.

CONCLUSION

This high-quality genome assembly and the established sequencing strategy provide valuable community resources for comparative genomic and evolutionary analyses of the Eimeria clade. Additionally, our study also provides a valuable resource for exploring the roles of AP2 and Myb transcription factor genes in regulating the development of Eimeria parasites.

The translocator protein 18 kDa (TSPO) ligand etifoxine in an animal model of anxiety: Line- and sex-dependent effects on emotionality, stress reactivity, spine density, oxytocin receptors, steroids, and microbiome composition

The treatment of stress-related disorders such as anxiety and depression is still challenging. One potential therapeutical option are neurosteroids. Their synthesis is promoted by ligands of the mitochondrial translocator protein 18 kDa (TSPO). We tested the TSPO ligand etifoxine (ETX) in a rat model of hyper-anxiety and depression-like behavior, i.e., in female and male HAB (high anxiety-related behavior) rats, as well as in respective low anxiety (LAB) and non-selected control (NAB) rats for behavioral, molecular, cellular, and physiological parameters. Daily acute i.p. treatment with ETX or vehicle over 5 or 9 days revealed that ETX was most effective in female HAB rats; it reduced anxiety levels (5 days) and OXT-R binding brain site-specifically (5 and 9 days), and increased spine density (5 days). The behavioral ETX effect exclusively found in female HABs was accompanied by increased 3β5α-THDOC levels, without any effect in female LABs and NABs and on other neurosteroids. In males of all breeding lines, ETX changed a total of 10 out of 23 brain steroids. Passive stress-coping during 10-min forced swimming was not affected by 9-day treatment with ETX, the resulting stress-induced plasma corticosterone levels were higher in ETX-treated NAB rats of both sexes compared with their VEH-treated groups. The fecal bacterial composition was similar but beta diversity differed between HABs and LABs and from NABs independent of sex; ETX treatment had no effect. Therefore, we propose considering the aspect of sex in treatment strategies for anxiety disorders. This is particularly important to establish better treatment regimens for women.

Metagenomic deciphers the mobility and bacterial hosts of antibiotic resistance genes under antibiotics and heavy metals co-selection pressures in constructed wetlands

Both antibiotics and heavy metals exert significant selection pressures on antibiotic-resistance genes (ARGs). This study aimed to investigate the co-selection effects of doxycycline (DC) and cadmium (Cd) on ARGs in constructed wetlands (CWs). The results demonstrated that under antibiotic and heavy metal co-selection pressures, single high concentration DC/Cd or double high, relative abundances of metagenomics assembled genomes all reached 55.1%; meanwhile, the average ratio of ARG-containing contigs located on chromosomes was 61.8% (ranging from 50.4% to 70.6%) suggesting a more stable inheritance of ARGs. Antibiotic and heavy metal co-selection in single high concentration DC/Cd or double high groups stimulate the enrichment of ARG host bacteria, which exhibited complex multiple-resistant patterns accompanied by a host-specific pattern. Additionally, the potential transfer abilities of ARGs mediated by plasmids and integrative and conjugative elements (ICEs) were enhanced under single high-concentration DC/Cd or double high stresses. Together, antibiotic and heavy metal co-selection pressures increased occurrence frequencies of ARGs, MGEs, and their combinations and altered structural communities of ARG host bacteria, increasing the risk of the spread of ARGs. This study was helpful in understanding the dissemination of ARGs and simultaneously preventing the spread of heavy metal-resistant bacteria and ARGs under antibiotic and heavy metal co-selection in small- and micro-wetlands.

An Evolutionary-Focused Review of the Holosporales (Alphaproteobacteria): Diversity, Host Interactions, and Taxonomic Re-ranking as Holosporineae Subord. Nov

The order Holosporales is a broad and ancient lineage of bacteria obligatorily associated with eukaryotic hosts, mostly protists. Significantly, this is similar to other evolutionary distinct bacterial lineages (e.g. Rickettsiales and Chlamydiae). Here, we provide a detailed and comprehensive account on the current knowledge on the Holosporales. First, acknowledging the up-to-date phylogenetic reconstructions and recent nomenclatural proposals, we reevaluate their taxonomy, thus re-ranking them as a suborder, i.e. Holosporineae, within the order Rhodospirillales. Then, we examine the phylogenetic diversity of the Holosporineae, presenting the 20 described genera and many yet undescribed sub-lineages, as well as the variety of the respective environments of provenance and hosts, which belong to several different eukaryotic supergroups. Noteworthy representatives of the Holosporineae are the infectious intranuclear Holospora, the host manipulator 'Caedimonas', and the farmed shrimp pathogen 'Candidatus Hepatobacter'. Next, we put these bacteria in the broad context of the whole Holosporineae, by comparing with the available data on the least studied representatives, including genome sequences. Accordingly, we reason on the most probable evolutionary trajectories for host interactions, host specificity, and emergence of potential pathogens in aquaculture and possibly humans, as well as on future research directions to investigate those many open points on the Holosporineae.

Perturbation of Pseudomonas aeruginosa peptidoglycan recycling by anti-folates and design of a dual-action inhibitor

Peptidoglycan (PG) is an important bacterial macromolecule that confers cell shape and structural integrity, and is a key antibiotic target. Its synthesis and turnover are carefully coordinated with other cellular processes and pathways. Despite established connections between the biosynthesis of PG and the outer membrane, or PG and DNA replication, links between PG and folate metabolism remain comparatively unexplored. Folate is an essential cofactor for bacterial growth and is required for the synthesis of many important metabolites. Here we show that inhibition of folate synthesis in the important Gram-negative pathogen Pseudomonas aeruginosa has downstream effects on PG metabolism and integrity that can manifest as the formation of a subpopulation of round cells that can undergo explosive lysis. Folate inhibitors potentiated β-lactams by perturbation of PG recycling, reducing expression of the AmpC β-lactamase. Supporting this mechanism, folate inhibitors also synergized with fosfomycin, an inhibitor of MurA, the first committed step in PG synthesis that can be bypassed by PG recycling. These insights led to the design of a dual-active inhibitor that overcomes NDM-1 metallo-β lactamase-mediated meropenem resistance and synergizes with the folate inhibitor, trimethoprim. We show that folate and PG metabolism are intimately connected, and targeting this connection can overcome antibiotic resistance in Gram-negative pathogens.

IMPORTANCE

To combat the alarming global increase in superbugs amid the simultaneous scarcity of new drugs, we can create synergistic combinations of currently available antibiotics or chimeric molecules with dual activities, to minimize resistance. Here we show that older anti-folate drugs synergize with specific cell wall biosynthesis inhibitors to kill the priority pathogen, Pseudomonas aeruginosa. Anti-folate drugs caused a dose-dependent loss of rod cell shape followed by explosive lysis, and synergized with β-lactams that target D,D-carboxypeptidases required to tailor the cell wall. Anti-folates impaired cell wall recycling and subsequent downstream expression of the chromosomally encoded β-lactamase, AmpC, which normally destroys β-lactam antibiotics. Building on the anti-folate-like scaffold of a metallo-β-lactamase inhibitor, we created a new molecule, MLLB-2201, that potentiates β-lactams and anti-folates and restores meropenem activity against metallo-β-lactamase-expressing Escherichia coli. These strategies are useful ways to tackle the ongoing rise in dangerous bacterial pathogens.

Description of Cytobacillus Mangrovibacter sp. nov., and Cytobacillus Spartinae sp. nov., Isolated from Mangrove Sediment

Two Gram-stain-positive, aerobic, rod-shaped, and motile strains FJAT-53684 T and FJAT-54145 T were isolated from the mangrove sediment. They optimally grew at pH 8.0 and could tolerate NaCl up to 5% (w/v). The optimum temperature for growth of strains FJAT-53684 T and FJAT-54145 T were 35 and 40 ºC, respectively. The 16S rRNA gene sequence similarity between FJAT-53684 T and FJAT-54145 T was 97.1%. Both strains showed the highest 16S rRNA gene sequence similarity to the Cytobacillus species. Menaquinone-7 was the only respiratory quinone present in both strains. The major fatty acids (≥ 10%) in strain FJAT-53684 T were iso-C14:0, anteiso-C15:0, iso-C15:0, and iso-C19:0, while strain FJAT-54145 T consist of iso-C14:0, iso-C15:0, iso-C19:0, iso-C16:0, and C16:1 ω7c alcohol. The polar lipids present in both strains were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, unidentified lipid, unidentified phospholipid, and phosphatidylinositol. Their average nucleotide identity and digital DNA-DNA hybridization values were below the threshold values (95% and 70%, respectively) for species delineation. Based on the above results, strains FJAT-53684 T and FJAT-54145 T represent two novel species of the genus Cytobacillus, for which the names Cytobacillus mangrovibacter sp. nov., and Cytobacillus spartinae sp. nov., are proposed. The type strains are FJAT-53684 T (= JCM 35618 T = GDMCC 1.3071 T), and FJAT-54145 T (= JCM 35621 T = GDMCC 1.3079 T).

Large diversity in the O-chain biosynthetic cluster within populations of Pelagibacterales

Genomic diversity in prokaryotic species is largely due to the existence of extensive pangenomes, allowing different gene complements to be drawn depending on the strain. Here, we have studied the diversity of the O-chain polysaccharide biosynthesis cluster (OBC) in marine bacteria of the Pelagibacterales order as a proxy to measure such genetic diversity in a single population. The study of single-amplified genomes (SAGs) from the whole order found a pattern similar to that of other well-studied microbes, such as the Enterobacteriales or Alteromonas, where distinct OBCs represent strains containing different gene pools. We found that most of the OBC sharing happened among individuals of the same clonal frame (>99% average nucleotide identity). Moreover, given the parsimonious way this cluster changes, the diversity of the OBCs can be extrapolated to the size of the population's pangenome. This assumes that different OBCs correspond to lineages containing unique flexible gene pools, as seen in the aforementioned microbes. Through long-read metagenomics, we could detect 380 different OBCs at a single Mediterranean sampling site. Within a single population (single species and sample) of the endemic Ia.3/VII (gMED) genomospecies, we identified 158 OBCs, of which 130 were unique. These findings suggest that the gene pool within a single population might be substantial (several thousands). While this figure is large, it aligns with the complexity of the dissolved organic matter that these organisms can potentially degrade.IMPORTANCEDifferent strains of the same bacterial species contain very different gene pools. This has been long known by epidemiologists. However, it is unknown what gene pool is present in a single set of environmental conditions, i.e., the same time and place in free-living bacteria. Here, we have leveraged information from SAGs to analyze the diversity of the gene cluster coding for the O-chain polysaccharide, a typical component of the flexible gene pool classically used as a tool to differentiate strains in clinical microbiology. It evolves at a similar rate to the rest of the genome and does not seem to be affected by an arms race with phages. One single species of Pelagibacteriales (gMED) revealed an astounding diversity in one sample studied by long-read metagenomics. Our results point to a large gene pool (local pangenome) present in a single population, which is critical to interpreting the biological meaning of the pangenome, i.e., it provides intrapopulation diversity rather than characterizing strains with different distribution in time and/or space.

Genomic divergence across the tree of life

Nucleotide sequence data are being harnessed to identify species, even in cases in which organisms themselves are neither in hand nor witnessed. But how genome-wide sequence divergence maps to species status is far from clear. While gene sequence divergence is commonly used to delineate bacterial species, its correspondence to established species boundaries has yet to be explored across eukaryotic taxa. Because the processes underlying gene flow differ fundamentally between prokaryotes and eukaryotes, these domains are likely to differ in the relationship between reproductive isolation and genome-wide sequence divergence. In prokaryotes, homologous recombination, the basis of gene flow, depends directly on the degree of genomic sequence divergence, whereas in sexually reproducing eukaryotes, reproductive incompatibility can stem from changes in very few genes. Guided by measures of genome-wide sequence divergence in bacteria, we gauge how genomic criteria correspond to species boundaries in eukaryotes. In recognized species of eukaryotes, levels of gene sequence divergence within species are typically very small, averaging <1% across protein-coding regions in most animals, plants, and fungi. There are even instances in which divergence between sister species is the same or less than that among conspecifics. In contrast, bacterial species, defined as populations exchanging homologous genes, show levels of divergence both within and between species that are considerably higher. Although no single threshold delineates species, eukaryotic populations with >1% genome-wide sequence divergence are likely separate species, whereas prokaryotic populations with 1% divergence are still able to recombine and thus can be considered the same species.

Pre-exposure to stress reduces loss of community and genetic diversity following severe environmental disturbance

Environmental stress caused by anthropogenic impacts is increasing worldwide. Understanding the ecological and evolutionary consequences for biodiversity will be crucial for our ability to respond effectively. Historical exposure to environmental stress is expected to select for resistant species, shifting community composition toward more stress-tolerant taxa. Concurrent with this species sorting process, genotypes within resistant taxa that have the highest relative fitness under severe stress are expected to increase in frequency, leading to evolutionary adaptation. However, empirical demonstrations of these dual ecological and evolutionary processes in natural communities are rare. Here, we provide evidence for simultaneous species sorting and evolutionary adaptation across multiple species within a natural freshwater bacterial community. Using a two-phase stressor experimental design (acidification pre-exposure followed by severe acidification) in aquatic mesocosms, we show that pre-exposed communities were more resistant than naive communities to taxonomic loss when faced with severe acid stress. However, after sustained severe acidification, taxonomic richness of both pre-exposed and naive communities eventually converged. All communities experiencing severe acidification became dominated by an acidophilic bacterium, Acidiphilium rubrum, but this species retained greater genetic diversity and followed distinct evolutionary trajectories in pre-exposed relative to naive communities. These patterns were shared across other acidophilic species, providing repeated evidence for the impact of pre-exposure on evolutionary outcomes despite the convergence of community profiles. Our results underscore the need to consider both ecological and evolutionary processes to accurately predict the responses of natural communities to environmental change.

Microbial ecosystems and ecological driving forces in the deepest ocean sediments

Systematic exploration of the hadal zone, Earth's deepest oceanic realm, has historically faced technical limitations. Here, we collected 1,648 sediment samples at 6-11 km in the Mariana Trench, Yap Trench, and Philippine Basin for the Mariana Trench Environment and Ecology Research (MEER) project. Metagenomic and 16S rRNA gene amplicon sequencing generated the 92-Tbp MEER dataset, comprising 7,564 species (89.4% unreported), indicating high taxonomic novelty. Unlike in reported environments, neutral drift played a minimal role, while homogeneous selection (HoS, 50.5%) and dispersal limitation (DL, 43.8%) emerged as dominant ecological drivers. HoS favored streamlined genomes with key functions for hadal adaptation, e.g., aromatic compound utilization (oligotrophic adaptation) and antioxidation (high-pressure adaptation). Conversely, DL promoted versatile metabolism with larger genomes. These findings indicated that environmental factors drive the high taxonomic novelty in the hadal zone, advancing our understanding of the ecological mechanisms governing microbial ecosystems in such an extreme oceanic environment.

Mutations in Gordonia amarae mycolic acid biosynthetic pathway confer resistance to Patescibacteria parasite Mycosynbacter amalyticus

The obligate necrotrophic parasite, Candidatus Mycosynbacter amalyticus, a member of the Patescibacteria has been isolated from wastewater. Subsequent efforts have been directed toward unravelling its biological lifecycle and attachment mechanism facilitating infection and subsequent lysis of its Actinobacterial host, Gordonia amarae. Here, using electron cryo-tomography (CryoET), we reveal the molecular anatomy of parasitic Mycosynbacter amalyticus cells, uncovering an unusual infection process. Through laboratory-based evolution experiments, we generated eleven slow-growing independent spontaneous Gordonia amarae resistant mutants. Mycolic acids (MA) are key components of the outer cellular envelope of G. amarae and other Actinobacteria, with MA being the physical attribute implicated in G. amarae associated wastewater foaming. CryoET and genome sequencing exposed absence of intact MA and an associated suite of mutations predominantly occurring within the pks13 and pptT genes of the MA biosynthetic pathway. Our findings suggest that MA structural integrity is critical for attachment of Ca. Mycosynbacter amalyticus to its host.

Novel arsenate-respiring bacteria drive arsenic biogeochemical cycling in Tibetan geothermal springs revealed by DNA-SIP based metagenomics

Arsenic (As) is a toxic element posing health risks globally, with geothermal environment as one of the hotspots. Arsenic biotransformation is mainly mediated by microorganisms which often employ diverse metabolic strategies for survival. However, the microorganisms responsible for As cycling and their survival strategies in geothermal environment in Tibet, the Third Pole, remain unclear. To address this knowledge gap, we investigated As biotransformation in representative geothermal springs using DNA-stable isotope probing (DNA-SIP) combined with metagenomic sequencing. As(V) reduction to the more toxic As(III) was found to be prevalent. Pseudomonas and Thermincola were identified as the dominant As(V)-reducing bacteria (AsRB). Metagenome-assembled genomes (MAGs) affiliated with AsRB contained abundant genes encoding As(V)-respiratory reductase (arrA, 1044.34 transcripts per million (TPM)), nitrate reduction pathway (e.g., narG), and Wood-Ljungdahl pathway (e.g., acsA), indicating their role as dissimilatory As(V)-reducing prokaryotes (DARPs) with diverse metabolic strategies. Here, Thermincola's potential of As(V) reduction via arrA and carbon fixation via Wood-Ljungdahl pathway was observed for the first time, which was found to be widespread in various ecosystems. Our study unravels the key players driving As biogeochemical cycle in Tibetan geothermal springs and provides insights into the genetic mechanisms enabling their survival in extreme environments.

NapBiome trial: Targeting gut microbiota to improve sleep rhythm and developmental and behavioural outcomes in early childhood in a birth cohort in Switzerland - a study protocol

INTRODUCTION

The gut-brain axis plays a crucial role in the regulation and development of psychological and physical processes. The first year of life is a critical period for the development of the gut microbiome, which parallels important milestones in establishing sleep rhythm and brain development. Growing evidence suggests that the gut microbiome influences sleep, cognition and early neurodevelopment. For term-born and preterm-born infants, difficulties in sleep regulation may have consequences on health. Identifying effective interventions on the gut-brain axis in early life is likely to have long-term implications for the health and development of at-risk infants.

METHODS AND ANALYSES

In this multicentre, four-group, double-blinded, placebo (PLC)-controlled randomised trial with a factorial design, 120 preterm-born and 260 term-born infants will be included. The study will investigate whether the administration of daily synbiotics or PLC for a duration of 3 months improves sleep patterns and neurodevelopmental outcomes up to 2 years of age. The trial will also: (1) determine the association between gut microbiota, sleep patterns and health outcomes in children up to 2 years of age; and (2) leverage the interactions between gut microbiota, brain and sleep to develop new intervention strategies for at-risk infants.

ETHICS AND DISSEMINATION

The NapBiome trial has received ethical approval by the Committee of Northwestern and Central Switzerland and Canton Vaud, Switzerland (#2024-01681). Outcomes will be disseminated through publication and will be presented at scientific conferences. Metagenomic data will be shared through the European Nucleotide Archive.

TRIAL REGISTRATION NUMBER

The US National Institutes of Health NCT06396689.

Paenibacillus campi sp. nov., a novel endophytic bacterium isolated from Pennisetum species

Two facultatively aerobic, Gram-stain-positive, rod-shaped, endospore-forming, endophytic bacteria, designated SGZ-1009T and SGZ-1014, were isolated from the plant Pennisetum sp. Strain SGZ-1009T grew at 5-50 °C, pH 4.5-11.0 and tolerated up to 4.5% NaCl (w/v), while strain SGZ-1014 exhibited growth at a temperature range of 10-50 °C, pH range 4.5-11.0 and tolerated up to 4.5% NaCl. Phylogenetic analysis based on 16S rRNA gene sequences indicated that these two strains belong to the genus Paenibacillus, closely related to the reference type strain of Paenibacillus wenxiniae DSM 100576T (similarity of 97.0%). The genomic relatedness values for both strains, SGZ-1009T and SGZ-1014, compared to their closest reference strain P. wenxiniae DSM 100576T, were 81.6% for average nucleotide identity and 26.0% for digital DNA-DNA hybridization, suggesting strain SGZ-1009T represents a novel species. The genomic DNA G+C content of strain SGZ-1009T was 46.4%. Both strains shared anteiso-C15:0 (55.9%) as the predominant fatty acid, menaquinone-7 as the major respiratory quinone and diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine as the major polar lipids. Based on these results, strains SGZ-1009T and SGZ-1014 represent a novel species of Paenibacillus, for which the name Paenibacillus campi sp. nov. is proposed. The type strain is SGZ-1009T (=MCCC 1K08892T=GDMCC 1.4280T=KCTC 43677T=JCM 36670T).

vClean: assessing virus sequence contamination in viral genomes

Recent advancements in viral metagenomics and single-virus genomics have improved our ability to obtain the draft genomes of environmental viruses. However, these methods can introduce virus sequence contaminations into viral genomes when short, fragmented partial sequences are present in the assembled contigs. These contaminations can lead to incorrect analyses; however, practical detection tools are lacking. In this study, we introduce vClean, a novel automated tool that detects contaminations in viral genomes. By applying machine learning to the nucleotide sequence features and gene patterns of the input viral genome, vClean could identify contaminations. Specifically, for tailed double-stranded DNA phages, we attempted accurate predictions by defining single-copy-like genes and counting their duplications. We evaluated the performance of vClean using simulated datasets derived from complete reference genomes, achieving a binary accuracy of 0.932. When vClean was applied to 4693 genomes of medium or higher quality derived from public ocean metagenomic data, 1604 genomes (34.2%) were identified as contaminated. We also demonstrated that vClean can detect contamination in single-virus genome data obtained from river water. vClean provides a new benchmark for quality control of environmental viral genomes and has the potential to become an essential tool for environmental viral genome analysis.

Conserved immunomodulation and variation in host association by Xanthomonadales commensals in Arabidopsis root microbiota

Suppression of chronic Arabidopsis immune responses is a widespread but typically strain-specific trait across the major bacterial lineages of the plant microbiota. We show by phylogenetic analysis and in planta associations with representative strains that immunomodulation is a highly conserved, ancestral trait across Xanthomonadales, and preceded specialization of some of these bacteria as host-adapted pathogens. Rhodanobacter R179 activates immune responses, yet root transcriptomics suggest this commensal evades host immune perception upon prolonged association. R179 camouflage likely results from combined activities of two transporter complexes (dssAB) and the selective elimination of immunogenic peptides derived from all partners. The ability of R179 to mask itself and other commensals from the plant immune system is consistent with a convergence of distinct root transcriptomes triggered by immunosuppressive or non-suppressive synthetic microbiota upon R179 co-inoculation. Immunomodulation through dssAB provided R179 with a competitive advantage in synthetic communities in the root compartment. We propose that extensive immunomodulation by Xanthomonadales is related to their adaptation to terrestrial habitats and might have contributed to variation in strain-specific root association, which together accounts for their prominent role in plant microbiota establishment.

Uncovering soil amendment-induced genomic and functional divergence in soybean rhizosphere microbiomes during cadmium-contaminated soil remediation: Novel insights from field multi-omics

Soil amendments exhibit great potential in reducing cadmium (Cd) bioavailability and its accumulation in crop grains, but their practical implications on microbial characteristics (genomic traits and ecological functions) remain unclear. The objective of this study was to combine metagenomics and metatranscriptomics to track the dynamics of bacterial and viral communities in the soybean rhizosphere during the remediation of Cd-contaminated soil using a commercial Mg-Ca-Si conditioner (CMC), applied at low and high (975 kg ha-1 and 1950 kg ha-1) rates under field conditions. Application of CMC increased the average size and decreased the guanine-cytosine (GC) content of microbial genomes, which were strongly shaped by soil pH and available Cd (ACd). Gene and transcript abundances analysis indicated that CMC promoted the enrichment of Alphaproteobacterial metagenome-assembled genomes (MAGs) carrying czcC gene encoding Cd efflux and dsbB gene encoding disulfide bond oxidoreductase. These genes are closely related to Cd resistance and exhibited notable (p < 0.05) increased expression in CMC-treated soils. Additionally, low and high CMC addition significantly increased viral alpha diversity by 5.7% and 9.6%, and viral activity by 3.3% and 7.8%, respectively, in comparison to the control. Temperate viruses were predicted as the major group (64%) and actively linked to the dominant host, and CMC amendment increased host metabolism and adaptability by enhancing (p < 0.05) the abundance and transcriptional activity of virus-encoded auxiliary metabolic genes (AMGs) involved in heavy metal resistance (ABC transport), sulfur cycling (cysH), and host metabolism (galE and queD) through "piggyback-the-winner" strategy. Structural equation modeling further revealed that CMC application influences Cd accumulation in soybean grains through its direct and indirect effects on soil properties and rhizosphere microbiomes, and highlighted the potential role of rhizosphere viruses in agricultural soil remediation.

Pseudomonads coordinate innate defense against viruses and bacteria with a single regulatory system

Bacterial cells live under the constant existential threats imposed by other bacteria and viruses. Their mechanisms for contending with these threats are well documented; however, the regulation of these diverse defense elements remains poorly understood. Here we show that bacteria can mount a genome-wide, coordinated, and highly effective immune response against bacterial and viral threats using a single regulatory pathway. Bioinformatic analyses revealed that Pseudomonas species broadly possess a specialized form of the Gac/Rsm regulatory pathway (GRP), which our prior work in Pseudomonas aeruginosa implicated in activating interbacterial antagonism defense mechanisms in response to neighbor cell death. Proteomic studies comparing GRP-activated and -inactivated strains derived from diverse Pseudomonas species showed that the pathway regulates a large and variable suite of factors implicated in defense against both bacterial and phage threats. Focusing on P. protegens, we identify profound phenotypic consequences of these factors against multiple forms of bacterial antagonism and several phage. Together, our results reveal that bacteria, like more complex organisms, couple danger sensing to the activation of an immune system with antibacterial and antiviral arms.

Paracoccus broussonetiae subsp. drimophilus subsp. nov., a Novel Subspecies Salt-Tolerant Endophytic Bacterium from Maize Root in Hunan

In an investigation exploring endophytic microbiota from agricultural crops, an aerobic, non-motile, Gram-negative, coccobacillus-shaped bacterial isolate, designated as strain NGMCC 1.201697T, was isolated from maize roots in Hunan Province, China. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain NGMCC 1.201697T belonged to the genus Paracoccus, showing the highest sequence similarity to Paracoccus broussonetiae CPCC 101403T (99.86%). The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) were 98.57% and 87.90% between the novel isolate and its closest phylogenetic relative. However, phenotypic characterization further differentiated the isolate from P. broussonetiae CPCC 101403T. The isolate showed enhanced environmental tolerance adaptability (growth in 0-8% NaCl and 4-37 °C), unique enzymatic activities (esterase C4, β-glucosidase, L-proline arylamidase, and β-galactosidase), and expanded metabolic capabilities (D-mannitol, D-cellobiose, saccharose, and so on). The major polar lipids consisted of diphosphatidylglycerol (DPG), phosphatidylethanolamine (PE), phosphatidylcholine (PC), phosphatidylglycerol (PG), two unidentified glycolipids (GLs) and four unidentified phospholipids (PLs). The predominant respiratory quinone was ubiquinone-10, and the major fatty acid was summed feature 8 (C18:1 ω7c, 69.42%). The DNA G + C content was 64.49 mol%. Based on results of these analyses, strain NGMCC 1.201697T represents a novel subspecies of Paracoccus broussonetiae, for which the name Paracoccus broussonetiae subsp. drimophilus subsp. nov. is proposed. The type-strain is NGMCC 1.201697T (=CGMCC 1.61958T =JCM 37104T).

Characterization of a second class Ie ribonucleotide reductase

Class I ribonucleotide reductases (RNRs) convert ribonucleotides into deoxyribonucleotides under oxic conditions. The R2 subunit provides a radical required for catalysis conducted by the R1 subunit. In most R2s the radical is generated on a tyrosine via oxidation by an adjacent metal site. The discovery of a metal-free R2 defined the new RNR subclass Ie. In R2e, three of the otherwise strictly conserved metal-binding glutamates in the active site are substituted. Two variants have been found, VPK and QSK. To date, the VPK version has been the focus of biochemical characterization. Here we characterize a QSK variant of R2e. We analyse the organismal distribution of the two R2e versions and find dozens of organisms relying solely on the QSK RNR for deoxyribonucleotide production. We demonstrate that the R2eQSK of the human pathogen Gardnerella vaginalis (Bifidobacterium vaginale) modifies the active site-adjacent tyrosine to DOPA. The amount of modified protein is shown to be dependent on coexpression with the other proteins encoded in the RNR operon. The DOPA containing R2eQSK can support ribonucleotide reduction in vitro while the unmodified protein cannot. Finally, we determined the first structures of R2eQSK in the unmodified and DOPA states.

Closed genomes of commercial inoculant rhizobia provide a blueprint for management of legume inoculation

Rhizobia are soil bacteria capable of establishing symbiosis within legume root nodules, where they reduce atmospheric N2 into ammonia and supply it to the plant for growth. Australian soils often lack rhizobia compatible with introduced agricultural legumes, so inoculation with exotic strains has become a common practice for over 50 years. While extensive research has assessed the N2-fixing capabilities of these inoculants, their genomics, taxonomy, and core and accessory gene phylogeny are poorly characterized. Furthermore, in some cases, inoculant strains have been developed from isolations made in Australia. It is unknown whether these strains represent naturalized exotic organisms, native rhizobia with a capacity to nodulate introduced legumes, or recombinant strains arising from horizontal transfer between introduced and native bacteria. Here, we describe the complete, closed genome sequences of 42 Australian commercial rhizobia. These strains span the genera, Bradyrhizobium, Mesorhizobium, Methylobacterium, Rhizobium, and Sinorhizobium, and only 23 strains were identified to species level. Within inoculant strain genomes, replicon structure and location of symbiosis genes were consistent with those of model strains for each genus, except for Rhizobium sp. SRDI969, where the symbiosis genes are chromosomally encoded. Genomic analysis of the strains isolated from Australia showed they were related to exotic strains, suggesting that they may have colonized Australian soils following undocumented introductions. These genome sequences provide the basis for accurate strain identification to manage inoculation and identify the prevalence and impact of horizontal gene transfer (HGT) on legume productivity.

IMPORTANCE

Inoculation of cultivated legumes with exotic rhizobia is integral to Australian agriculture in soils lacking compatible rhizobia. The Australian inoculant program supplies phenotypically characterized high-performing strains for farmers but in most cases, little is known about the genomes of these rhizobia. Horizontal gene transfer (HGT) of symbiosis genes from inoculant strains to native non-symbiotic rhizobia frequently occurs in Australian soils and can impact the long-term stability and efficacy of legume inoculation. Here, we present the analysis of reference-quality genomes for 42 Australian commercial rhizobial inoculants. We verify and classify the genetics, genome architecture, and taxonomy of these organisms. Importantly, these genome sequences will facilitate the accurate strain identification and monitoring of inoculants in soils and plant nodules, as well as enable detection of horizontal gene transfer to native rhizobia, thus ensuring the efficacy and integrity of Australia's legume inoculation program.

Genome-resolved adaptation strategies of Rhodobacterales to changing conditions in the Chesapeake and Delaware Bays

The abundant and metabolically versatile aquatic bacterial order, Rhodobacterales, influences marine biogeochemical cycles. We assessed Rhodobacterales metagenome-assembled genome (MAG) abundance, estimated growth rates, and potential and expressed functions in the Chesapeake and Delaware Bays, two important US estuaries. Phylogenomics of draft and draft/closed Rhodobacterales genomes from this study and others placed 46 nearly complete MAGs from these bays into 11 genera, many were not well characterized. Their abundances varied between the bays and were influenced by temperature, salinity, and silicate and phosphate concentrations. Rhodobacterales genera possessed unique and shared genes for transporters, photoheterotrophy, complex carbon degradation, nitrogen, and sulfur metabolism reflecting their seasonal differences in abundance and activity. Planktomarina genomospecies were more ubiquitous than the more niche specialists, HIMB11, CPC320, LFER01, and MED-G52. Their estimated growth rates were correlated to various factors including phosphate and silicate concentrations, cell density, and light. Metatranscriptomic analysis of four abundant genomospecies commonly revealed that aerobic anoxygenic photoheterotrophy-associated transcripts were highly abundant at night. These Rhodobacterales also differentially expressed genes for CO oxidation and nutrient transport and use between different environmental conditions. Phosphate concentrations and light penetration in the Chesapeake Bay likely contributed to higher estimated growth rates of HIMB11 and LFER01, respectively, in summer where they maintained higher ribosome concentrations and prevented physiological gene expression constraints by downregulating transporter genes compared to the Delaware Bay. Our study highlights the spatial and temporal shifts in estuarine Rhodobacterales within and between these bays reflected through their abundance, unique metabolisms, estimated growth rates, and activity changes.

IMPORTANCE

In the complex web of global biogeochemical nutrient cycling, the Rhodobacterales emerge as key players, exerting a profound influence through their abundance and dynamic activity. While previous studies have primarily investigated these organisms within marine ecosystems, this study delves into their roles within estuarine environments using a combination of metagenomic and metatranscriptomic analyses. We uncovered a range of Rhodobacterales genera, from generalists to specialists, each exhibiting distinct abundance patterns and gene expression profiles. This diversity equips them with the capacity to thrive amidst the varying environmental conditions encountered within dynamic estuarine habitats. Crucially, our findings illuminate the adaptable nature of estuarine Rhodobacterales, revealing their various energy production pathways and diverse resource management, especially during phytoplankton or algal blooms. Whether adopting a free-living or particle-attached existence, these organisms demonstrate remarkable flexibility in their metabolic strategies, underscoring their pivotal role in driving ecosystem dynamics within estuarine ecosystems.

Subspecies phylogeny in the human gut revealed by co-evolutionary constraints across the bacterial kingdom

The human gut microbiome contains many bacterial strains of the same species ("strain-level variants") that shape microbiome function. The tremendous scale and molecular resolution at which microbial communities are being interrogated motivates addressing how to describe strain-level variants. We introduce the "Spectral Tree"-an inferred tree of relatedness built from patterns of co-evolutionary constraint between greater than 7,000 diverse bacteria. Using the Spectral Tree to describe over 600 diverse gut commensal strains that we isolated, whole-genome sequenced, and metabolically profiled revealed (1) widespread phylogenetic structure among strain-level variants, (2) the origins of subspecies phylogeny as a shared history of phage infections across humans, and (3) the key role of inter-human strain variation in predicting strain-level metabolic qualities. Overall, our work demonstrates the existence and metabolic importance of structured phylogeny below the level of species for commensal gut bacteria, motivating a redefinition of individual strains according to their evolutionary context. A record of this paper's transparent peer review process is included in the supplemental information.

Shewanella is a putative producer of polyunsaturated fatty acids in the gut soil of the composting earthworm Eisenia fetida

Polyunsaturated fatty acids (PUFAs) play a crucial role in aiding bacteria to adapt to extreme and stressful environments. While there is a well-established understanding of their production, accrual, and transfer within marine ecosystems, knowledge about terrestrial environments remains limited. Investigation of the intestinal microbiome of earthworms has illuminated the presence of PUFAs presumably of microbial origin, which contrasts with the surrounding soil. To comprehensively study this phenomenon, a multi-faceted approach was employed, combining fatty acid analysis with amplicon sequencing of the PfaA-KS domain of the anaerobic fatty acid synthase gene (pfa), as well as the 16S rRNA and 18S rRNA genes. This methodology was applied to scrutinize the gut microbiome of Eisenia fetida, its compost-based dietary source, and the resultant castings. This study unveiled a distinct gut soil ecosystem from input compost and output castings in fatty acid profile as well as type and abundance of organisms. 16S sequencing provided insights into the microbial composition, showing increased relative abundance of certain Pseudomonadota, including Shewanellaceae, and Planctomycetota, including Gemmataceae within the gut microbiome compared to input bulk soil compost, while Actinomycetota and Bacillota were relatively enriched compared to the casted feces. Sequencing of the PfaA-KS domain revealed amplicon sequence variants (ASVs) belonging primarily to Shewanella. Intriguingly, the 20C PUFAs were identified only in gut soil samples, though PfaA-KS sequence abundance was highest in output castings, indicating a unique metabolism occurring only in the gut. Overall, the results indicate that Shewanella can explain PUFA enrichment in the gut environment because of the pfa gene presence detected via PfaA-KS sequence data.IMPORTANCEPrior research has demonstrated that earthworm microbiomes can potentially harbor polyunsaturated fatty acids (PUFAs) that are not found within their residing soil environment. Moreover, distinct indicator species have been pinpointed for various microbial genera in earthworm microbiomes. Nevertheless, none of these studies have integrated metataxonomic and fatty acid analyses to explore the origin of PUFA synthesis in any earthworm species, with the objective of identifying the specific organisms and locations responsible for this production. This study suggests that earthworms accumulate PUFAs produced from bacteria, especially Shewanella, activated through the gut ecosystem.

Targeted sequencing of Enterobacterales bacteria using CRISPR-Cas9 enrichment and Oxford Nanopore Technologies

Sequencing DNA directly from patient samples enables faster pathogen characterization compared to traditional culture-based approaches, but often yields insufficient sequence data for effective downstream analysis. CRISPR-Cas9 enrichment is designed to improve the yield of low abundance sequences but has not been thoroughly explored with Oxford Nanopore Technologies (ONT) for use in clinical bacterial epidemiology. We designed CRISPR-Cas9 guide RNAs to enrich the human pathogen Klebsiella pneumoniae, by targeting multi-locus sequence type (MLST) and transfer RNA (tRNA) genes, as well as common antimicrobial resistance (AMR) genes and the resistance-associated integron gene intI1. We validated enrichment performance in 20 K. pneumoniae isolates, finding that guides generated successful enrichment across all conserved sites except for one AMR gene in two isolates. Enrichment of MLST genes led to a correct allele call in all seven loci for 8 out of 10 isolates that had depth of 30× or more in these regions. We then compared enriched and unenriched sequencing of three human fecal samples spiked with K. pneumoniae at varying abundance. Enriched sequencing generated 56× and 11.3× the number of AMR and MLST reads, respectively, compared to unenriched sequencing, and required approximately one-third of the computational storage space. Targeting the intI1 gene often led to detection of 10-20 proximal resistance genes due to the long reads produced by ONT sequencing. We demonstrated that CRISPR-Cas9 enrichment combined with ONT sequencing enabled improved genomic characterization outcomes over unenriched sequencing of patient samples. This method could be used to inform infection control strategies by identifying patients colonized with high-risk strains.

IMPORTANCE

Understanding bacteria in complex samples can be challenging due to their low abundance, which often results in insufficient data for analysis. To improve the detection of harmful bacteria, we implemented a technique aimed at increasing the amount of data from target pathogens when combined with modern DNA sequencing technologies. Our technique uses CRISPR-Cas9 to target specific gene sequences in the bacterial pathogen Klebsiella pneumoniae and improve recovery from human stool samples. We found our enrichment method to significantly outperform traditional methods, generating far more data originating from our target genes. Additionally, we developed new computational techniques to further enhance the analysis, providing a thorough method for characterizing pathogens from complex biological samples.

Source-oriented risks of heavy metals and their effects on resistance genes in natural biofilms

Heavy metal (HM) introduction from various land-use patterns can be a major source of metal resistance genes (MRGs) entering river environments. This influx can trigger the occurrence of other resistomes, such as antibiotic resistance genes (ARGs), by improving co-resistant conjugative transfer. Biofilms, which form at water-solid interfaces, could serve as potential hotspots for HMs and resistance genes. However, the enrichment of HMs from various sources within biofilms and their effect on resistomes remain undocumented. This study aims to investigate the physicochemical properties of biofilm samples collected from the Heihui River, a tributary of the Lancang River, and to analyze the concentrations of nine HMs (As, Cd, Co, Cr, Cu, Ni, Pb, V, and Zn) within these biofilms. The 16S rRNA gene and metagenomic high-throughput sequencing techniques were integrated to uncover the association between HM accumulation levels in biofilms and ecological and health risks, considering the presence of two resistance genes. Natural sources (Co, Cr), industrial (As, Cu, V), agricultural (Cd, Ni), and transportation activities (Pb, Zn) markedly contributed to HM presence within biofilms, with industrial activities posing higher noncarcinogenic and carcinogenic risks than other sources. The network-correlation analyses revealed higher levels of ARG-MRG coexistence in biofilms, with the ecological and health risk index of HMs in biofilms closely associated with the abundance of both resistance genes. Furthermore, the biofilm As concentration markedly affected the abundance and expression of ARGs and MRGs, with elevated As levels within biofilms significantly and positively influencing all four functional categories of MRGs. Water pH also indirectly impacted these functional types by modulating the ionic form of HMs within the biofilm matrix. Our findings underscore the significance of integrating biofilms into environmental management practices and standards for assessing environmental quality.

Genome sequences of pathogenic and non-pathogenic Pantoea ananatis strains in maize (Zea mays L.)

We performed genome sequencing and comparative analysis of Pantoea ananatis strains isolated from corn leaves expressing typical bacterial leaf streak (BLS) and maize white spot (MWS) symptoms to confirm bacterial identity and to understand the relationship among these strains and P. ananatis strains isolated from different plant hosts in Brazil. In pathogenicity tests, strains 4.2 and 13.3 isolated from symptomatic BLS leaves were non-pathogenic on corn. In contrast, strain B13 isolated from MWS-diseased leaf tissue caused symptoms typical of MWS. Our comparative analysis revealed that all three strains are very genetically similar. The G+C (%) content of strains 4.2 and 13.3 was 53.5%, while the B13 content was 53.7%. Average nucleotide identity (ANI) analysis showed that strains B13 and 13.3, B13 and 4.2, and 4.2 and 13.3 shared ANIs of 99.17%, 99.15% and 99.99%, respectively. Strains 13.3, B13, and 4.2 shared ~99% ANI with P. ananatis type strain LMG 2665. To the best of our knowledge, these are the first genome sequences of P. ananatis strains isolated from corn in Brazil.

Virulence factor discovery identifies associations between the Fic gene family and Fap2+ fusobacteria in colorectal cancer microbiomes

Fusobacterium is a bacterium associated with colorectal cancer (CRC) tumorigenesis, progression, and metastasis. Fap2 is a fusobacteria-specific outer membrane galactose-binding lectin that mediates Fusobacterium adherence to and invasion of CRC tumors. Advances in omics analyses provide an opportunity to profile and identify microbial genomic features that correlate with the cancer-associated bacterial virulence factor Fap2. Here, we analyze genomes of Fusobacterium colon tumor isolates and find that a family of post-translational modification enzymes containing Fic domains is associated with Fap2 positivity in these strains. We demonstrate that Fic family genes expand with the presence of Fap2 in the fusobacterial pangenome. Through comparative genomic analysis, we find that Fap2+ Fusobacteriota are highly enriched with Fic gene families compared to other cancer-associated and human gut microbiome bacterial taxa. Using a global data set of CRC shotgun metagenomes, we show that fusobacterial Fic and Fap2 genes frequently co-occur in the fecal microbiomes of individuals with late-stage CRC. We further characterize specific Fic gene families harbored by Fap2+ Fusobacterium animalis genomes and detect recombination events and elements of horizontal gene transfer via synteny analysis of Fic gene loci. Exposure of a F. animalis strain to a colon adenocarcinoma cell line increases gene expression of fusobacterial Fic and virulence-associated adhesins. Finally, we demonstrate that Fic proteins are synthesized by F. animalis as Fic peptides are detectable in F. animalis monoculture supernatants. Taken together, our study uncovers Fic genes as potential virulence factors in Fap2+ fusobacterial genomes.IMPORTANCEAccumulating data support that bacterial members of the intra-tumoral microbiota critically influence colorectal cancer progression. Yet, relatively little is known about non-adhesin fusobacterial virulence factors that may influence carcinogenesis. Our genomic analysis and expression assays in fusobacteria identify Fic domain-containing genes, well-studied virulence factors in pathogenic bacteria, as potential fusobacterial virulence features. The Fic family proteins that we find are encoded by fusobacteria and expressed by Fusobacterium animalis merit future investigation to assess their roles in colorectal cancer development and progression.

Bacterial sensor evolved by decreasing complexity

Bacterial receptors feed into multiple signal transduction pathways that regulate a variety of cellular processes including gene expression, second messenger levels, and motility. Receptors are typically activated by signal binding to ligand-binding domains (LBDs). Cache domains are omnipresent LBDs found in bacteria, archaea, and eukaryotes, including humans. They form the predominant family of extracytosolic bacterial LBDs and were identified in all major receptor types. Cache domains are composed of either a single (sCache) or a double (dCache) structural module. The functional relevance of bimodular LBDs remains poorly understood. Here, we identify the PacF chemoreceptor in the phytopathogen Pectobacterium atrosepticum that recognizes formate at the membrane-distal module of its dCache domain, triggering chemoattraction. We further demonstrate that a family of formate-specific sCache domains has evolved from a dCache domain, exemplified by PacF, by losing the membrane-proximal module. By solving high-resolution structures of two family members in complex with formate, we show that the molecular basis for formate binding at sCache and dCache domains is highly similar, despite their low sequence identity. The apparent loss of the membrane-proximal module may be related to the observation that dCache domains bind ligands typically at the membrane-distal module, whereas studies have failed to find ligands bound in the membrane-proximal module. This work advances our understanding of signal sensing in bacterial receptors and suggests that evolution by reducing complexity may be a route for shaping diversity.

Isolation of Enterococcus hirae From Fresh White Yak Milk in Ledu District, Qinghai Province, China: A Comparative Genomic Analysis

Yak milk is a widely consumed dairy product rich in lactic acid bacteria. Although Enterococcus hirae (E. hirae) is commonly found in dairy products and other foods, there is limited information available on its genetic makeup in yak milk. In the present study, 10 E. hirae strains isolated and identified from fresh white yak milk samples, along with 442 E. hirae strains obtained from the NCBI database (totaling 452 strains), were subjected to comparative genomic analysis. The findings of this study revealed that E. hirae has an open pan-genomic structure that allows for its high adaptability and environmental plasticity. Notably, E. hirae isolates from fresh white yak milk had smaller genomes, encoded more functional genes, and had fewer copies of genes encoding carbohydrate-active enzymes involved in the degradation of oligosaccharide metabolism and autolysin synthesis (CE1, GH73, GH23, and GT4 families) than those from animal and human isolates (P < 0.05). Additionally, fresh white yak milk isolates carried only three intrinsic bacteriocins and lacked virulence factors, CRISPR-Cas systems, and resistance genes linked to pathogenicity, which may be attributed to their specialization in the milk-derived environment. This study provides new insights into the genetic and functional gene diversity of E. hirae and how it adapts to milk-derived habitats.

Representative Metagenomes of Mesophilic Biogas Reactor Across South Korea

Biogas production through the anaerobic digestion (AD) of organic waste plays a crucial role in promoting sustainability and closing the carbon cycle. Over the past decade, this has driven global research on biogas-producing microbiomes, leading to significant advances in our understanding of microbial diversity and metabolic pathways within AD plants. However, substantial knowledge gaps persist, particularly in understanding the specific microbial communities involved in biogas production in countries such as South Korea. The present dataset addresses one of these gaps by providing comprehensive information on the metagenomes of five full-scale mesophilic biogas reactors in South Korea. From 110 GB of raw DNA sequences, 401 metagenome-assembled genomes (MAGs) were created, which include 42,301 annotated genes. Of these, 187 MAGs (46.7%) were classified as high-quality based on Minimum Information about Metagenome-Assembled Genome (MIMAG) standards. The data presented here contribute to a broader understanding of biogas-specific microbial communities and offers a significant resource for future studies and advancements in sustainable biogas production.

Molecular Markers Specific for the Pseudomonadaceae Genera Provide Novel and Reliable Means for the Identification of Other Pseudomonas Strains/spp. Related to These Genera

Background/Objectives: Taxon-specific conserved signature indels (CSIs) exhibit a strong predictive ability of being found in other members of specific taxa/genera. Recently, multiple exclusively shared CSIs were identified for several newly described Pseudomonadaceae genera (viz. Aquipseudomonas, Atopomonas, Caenipseudomonas, Chryseomonas Ectopseudomonas, Geopseudomonas, Halopseudomonas, Metapseudomonas, Phytopseudomonas, Serpens, Stutzerimonas, Thiopseudomonas, and Zestomonas). This study examines the potential applications of these CSIs for identifying other Pseudomonas spp. (strains) related to these genera. Methods: This work utilized the AppIndels.com server, which uses information regarding the presence of known taxon-specific CSIs in a genome for predicting its taxonomic affiliation. For this purpose, sequence information for different CSIs specific for the Pseudomonadaceae species/genera were added to the server's database. Results: The AppIndels server was used to predict the taxonomic affiliation of 1972 genomes of unclassified Pseudomonas spp. (strains/isolates). Based upon finding a significant number of CSIs matching a specific taxon, the AppIndels server made positive predictions regarding the taxonomic affiliation of 299 examined genomes into the following clades/genera: Pseudomonas sensu stricto clade (46), Pseudomonas aeruginosa (64), Ectopseudomonas (46), Chryseomonas (32), Stutzerimonas (31), Metapseudomonas (22), Aquipseudomonas (21), Phytopseudomonas (17), Halopseudomonas (9), Geopseudomonas (4), Thiopseudomonas (3), Serpens (2), and Caenipseudomonas and Zestomonas (1 each). Phylogenetic studies confirmed that the taxonomic predictions by the server were 100% accurate. Conclusions: Our results demonstrate that the CSIs specific for Pseudomonadaceae species/genera, in conjunction with the AppIndels server, provides a novel and useful tool for identifying other species/strains affiliated with these species/genera. Phylogenetic studies suggest that many examined Pseudomonas strains constitute novel species in the indicated genera.

Roseicyclus amphidinii sp. nov., a novel bacterium isolated from the culture of a dinoflagellate Amphidinium carterae

A Gram-negative, rod-shaped and light pink-pigmented bacterial strain, designated Amp-Y-6T, was isolated from the culture of a dinoflagellate Amphidinium carterae CCMP1314. It can produce bacteriochlorophyll a. The 16S rRNA gene of strain Amp-Y-6T had the highest sequence similarity with Roseicyclus marinus CCMM001T of 98.1%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain Amp-Y-6T was affiliated to the genus Roseicyclus and formed a monophyletic clade with R. marinus CCMM001T and Roseicyclus mahoneyensis ML6T. The digital DNA-DNA hybridization, average nucleotide identity and average amino acid identity between strain Amp-Y-6T and the two phylogenetic relatives were 22.7-22.8, 80.4-80.5 and 79.5-80.2%, respectively. The respiratory quinone was Q-10. The major fatty acid composition was summed feature 8 (C18:1  ω7c and/or C18:1  ω6c). The draft genome size was 3.8 Mbp with a genomic G+C content of 68.1 mol%. Gene annotation showed that Amp-Y-6T contained a gene cluster responsible for the C-P degradation, indicating that it had the potential to provide a phosphate source for the dinoflagellate. Based on the phylogenetic, phenotypic and chemotaxonomic characteristics, strain Amp-Y-6T represents a novel species, for which the name Roseicyclus amphidinii sp. nov. is proposed. The type strain is Amp-Y-6T (=MCCC 1K08249T=KCTC 92882T).

Implication of Gut Mycobiome and Virome in Type-2 Diabetes Mellitus: Uncovering the Hidden Players

Type-2 diabetes mellitus (T2DM) is a global epidemic with significant societal costs. The gut microbiota, including its metabolites, plays a pivotal role in maintaining health, while gut dysbiosis is implicated in several metabolic disorders, including T2DM. Although data exists on the relationship between the gut bacteriome and metabolic disorders, further attention is needed for the mycobiome and virome. Recent advancements have begun to shed light on these connections, offering potential avenues for preventive measures. However, more comprehensive investigations are required to untangle the interrelations between different microbial kingdoms and their role in T2DM development or mitigation. This review presents a simplified overview of the alterations in the gut bacteriome in T2DM and delves into the current understanding of the mycobiome and virome's role in T2DM, along with their interactions with the cohabiting bacteriome. Subsequently, it explores into the age-related dynamics of the gut microbiome and the changes observed in the microbiome composition with the onset of T2DM. Further, we explore the basic workflow utilized in gut microbiome studies. Lastly, we discuss potential therapeutic interventions in gut microbiome research, which could contribute to the amelioration of the condition, serve as preventive measures, or pave the way towards personalized medicine.

Minisyncoccus archaeiphilus gen. nov., sp. nov., a mesophilic, obligate parasitic bacterium and proposal of Minisyncoccaceae fam. nov., Minisyncoccales ord. nov., Minisyncoccia class. nov. and Minisyncoccota phyl. nov. formerly referred to as Candidatus Patescibacteria or candidate phyla radiation

In the domain Bacteria, one of the largest, most diverse and environmentally ubiquitous phylogenetic groups, Candidatus Patescibacteria (also known as candidate phyla radiation/CPR), remains poorly characterized, leaving a major knowledge gap in microbial ecology. We recently discovered a novel cross-domain symbiosis between Ca. Patescibacteria and Archaea in highly purified enrichment cultures and proposed Candidatus taxa for the characterized species, including Ca. Minisyncoccus archaeophilus and the corresponding family Ca. Minisyncoccaceae. In this study, we report the isolation of this bacterium, designated strain PMX.108T, in a two-strain co-culture with a host archaeon, Methanospirillum hungatei strain DSM 864T (JF-1T), and hereby describe it as the first representative species of Ca. Patescibacteria. Strain PMX.108T was isolated from mesophilic methanogenic sludge in an anaerobic laboratory-scale bioreactor treating synthetic purified terephthalate- and dimethyl terephthalate-manufacturing wastewater. The strain could not grow axenically and is obligately anaerobic and parasitic, strictly depending on M. hungatei as a host. The genome was comparatively large (1.54 Mbp) compared to other members of the clade, lacked some genes involved in the biosynthesis pathway and encoded type IV pili-related genes associated with the parasitic lifestyle of ultrasmall microbes. The G+C content of the genomic DNA was 36.6 mol%. Here, we report the phenotypic and genomic properties of strain PMX.108T; we propose Minisyncoccus archaeiphilus gen. nov., sp. nov. to accommodate this strain. The type strain of the species is PMX.108T (=JCM 39522T). We also propose the associated family, order, class and phylum as Minisyncoccaceae fam. nov. Minisyncoccales nov., Minisyncoccia class. nov. and Minisyncoccota phyl. nov. within the bacterial kingdom Bacillati.

A decade of advances in human gut microbiome-derived biotherapeutics

Microbiome science has evolved rapidly in the past decade, with high-profile publications suggesting that the gut microbiome is a causal determinant of human health. This has led to the emergence of microbiome-focused biotechnology companies and pharmaceutical company investment in the research and development of gut-derived therapeutics. Despite the early promise of this field, the first generation of microbiome-derived therapeutics (faecal microbiota products) have only recently been approved for clinical use. Next-generation therapies based on readily culturable and as-yet-unculturable colonic bacterial species (with the latter estimated to comprise 63% of all detected species) have not yet progressed to pivotal phase 3 trials. This reflects the many challenges involved in developing a new class of drugs in an evolving field. Here we discuss the evolution of the live biotherapeutics field over the past decade, from the development of first-generation products to the emergence of rationally designed second- and third-generation live biotherapeutics. Finally, we present our outlook for the future of this field.

Metagenomic profiling of antibiotic resistance genes and their associations with the bacterial community along the Kanda River, an urban river in Japan

Antibiotic resistance genes (ARGs) present in urban rivers have the potential to disseminate antibiotic-resistant bacteria into other environments, posing significant threats to both ecological and public health. Although metagenomic analyses have been widely employed to detect ARGs in rivers, our understanding of their dynamics across different seasons in diverse watersheds remains limited. In this study, we performed a comprehensive genomic analysis of the Kanda River in Japan at 11 sites from upstream to estuary throughout the year to assess the spread of ARGs and their associations with bacterial communities. Analysis of 110 water samples using the 16S rRNA gene revealed variations in bacterial composition corresponding to seasonal changes in environmental parameters along the river. Shotgun metagenomics-based profiling of ARGs in 44 water samples indicated higher ARG abundance downstream, particularly during the summer. Weighted gene co-expression network analysis (WGCNA) linking bacterial lineages and ARGs revealed that 12 ARG subtypes co-occurred with 128 amplicon sequence variants (ASVs). WGCNA suggested potential hosts for ErmB, ErmF, ErmG, tetQ, tet (W/N/W), aadA2, and adeF, including gut-associated bacteria (e.g., Prevotella, Bacteroides, Arcobacter) and indigenous aquatic microbes (e.g., Limnohabitans and C39). In addition, Pseudarcobacter (a later synonym of Arcobater) was identified as a host for adeF, which was also confirmed by single cell genomics. This study shows that ARG distribution in urban rivers is affected by seasonal and geographical factors and demonstrates the importance of monitoring rivers using multiple types of genome sequencing, including 16S rRNA gene sequencing, metagenomics, and single cell genomics.

Oxidative adaptations in prokaryotes imply the oxygenic photosynthesis before crown-group Cyanobacteria

The metabolic transition from anaerobic to aerobic in prokaryotes reflects adaptations to oxidative stress. Methanogen, one of the earliest life forms on Earth, has evolved into three major groups within the Euryarchaeota, exhibiting different phylogenetic affiliations and metabolic characters. In comparison with other strictly anaerobic methanogenic groups, the Class II methanogens possess a better capability to adapt to limited oxygen pressure. Cyanobacteria is considered the first and only prokaryote evolving oxygenic photosynthesis and is responsible for the Great Oxidation Event on Earth. However, the connection between oxygenic Cyanobacteria and evolutionary adaptations to oxidative stress in prokaryotes remains elusive. Here, through the gene encoding structural maintenance of chromosomes (SMC) protein, which was horizontally transferred from ancient Class II methanogens to the last common ancestor of the crown-group Cyanobacteria, we demonstrate that the origin of extant Cyanobacteria was undoubtedly posterior to the occurrence of oxygen-tolerant Class II methanogens. In addition, we found that certain prokaryotic lineages had evolved the tolerance mechanisms against oxidative stress before the origin of extant Cyanobacteria. The contradiction that oxidative adaptations in Class II methanogens and other prokaryotes predating the crown-group oxygenic Cyanobacteria implies the existence of more ancient biological oxygenesis. We propose that these potential oxygenic organisms might represent the extinct phototrophs and first emerge during the Paleoarchean, contributing to the oxidative adaptations in the prokaryotic tree of life and facilitating the dispersal of reaction centers across the bacterial domain.

The Bacterial Genus Ramlibacter: Betaproteobacteria Capable of Surviving in Oligotrophic Environments Thanks to Several Shared Genetic Adaptation Traits

Ramlibacter tataouinensis, the type species of the genus Ramlibacter, is renowned for its ability to thrive in hot, arid and nutrient-poor desert soils. To investigate whether its adaptive properties are shared across all 20 currently described Ramlibacter species found in diverse terrestrial and aquatic habitats worldwide, we conducted a comprehensive analysis of 16S rRNA sequences and genomic information available from the literature. Our study encompassed approximately 40 deposited genomes, allowing us to propose a genomic phylogeny that aligns with the 16S rRNA phylogeny. Our findings reveal several conserved features across the genus Ramlibacter. This includes the presence of light sensors, environmental sensing networks, organic carbon and phosphate acquisition systems and the ability to store carbon and energy in the form of polyhydroxyalkanoate or polyphosphate granules. These shared traits rationalise the widespread distribution of Ramlibacter in oligotrophic terrestrial and aquatic environments. They also explain the genus' ability to withstand desiccation, endure extended periods of starvation, and survive in nutrient-depleted conditions. Notably, certain adaptive features are further enhanced in several species by their pleiomorphism and ability to form cysts. Overall, our study not only highlights the ecological adaptations of Ramlibacter species but also extends our understanding of microbial ecology in oligotrophic environments.

EasyMetagenome: A user-friendly and flexible pipeline for shotgun metagenomic analysis in microbiome research

Shotgun metagenomics has become a pivotal technology in microbiome research, enabling in-depth analysis of microbial communities at both the high-resolution taxonomic and functional levels. This approach provides valuable insights of microbial diversity, interactions, and their roles in health and disease. However, the complexity of data processing and the need for reproducibility pose significant challenges to researchers. To address these challenges, we developed EasyMetagenome, a user-friendly pipeline that supports multiple analysis methods, including quality control and host removal, read-based, assembly-based, and binning, along with advanced genome analysis. The pipeline also features customizable settings, comprehensive data visualizations, and detailed parameter explanations, ensuring its adaptability across a wide range of data scenarios. Looking forward, we aim to refine the pipeline by addressing host contamination issues, optimizing workflows for third-generation sequencing data, and integrating emerging technologies like deep learning and network analysis, to further enhance microbiome insights and data accuracy. EasyMetageonome is freely available at https://github.com/YongxinLiu/EasyMetagenome.