Non-redundant Genomes Research Articles

Comparative Genomics Reveal Distinct Environment Preference and Functional Adaptation Among Lineages of Gemmatimonadota

Bacteria in the phylum Gemmatimonadota are globally distributed and abundant in microbial communities of various environments, playing an important role in driving biogeochemical cycling on Earth. Although high diversities in taxonomic composition and metabolic capabilities have been reported, little is known about the environmental preferences and associated functional features that facilitate adaptation among different Gemmatimonadota lineages. This study systematically analyzed the relationships between the environments, taxonomy, and functions of Gemmatimonadota lineages, by using a comparative genomics approach based on 1356 Gemmatimonadota genomes (213 high-quality and non-redundant genomes) available in a public database (NCBI). The taxonomic analysis showed that the 99.5% of the genomes belong to the class Gemmatimonadetes, and the rest of the genomes belong to the class Glassbacteria. Functional profiling revealed clear environmental preference among different lineages of Gemmatimonadota, and a marine group and two non-marine groups were identified and tested to be significantly different in functional composition. Further annotation and statistical comparison revealed a large number of functional genes (e.g., amiE, coxS, yfbK) that were significantly enriched in genomes from the marine group, supporting enhanced capabilities in energy acquisition, genetic information regulation (e.g., DNA repair), electrolyte homeostasis, and growth rate control. These genomic features are important for their survival in the marine environment, which is oligotrophic, variable, and with high salinity. The findings enhanced our understanding of the metabolic processes and environmental adaptation of Gemmatimonadota, and further advanced the understanding of the interactions of microorganisms and their habitats.

New insights into the enteric methane production based on the archaeal genome atlas of ruminant gastrointestinal tract

IntroductionAs one of the important components of ruminant gastrointestinal tract (GIT) microbiome, archaea are involved in many biological processes, especially methanogenesis. In spite of being a well-recognised member of the mammalian gut microbiome, it remains poorly characterized, partly due to the lack of a unified reference genome catalog. ObjectivesThis study aimed to construct a unified genome atlas that captures the wider diversity in archaea and is thus more appropriate for functional and taxonomic exploration of ruminant GIT archaea. MethodsWe collected archaeal genomes from public sources and new data of this study. We performed phylogenetic and functional genomics analysis, prophage identification based on the genomes. Using collected genomes as a reference, we conducted metagenomic and metatranscriptomic analysis on rumen fluid samples from 18 dairy cows, and investigated the correlation between rumen archaeal communities and methane (CH4) production profiles. ResultsWe constructed the ruminant GIT archaeal genomes (RGAG) by compiling 405 strain-level (160 species) non-redundant archaeal genomes from more than 10 ruminant species. Investigating the functional heterogeneity and methanogenic structure within RGAG revealed that it possessed 1,124 (99.5%) unknown microbial biosynthetic gene clusters. A survey of RGAG-borne prophages identified 63 prophages with 122 host-beneficial genes and 18 auxiliary metabolic genes. The pipeline for both metagenomics and metatranscriptomics generated in the study revealed the roles of archaeal genomes under-assessed in general multi-omics analysis. The highly expressed genus Methanosphaera was negatively correlated with CH4 production at the RNA level. ConclusionA unified genome atlas of ruminant GIT archaea is constructed in the study. Our analyses revealed the advantages of metatranscriptomics over metagenomics in studying rumen archaeal communities and further demonstrated that the multifaceted functions of ruminant archaea remain undiscovered. Differences in rumen archaeal community structure among cattle with different CH4 production profiles may reflect the balance between rumen hydrogen production and methanogenesis. Our work provides a new resource for interrogating archaeal functions in the ruminant GIT and potential targets for future CH4 reduction.

Coassembly and binning of a twenty-year metagenomic time-series from Lake Mendota

The North Temperate Lakes Long-Term Ecological Research (NTL-LTER) program has been extensively used to improve understanding of how aquatic ecosystems respond to environmental stressors, climate fluctuations, and human activities. Here, we report on the metagenomes of samples collected between 2000 and 2019 from Lake Mendota, a freshwater eutrophic lake within the NTL-LTER site. We utilized the distributed metagenome assembler MetaHipMer to coassemble over 10 terabases (Tbp) of data from 471 individual Illumina-sequenced metagenomes. A total of 95,523,664 contigs were assembled and binned to generate 1,894 non-redundant metagenome-assembled genomes (MAGs) with ≥50% completeness and ≤10% contamination. Phylogenomic analysis revealed that the MAGs were nearly exclusively bacterial, dominated by Pseudomonadota (Proteobacteria, N = 623) and Bacteroidota (N = 321). Nine eukaryotic MAGs were identified by eukCC with six assigned to the phylum Chlorophyta. Additionally, 6,350 high-quality viral sequences were identified by geNomad with the majority classified in the phylum Uroviricota. This expansive coassembled metagenomic dataset provides an unprecedented foundation to advance understanding of microbial communities in freshwater ecosystems and explore temporal ecosystem dynamics.

Non-redundant metagenome-assembled genomes of activated sludge reactors at different disturbances and scales

Metagenome-assembled genomes (MAGs) are microbial genomes reconstructed from metagenomic data and can be assigned to known taxa or lead to uncovering novel ones. MAGs can provide insights into how microbes interact with the environment. Here, we performed genome-resolved metagenomics on sequencing data from four studies using sequencing batch reactors at microcosm (~25 mL) and mesocosm (~4 L) scales inoculated with sludge from full-scale wastewater treatment plants. These studies investigated how microbial communities in such plants respond to two environmental disturbances: the presence of toxic 3-chloroaniline and changes in organic loading rate. We report 839 non-redundant MAGs with at least 50% completeness and 10% contamination (MIMAG medium-quality criteria). From these, 399 are of putative high-quality, while sixty-seven meet the MIMAG high-quality criteria. MAGs in this catalogue represent the microbial communities in sixty-eight laboratory-scale reactors used for the disturbance experiments, and in the full-scale wastewater treatment plant which provided the source sludge. This dataset can aid meta-studies aimed at understanding the responses of microbial communities to disturbances, particularly as ecosystems confront rapid environmental changes.

A compendium of ruminant gastrointestinal phage genomes revealed a higher proportion of lytic phages than in any other environments

BackgroundRuminants are important livestock animals that have a unique digestive system comprising multiple stomach compartments. Despite significant progress in the study of microbiome in the gastrointestinal tract (GIT) sites of ruminants, we still lack an understanding of the viral community of ruminants. Here, we surveyed its viral ecology using 2333 samples from 10 sites along the GIT of 8 ruminant species.ResultsWe present the Unified Ruminant Phage Catalogue (URPC), a comprehensive survey of phages in the GITs of ruminants including 64,922 non-redundant phage genomes. We characterized the distributions of the phage genomes in different ruminants and GIT sites and found that most phages were organism-specific. We revealed that ~ 60% of the ruminant phages were lytic, which was the highest as compared with those in all other environments and certainly will facilitate their applications in microbial interventions. To further facilitate the future applications of the phages, we also constructed a comprehensive virus-bacteria/archaea interaction network and identified dozens of phages that may have lytic effects on methanogenic archaea.ConclusionsThe URPC dataset represents a useful resource for future microbial interventions to improve ruminant production and ecological environmental qualities. Phages have great potential for controlling pathogenic bacterial/archaeal species and reducing methane emissions. Our findings provide insights into the virome ecology research of the ruminant GIT and offer a starting point for future research on phage therapy in ruminants.CJAF8kS71Z3NBgTNJ_uZFeVideo

Tracking investigation of archaeal composition and methanogenesis function from parental to offspring pigs

Archaea play a crucial role in microbial systems, including driving biochemical reactions and affecting host health by producing methane through hydrogen. The study of swine gut archaea has a positive significance in reducing methane emissions and improving feed utilization efficiency. However, the development and functional changes of archaea in the pig intestines have been overlooked for a long time. In this study, 54 fecal samples were collected from 36 parental pigs (18 boars and 18 pregnant/lactating sows), and 108 fecal samples from 18 offspring pigs during lactation, nursery, growing, and finishing stages were tracked and collected for metagenomic sequencing. We obtained 14 archaeal non-redundant metagenome-assembled genomes (MAGs). These archaea were classified as Methanobacteriota and Thermoplasmatota at the phylum level, and Methanobrevibacter, Methanosphaera, MX-02, and UBA71 at the genus level, involving hydrogenotrophic, methylotrophic, and acetoclastic pathways. The hydrogenotrophic pathway dominated the methanogenesis function, and the vast majority of archaea participated in it. Dietary changes profoundly affected the archaeal composition and methanogenesis function in pigs. The abundance of hydrogen-producing bacteria in parental pigs fed high-fiber diets was higher than that in offspring pigs fed low-fiber diets. The methanogenesis function was positively correlated with fiber decomposition functions and negatively correlated with the starch decomposition function. Increased abundance of sulfate reductase and fumarate reductase, as well as decreased acetate/propionate ratio, indicated that the upregulation of alternative hydrogen uptake pathways competing with methanogens may be the reason for the reduced methanogenesis function. These findings contribute to providing information and direction in the pig industry for the development of strategies to reduce methane emissions, improve feed efficiency, and maintain intestinal health.

Impact of rumen microbiome on cattle carcass traits

Rumen microbes are crucial in the anaerobic fermentation of plant polysaccharides to produce volatile fatty acids. However, limited information exists about the specific microbial species and strains in the rumen that affect carcass traits, and it is unclear whether there is a relationship between rumen metabolic functions and these traits. This study investigated the relationship between the rumen microbiome and carcass traits in beef cattle using 16S rRNA amplicon and shotgun sequencing. Metagenomic sequencing was used to compare the rumen microbiome between high-carcass weight (HW) and low-carcass weight (LW) cattle, and high-marbling (HM) and low-marbling (LM) cattle. Prokaryotic communities in the rumen of HW vs. LW and HM vs. LM were separated using 16S rRNA amplicon sequencing. Notably, shotgun metagenomic sequencing revealed that HW cattle had more methane-producing bacteria and ciliate protozoa, suggesting higher methane emissions. Additionally, variations were observed in the abundances of certain glycoside hydrolases and polysaccharide lyases involved in the ruminal degradation of plant polysaccharides between HW and LW. From our metagenome dataset, 807 non-redundant metagenome-assembled genomes (MAGs) of medium to high quality were obtained. Among these, 309 and 113 MAGs were associated with carcass weight and marbling, respectively.

Genomic and functional diversity of cultivated Bifidobacterium from human gut microbiota

The genus Bifidobacterium widely exists in human gut and has been increasingly used as the adjuvant probiotics for the prevention and treatment of diseases. However, the functional differences of Bifidobacterium genomes from different regions of the world remain unclear. We here describe an extensive study on the genomic characteristics and function annotations of 1512 genomes (clustered to 849 non-redundant genomes) of Bifidobacterium cultured from human gut. The distribution of some carbohydrate-active enzymes varied among different Bifidobacterium species and continents. More than 36% of the genomes of B. pseudocatenulatum harbored biosynthetic gene clusters of lanthipeptide-class-iv. 99.76% of the cultivated genomes of Bifidobacterium harbored genes of bile salt hydrolase. Most genomes of B. adolescentis, and all genomes of B. dentium harbored genes involved in gamma-aminobutyric acid synthesis. B. longum subsp. infantis were characterized harboring most genes related to human milk oligosaccharide utilization. Significant differences between the distribution of antibiotic resistance genes among different species and continents revealed the importance to use antibiotics precisely in the clinical treatment. Phages infecting Bifidobacterium and horizontal gene transfers occurring in genomes of Bifidobacterium were dependent on species and region sources, and might help Bifidobacterium adapt to the environment. In addition, the distribution of Bifidobacterium in human gut was found varied from different regions of the world. This study represents a comprehensive view of characteristics and functions of genomes of cultivated Bifidobacterium from human gut, and enables clinical advances in the future.

A mixed blessing of influent leachate microbes in downstream biotreatment systems of a full-scale landfill leachate treatment plant

In landfill leachate treatment plants (LLTPs), the microbiome plays a pivotal role in the decomposition of organic compounds, reduction in nutrient levels, and elimination of toxins. However, the effects of microbes in landfill leachate influents on downstream treatment systems remain poorly understood. To address this knowledge gap, we collected 23 metagenomic and 12 metatranscriptomic samples from landfill leachate and activated sludge from various treatment units in a full-scale LLTP. We successfully recovered 1,152 non-redundant metagenome-assembled genomes (MAGs), encompassing a wide taxonomic range, including 48 phyla, 95 classes, 166 orders, 247 families, 238 genera, and 1,152 species. More diverse microbes were observed in the influent leachate than in the downstream biotreatment systems, among which, an unprecedented ∼30 % of microbes with transcriptional expression migrated from the influent to the biological treatment units. Network analysis revealed that 399 shared MAGs across the four units exhibited high node centrality and degree, thus supporting enhanced interactions and increased stability of microbial communities. Functional reconstruction and genome characterization of MAGs indicated that these shared MAGs possessed greater capabilities for carbon, nitrogen, sulfur, and arsenic metabolism compared to non-shared MAGs. We further identified a novel species of Zixibacteria in the leachate influent with discrete lineages from those in other environments that accounted for up to 17 % of the abundance of the shared microbial community and exhibited notable metabolic versatility. Meanwhile, we presented groundbreaking evidence of the involvement of Zixibacteria-encoded genes in the production of harmful gas emissions, such as N2O and H2S, at the transcriptional level, thus suggesting that influent microbes may pose safety risks to downstream treatment systems. In summary, this study revealed the complex impact of the influent microbiome on LLTP and emphasizes the need to consider these microbial characteristics when designing treatment technologies and strategies for landfill leachate management.

Depth-dependent microbial metagenomes sampled in the northeastern Indian Ocean

The northeastern Indian Ocean exhibits distinct hydrographic characteristics influenced by various local and remote forces. Variations in these driving factors may alter the physiochemical properties of seawater, such as dissolved oxygen levels, and affect the diversity and function of microbial communities. How the microbial communities change across water depths spanning a dissolved oxygen gradient has not been well understood. Here we employed both 16S rDNA amplicon and metagenomic sequencing approaches to study the microbial communities collected from different water depths along the E87 transect in the northeastern Indian Ocean. Samples were collected from the surface, Deep Chlorophyll Maximum (DCM), Oxygen Minimum Zone (OMZ), and bathypelagic layers. Proteobacteria were prevalent throughout the water columns, while Thermoproteota were found to be abundant in the aphotic layers. A total of 675 non-redundant metagenome-assembled genomes (MAGs) were constructed, spanning 21 bacterial and 5 archaeal phyla. The community structure and genomic information provided by this dataset offer valuable resources for the analysis of microbial biogeography and metabolism in the northeastern Indian Ocean.

Global biogeography and ecological implications of cobamide-producing prokaryotes.

Cobamides, a class of essential coenzymes synthesized only by a subset of prokaryotes, are model nutrients in microbial interaction studies and play significant roles in global ecosystems. Yet, their spatial patterns and functional roles remain poorly understood. Herein, we present an in-depth examination of cobamide-producing microorganisms, drawn from a comprehensive analysis of 2862 marine and 2979 soil metagenomic samples. A total of 1934 nonredundant metagenome-assembled genomes (MAGs) potentially capable of producing cobamides de novo were identified. The cobamide-producing MAGs are taxonomically diverse but habitat specific. They constituted only a fraction of all the recovered MAGs, with the majority of MAGs being potential cobamide users. By mapping the distribution of cobamide producers in marine and soil environments, distinct latitudinal gradients were observed: the marine environment showed peak abundance at the equator, whereas soil environments peaked at mid-latitudes. Importantly, significant and positive links between the abundance of cobamide producers and the diversity and functions of microbial communities were observed, as well as their promotional roles in essential biogeochemical cycles. These associations were more pronounced in marine samples than in soil samples, which suggests a heightened propensity for microorganisms to engage in cobamide sharing in fluid environments relative to the more spatially restricted soil environment. These findings shed light on the global patterns and potential ecological roles of cobamide-producing microorganisms in marine and soil ecosystems, enhancing our understanding of large-scale microbial interactions.

Recruitment of complete crAss-like phage genomes reveals their presence in chicken viromes, few human-specific phages, and lack of universal detection.

The order Crassvirales, which includes the prototypical crAssphage (p-crAssphage), is predominantly associated with humans, rendering it the most abundant and widely distributed group of DNA phages in the human gut. The reported human specificity and wide global distribution of p-crAssphage makes it a promising human fecal marker. However, the specificity for the human gut as well as the geographical distribution around the globe of other members of the order Crassvirales remains unknown. To determine this, a recruitment analysis using 91 complete, non-redundant genomes of crAss-like phages in human and animal viromes revealed that only 13 crAss-like phages among the 91 phages analyzed were highly specific to humans, and p-crAssphage was not in this group. Investigations to elucidate whether any characteristic of the phages was responsible for their prevalence in humans showed that the 13 human crAss-like phages do not share a core genome. Phylogenomic analysis placed them in three independent families, indicating that within the Crassvirales group, human specificity is likely not a feature of a common ancestor but rather was introduced on separate/independent occasions in their evolutionary history. The 13 human crAss-like phages showed variable geographical distribution across human metagenomes worldwide, with some being more prevalent in certain countries than in others, but none being universally identified. The varied geographical distribution and the absence of a phylogenetic relationship among the human crAss-like phages are attributed to the emergence and dissemination of their bacterial host, the symbiotic human strains of Bacteroides, across various human populations occupying diverse ecological niches worldwide.

First comparative genomics analysis of Corynebacterium auriscanis.

Corynebacterium auriscanis is a bacterial species frequently isolated from dogs with external otitis or dermatitis and a zoonotic pathogen transmitted by dog bite. It is considered an opportunistic pathogen, but its pathogenicity mechanisms are poorly studied. Comparative genomics can identify virulence and niche factors that could contribute to understanding its lifestyle. The objectives of this project was to compare genomes of C. auriscanis to identify genes related to its virulence and lifestyle. The genome of strain 32 was sequenced using Illumina HiSeq 2500 (Illumina, CA, USA) and assembled using Unicycler. The two other non-redundant genomes from the same species available in GenBank were included in the analysis. All genomes were annotated and checked for taxonomy, assembly quality, mobile elements, CRISPR-Cas systems, and virulence and antimicrobial resistance genes. The virulence genes in the three genomes were compared to the ones from other pathogens commonly isolated with C. auriscanis. The species has 42 virulence factors that can be classified as niche factors, due to the absence of true virulence factors found in primary pathogens. The gene rbpA could confer basal levels of resistance to rifampin. The absence of true virulence factors in the three genomes suggests C. auriscanis has an opportunistic pathogen lifestyle.

Metagenome-assembled genomes from mineral tundra soils in Rásttigáisá, northern Norway.

Microbial communities in tundra soils remain largely unknown despite their important roles in the cycling of greenhouse gases. Here, we report 59 non-redundant metagenome-assembled genomes (MAGs) recovered from mineral tundra soils in Rásttigáisá, northern Norway. The MAGs were obtained by clustering contigs according to tetranucleotide frequency and differential coverage and were manually curated to remove contigs with outlying GC content and/or mean coverage. Most MAGs were assigned to the bacterial phyla Candidatus Dormibacterota (n=12), Verrucomicrobiota (n=10), and Acidobacteriota (n=9). All archaeal MAGs (n=4) belong to the genus Candidatus Nitrosopolaris (phylum Thermoproteota). The 59 Rásttigáisá MAGs expand our knowledge of the diversity and ecological roles of tundra microbiomes.

Horizontal gene transfer in activated sludge enhances microbial antimicrobial resistance and virulence

Activated sludge (AS) plays a vital role in removing organic pollutants and nutrients from wastewater. However, the risks posed by horizontal gene transfer (HGT) between bacteria in AS are still unclear. Here, a total of 478 high-quality non-redundant metagenome-assembled genomes (MAGs) were obtained. >50 % and 5 % of MAGs were involved in at least one HGT and recent HGT, respectively. Most of the transfers (82.4 %) of antimicrobial resistance genes (ARGs) occurred among the classes of Alphaproteobacteria and Gammaproteobacteria. The bacteria involved in the transfers of virulence factor genes (VFGs) mainly include Alphaproteobacteria (42.3 %), Bacteroidia (19.2 %), and Gammaproteobacteria (11.5 %). Moreover, the number of ARGs and VFGs in the classes of Alphaproteobacteria and Gammaproteobacteria was higher than that in other bacteria (P < 0.001). Mobile genetic elements were important contributors to ARGs and VFGs in AS bacteria. These results have implications for the management of antimicrobial resistance and virulence in activated sludge microorganisms.

Inter-kingdom interactions and stability of methanogens revealed by machine-learning guided multi-omics analysis of industrial-scale biogas plants

Multi-omics analysis is a powerful tool for the detection and study of inter-kingdom interactions, such as those between bacterial and archaeal members of complex biogas-producing microbial communities. In the present study, the microbiomes of three industrial-scale biogas digesters, each fed with different substrates, were analysed using a machine-learning guided genome-centric metagenomics framework complemented with metatranscriptome data. This data permitted us to elucidate the relationship between abundant core methanogenic communities and their syntrophic bacterial partners. In total, we detected 297 high-quality, non-redundant metagenome-assembled genomes (nrMAGs). Moreover, the assembled 16 S rRNA gene profiles of these nrMAGs showed that the phylum Firmicutes possessed the highest copy number, while the representatives of the archaeal domain had the lowest. Further investigation of the three anaerobic microbial communities showed characteristic alterations over time but remained specific to each industrial-scale biogas plant. The relative abundance of various microorganisms as revealed by metagenome data was independent from corresponding metatranscriptome activity data. Archaea showed considerably higher activity than was expected from their abundance. We detected 51 nrMAGs that were present in all three biogas plant microbiomes with different abundances. The core microbiome correlated with the main chemical fermentation parameters, and no individual parameter emerged as a predominant shaper of community composition. Various interspecies H2/electron transfer mechanisms were assigned to hydrogenotrophic methanogens in the biogas plants that ran on agricultural biomass and wastewater. Analysis of metatranscriptome data revealed that methanogenesis pathways were the most active of all main metabolic pathways.

Epiphytic common core bacteria in the microbiomes of co-located green (Ulva), brown (Saccharina) and red (Grateloupia, Gelidium) macroalgae

BackgroundMacroalgal epiphytic microbial communities constitute a rich resource for novel enzymes and compounds, but studies so far largely focused on tag-based microbial diversity analyses or limited metagenome sequencing of single macroalgal species.ResultsWe sampled epiphytic bacteria from specimens of Ulva sp. (green algae), Saccharina sp. (brown algae), Grateloupia sp. and Gelidium sp. (both red algae) together with seawater and sediment controls from a coastal reef in Weihai, China, during all seasons. Using 16S rRNA amplicon sequencing, we identified 14 core genera (consistently present on all macroalgae), and 14 dominant genera (consistently present on three of the macroalgae). Core genera represented ~ 0.7% of all genera, yet accounted for on average 51.1% of the bacterial abundances. Plate cultivation from all samples yielded 5,527 strains (macroalgae: 4,426) representing 1,235 species (685 potentially novel). Sequencing of selected strains yielded 820 non-redundant draft genomes (506 potentially novel), and sequencing of 23 sampled metagenomes yielded 1,619 metagenome-assembled genomes (MAGs), representing further 1,183 non-redundant genomes. 230 isolates and 153 genomes were obtained from the 28 core/dominant genera. We analyzed the genomic potential of phycosphere bacteria to degrade algal polysaccharides and to produce bioactive secondary metabolites. We predicted 4,451 polysaccharide utilization loci (PULs) and 8,810 biosynthetic gene clusters (BGCs). These were particularly prevalent in core/dominant genera.ConclusionsOur metabolic annotations and analyses of MAGs and genomes provide new insights into novel species of phycosphere bacteria and their ecological niches for an improved understanding of the macroalgal phycosphere microbiome.DnRc39z963CYrL7RdN5UNdVideo

Diversity, distribution, and functional potentials of magroviruses from marine and brackish waters.

Marine group II (MGII) archaea (Ca. Poseidoniales) are among the most abundant microbes in global oceanic surface waters and play an important role in driving marine biogeochemical cycles. Magroviruses - the viruses of MGII archaea have been recently found to occur ubiquitously in surface ocean. However, their diversity, distribution, and potential ecological functions in coastal zones especially brackish waters are unknown. Here we obtained 234 non-redundant magroviral genomes from brackish surface waters by using homology searches for viral signature proteins highlighting the uncovered vast diversity of this novel viral group. Phylogenetic analysis based on these brackish magroviruses along with previously reported marine ones identified six taxonomic groups with close evolutionary connection to both haloviruses and the viruses of Marine Group I archaea. Magroviruses were present abundantly both in brackish and open ocean samples with some showing habitat specification and others having broad spectrums of distribution between different habitats. Genome annotation suggests they may be involved in regulating multiple metabolic pathways of MGII archaea. Our results uncover the previously overlooked diversity and ecological potentials of a major archaeal virial group in global ocean and brackish waters and shed light on the cryptic evolutionary history of archaeal viruses.

Defense systems are pervasive across chromosomally integrated mobile genetic elements and are inversely correlated to virulence and antimicrobial resistance.

Mobile genetic elements (MGEs) are key promoters of microbial evolution. These elements can be located extrachromosomally or integrated into the chromosome. Well-known examples of chromosomally integrated MGEs (ciMGEs) are integrative and conjugative/mobilizable elements (ICEs and IMEs), and most studies to date have focused on the biological mechanisms that shape their lifestyle. It is crucial to profile the diversity and understand their distribution across the microbial community, as the number of genome sequences increases exponentially. Herein, I scanned a collection of >20000 bacterial and archaeal non-redundant genomes and found over 13 000 ciMGEs across multiple phyla, representing a massive increase in the number of ciMGEs available in public databases (<1000). Although ICEs are the most important ciMGEs for the accretion of defense systems, virulence, and antimicrobial resistance (AMR) genes, IMEs outnumbered ICEs. Moreover, defense systems, AMR, and virulence genes were negatively correlated in both ICEs and IMEs. Multiple ciMGEs form heterogeneous communities and challenge inter-phylum barriers. Finally, I observed that the functional landscape of ICEs was populated by uncharacterized proteins. Altogether, this study provides a comprehensive catalog of nucleotide sequences and associated metadata for ciMGEs from 34 phyla across the bacterial and archaeal domains.

Recovery of metagenome-assembled microbial genomes from a full-scale biogas plant of food waste by pacific biosciences high-fidelity sequencing.

Anaerobic digestion (AD) is important in treating of food waste, and thousands of metagenome-assembled genomes (MAGs) have been constructed for the microbiome in AD. However, due to the limitations of the short-read sequencing and assembly technologies, most of these MAGs are grouped from hundreds of short contigs by binning algorithms, and the errors are easily introduced. In this study, we constructed a total of 60 non-redundant microbial genomes from 64.5 Gb of PacBio high-fidelity (HiFi) long reads, generated from the digestate samples of a full-scale biogas plant fed with food waste. Of the 60 microbial genomes, all genomes have at least one copy of rRNA operons (16S, 23S, and 5S rRNA), 54 have ≥18 types of standard tRNA genes, and 39 are circular complete genomes. In comparison with the published short-read derived MAGs for AD, we found 23 genomes with average nucleotide identity less than 95% to any known MAGs. Besides, our HiFi-derived genomes have much higher average contig N50 size, slightly higher average genome size and lower contamination. GTDB-Tk classification of these genomes revealed two genomes belonging to novel genus and four genomes belonging to novel species, since their 16S rRNA genes have identities lower than 95 and 97% to any known 16S rRNA genes, respectively. Microbial community analysis based on the these assembled genomes reveals the most predominant phylum was Thermotogae (70.5%), followed by Euryarchaeota (6.1%), and Bacteroidetes (4.7%), and the most predominant bacterial and archaeal genera were Defluviitoga (69.1%) and Methanothrix (5.4%), respectively. Analysis of the full-length 16S rRNA genes identified from the HiFi reads gave similar microbial compositions to that derived from the 60 assembled genomes. High-fidelity sequencing not only generated microbial genomes with obviously improved quality but also recovered a substantial portion of novel genomes missed in previous short-read based studies, and the novel genomes will deepen our understanding of the microbial composition in AD of food waste.