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PubMed2026

VicMAG, an open-source tool for visualizing circular metagenome-assembled genomes highlighting bacterial virulence and antimicrobial resistance.

Bacterial pathogens spread in clinical and environmental settings, and mobile genetic elements (MGEs), such as plasmids and phages, mediate the transfer of virulence factor genes (VFGs) and antimicrobial resistance genes (ARGs) among bacterial communities. Metagenomic analysis of environmental and wastewater samples using highly accurate long-read sequencing technologies, such as Pacific Biosciences (PacBio) HiFi sequencing, provides valuable insights into monitoring the regional spread of VFGs and ARGs, including dissemination mediated by MGEs. No visualization tool is currently available for the comprehensive display of numerous resulting circular metagenome-assembled genomes (cMAGs) with functional gene annotations. Here, we developed visualization of circular metagenome-assembled genome (VicMAG), a visualization tool for highly complex cMAGs derived from long-read metagenome assemblies annotated using updated databases of VFGs, ARGs, and MGEs. Using 353 cMAGs from PacBio HiFi sequencing of a wastewater sample, we demonstrated the utility of VicMAG for metagenome visualization. VicMAG provides comprehensive, size-aware visualization of cMAGs representing bacterial chromosomes and plasmids, annotated with VFGs, ARGs, and phages. By simultaneously visualizing all cMAGs in a framework, VicMAG facilitates a holistic understanding of the distribution and genomic context of VFGs and ARGs across complex microbial communities. This tool supports integrated surveillance of bacteria associated with virulence and antimicrobial resistance across clinical, environmental, and One Health contexts.

Metagenome↗

PubMed2026

Large-scale benchmarking of prokaryotic annotation tools across thousands of species.

BACKGROUND: Genome annotation is an important step in deriving functional meaning from prokaryotic sequencing data, yet systematic evaluations guiding tool selection are lacking. We present the first large-scale investigation of four prominent open-source annotation tools (Prokka, Bakta, EggNOG-mapper, and PGAP) across 156,033 diverse genomes. This includes Escherichia coli strains for baseline performance, thousands of archaea and bacteria genomes, as well as frameshifted and metagenome-assembled genomes. RESULTS: Bakta excels in annotating high-quality bacterial genomes, while PGAP was better for archaeal genomes and challenging bacterial assemblies, including metagenome-assembled, fragmented, or contaminated samples. For Gene Ontology annotation, PGAP consistently provides broader term coverage, whereas EggNOG-mapper offers more terms per feature. CONCLUSIONS: Our findings highlight tool-specific strengths crucial for selecting optimal solutions based on genome quality, taxonomy, and origin (e.g. MAGs). This study provides an evidence-based guide for users and informs future tool development.

Molecular Sequence Annotation↗

PubMed2026

Genome-resolved analysis reveals disruption of gut microbial vitamin B and K2 biosynthesis during Toxoplasma gondii infection in mice.

UNLABELLED: Toxoplasma gondii infection remodels the gut microbiome, yet its impact on microbial vitamin biosynthetic potential and host redox metabolism remains unclear. Here, we integrated mouse gut metagenomes with publicly available metagenome-assembled genomes (MAGs) to construct a genome-resolved atlas of B-vitamin and vitamin K2 biosynthesis. From 45,697 MAGs, we curated 4,771 representative genomes, of which 2,682 met high-quality criteria (completeness ≥90%, contamination <5%). Functional annotation identified 229,717 vitamin-related genes corresponding to 177 Kyoto Encyclopedia of Genes and Genomes (KEGG) orthologs across de novo pathways for eight B vitamins, thiamine (B1), riboflavin (B2), niacin (B3), pantothenate (B5), pyridoxine (B6), biotin (B7), folate (B9), cobalamin (B12), and vitamin K2. Among the high-quality genomes, 1,665 encoded complete de novo pathways for at least one vitamin, highlighting functional specialization and community-level complementarity. Transcripts per million-normalized metagenomic read counts revealed significant differences in KEGG ortholog abundances across six of the nine vitamin pathways. Reanalysis of metagenomic data from infected mice (acute, chronic, and control; n = 10 per group) revealed a stage-dependent reduction in α-diversity of vitamin biosynthesis pathways during acute infection, and a clear β-diversity separation from chronic and control groups. Core niacin biosynthesis genes (nadB, nadA, nadC) displayed phylum-specific redistribution, indicating selective remodeling of microbial NAD+ precursor production under infection-induced metabolic stress. These results suggest that T. gondii infection disrupts cooperative vitamin biosynthetic networks while specifically modulating niacin pathways linked to host NAD+ metabolism. IMPORTANCE: Gut microbes can synthesize essential vitamins, but how infection alters this function is poorly understood. By integrating mouse gut metagenomes with genome-resolved microbial data, we show that Toxoplasma gondii infection reshapes the vitamin biosynthetic potential of the gut microbiome in a stage-dependent manner. Acute infection reduces the diversity of vitamin biosynthesis pathways and shifts the taxonomic distribution of key niacin biosynthesis genes involved in microbial NAD+ precursor production. These findings identify vitamin metabolism, especially niacin-related pathways, as a sensitive functional axis of microbiome remodeling during infection. Our work links microbial taxonomic changes to functional metabolic consequences and suggests that microbiome-mediated regulation of NAD+-related metabolism may contribute to host redox adaptation during T. gondii infection.

B vitamins↗

PubMed2026

The global potential of freshwater microbes for plastic degradation.

Plastic pollution is becoming increasingly severe on a global scale, and the potential for biodegradation as a treatment method that is environmentally friendly merits greater attention. A significant number of genes that associated the degradation of plastic (PDAGs) have been identified, however, the distribution of these genes among microorganisms in global inland waters remains to be elucidated. A global-scale meta-analysis was conducted, incorporating approximately 1000 metagenome datasets of inland waters across seven continents. A total of 13,109 metagenome-assembled genomes (MAGs) were obtained by means of metagenomics binning, and 22,621 PDAGs were identified from these. Among these recognized PDAGs, phenylacetaldehyde dehydrogenase (PAD) was the most dominant (n = 16,664), followed by catalase (n = 5931). The predominant hosts for PAD and catalase were identified as Gamma-proteobacteria and Bacteroidia, respectively. The largest number of both PAD and catalase was found in MAGs from North America, while the average gene number in single MAG was highest in MAGs from Oceania. In accordance with the prediction of traits, PDAG-carrying MAGs from Europe demonstrated the fastest growth rate and the lowest optimal growth rate. Furthermore, 25 styrene monooxygenase (StyA) enzymes were identified, which were found to cluster into two distinct groups hosted by Alpha-proteobacteria and Gamma-proteobacteria, respectively. Moreover, 11 MAGs were observed to possess the complete pathway of polystyrene degradation. These results explored the potential of inland water microorganisms as a biological resource for plastic degradation and provided valuable microbial reference information that can be used to develop biological treatment technologies for mitigating plastics.

Plastics↗

PubMed2026

Genome-resolved assessment of archaeal diversity in full-scale anaerobic digesters reveals variability in mcrA primer coverage.

AIMS: Methanogenic archaea are key players in anaerobic digestion, driving methane production in biogas reactors. This study aimed to assess the diversity of methanogenic archaea in full-scale anaerobic digesters using genome-resolved metagenomics and to systematically evaluate the taxonomic coverage of commonly used mcrA-targeted qPCR primer sets against this genomic framework. METHODS AND RESULTS: Methanogenic diversity was assessed using 113 dereplicated archaeal metagenome-assembled genomes (MAGs) recovered from 109 full-scale anaerobic digesters treating diverse substrates. Genome-resolved analyses revealed a diverse archaeal community spanning multiple phyla, dominated by Halobacteriota and Methanobacteriota, with additional representatives from Methanobacteriota_B, Thermoplasmatota, and Thermoproteota. The presence of the mcrA gene was identified in a subset 55 MAGs, which were subsequently used as the genomic framework to evaluate six commonly used mcrA qPCR primer sets in silico. This subset clustered into nine phylogenetic groups and formed the basis for the primer coverage analysis. The evaluation revealed marked differences in taxonomic coverage among primer sets. Most primers preferentially detected Methanobacteriales and Methanosarcinales, while underrepresenting or excluding other methanogenic lineages, including H₂-dependent methylotrophic Methanomassiliicoccaceae. CONCLUSIONS: Commonly used mcrA primer sets differ substantially in their ability to capture methanogenic diversity, with some showing broad representation of reactor-associated methanogens and others exhibiting strong lineage-specific biases. Genome-resolved metagenomics provides an effective framework for benchmarking primer performance and supports the selection and improvement of molecular tools for more accurate monitoring of anaerobic digestion systems.

Archaea↗

PubMed2026

Metabolic niche differentiation and napA evolution stabilize partial denitrification in wastewater ecosystems.

Although partial denitrification (PD) is increasingly applied as a nitrite-supplying strategy for anammox-based nitrogen removal, the ecological distribution, metabolic specialization, and genomic determinants of stable nitrite accumulation remain poorly understood at the ecosystem scale. Here, we reconstructed 516 high-quality metagenome-assembled genomes (MAGs) using high-depth metagenomic sequencing of 107 wastewater treatment plants and classified denitrifiers according to their nitrite production or consumption capacities. Of these genomes, 23% (120 MAGs) were classified as partial denitrifiers, 41% (211 MAGs) as complete denitrifiers, and 36% (185 MAGs) as nitrite-reducing denitrifiers, revealing pronounced functional partitioning rather than dominance by complete denitrification pathways. Comparative genomics showed that partial denitrifiers possess metabolic architectures favoring rapid carbon oxidation and NADH generation while exhibiting constrained NADPH production and biosynthetic investment, thereby promoting nitrate-to-nitrite conversion but limiting subsequent nitrite reduction. Nitrite accumulation does not result from incomplete denitrification pathways but from metabolic niche differentiation. These metabolic trade-offs were further associated with the evolutionary divergence of the periplasmic nitrate reductase gene, napA, which displayed distinct sequence characteristics and genomic contexts between partial and complete denitrifiers. Integration of carbohydrate-active enzyme repertoires further revealed metabolic complementarity between partial denitrifiers and anammox bacteria, supporting efficient carbon handoff without direct substrate competition. From an engineering perspective, operating conditions that impose moderate electron limitation, such as low or fluctuating C/N ratios and intermittent carbon feeding, may selectively enrich partial denitrifiers and enhance a stable nitrite supply for PD-anammox systems. Together, these findings identify PD as a predictable ecological state shaped by genome-encoded metabolic specialization and provide a mechanistic basis for designing robust, low-carbon nitrogen-removal processes.

Anammox↗

PubMed2026

Ecological Restoration of the Soil-Like Function in the Bauxite Residue: Natural Microbiomes Mediated Molecular Transformation of Dissolved Organic Matter.

Soilization of bauxite residues offers a scalable route for long-term carbon management and ecological restoration. However, the microbial processes that transform exogenous organic inputs into stable soil-like carbon pools remain poorly resolved. Here, we combined cross-ecosystem meta-analysis, machine-learning prediction, native synthetic community (SynCom) construction, 13C-labeled straw microcosms, field validation, Fourier transform ion cyclotron resonance mass spectrometry, and genome-resolved metagenomics to unravel microbiome-mediated carbon transformation at the dissolved organic matter (DOM) molecular scale. Our meta-analysis revealed that alkaline industrial wastes retained soil-like DOM signatures but were enriched in microbial humic- and protein-like components, indicating active yet incomplete carbon processing. Guided by these patterns, native SynCom inoculation increased 13C incorporation into total organic carbon (TOC) and dissolved organic carbon (DOC), enlarged biodegradable and adsorbable DOC fractions, and shifted DOM from recalcitrant aromatic pools toward oxygenated carbohydrate-, tannin-, and phenolic-like molecular classes. Genome-resolved analyses linked this transformation to complementary polymer degradation and nutrient-cycling functions across fungal and bacterial guilds, including enriched carbohydrate-active enzymes in straw-carbon-utilizing metagenome-assembled genomes. Null model and thermodynamic analyses further showed that microbial communities were constrained by homogeneous selection, whereas DOM molecules were diversified through variable selection and redox-dependent transformation. Field-scale validation confirmed that SynCom promoted TOC and DOC accumulation and humic-like, high-density DOM fractions under alkaline conditions. Together, these findings establish a mechanistic framework in which functional microbiomes couple plant carbon depolymerization, DOM molecular diversification, and mineral-interactive carbon stabilization, providing a microbiome-guided strategy for carbon sequestration and soilization in the bauxite residue.

Soil↗

PubMed2026

Antimony species-dependent enrichment and transcriptional activity of antibiotic and metal resistance genes in the gut microbiome of male mice.

The gut microbiome is a reservoir for antibiotic resistance genes (ARGs) and is sensitive to environmental pollutants. ARGs in environmental and host-associated microbiomes can be enriched by metal(loid)s through co-selection with metal resistance genes (MRGs). However, as a ubiquitous toxic metalloid, antimony (Sb) induced alterations of ARGs in the gut microbiome and the underlying mechanisms remain unclear. Here, by integrating genome-resolved metagenomics and metatranscriptomics, we characterized the genomic potential and transcriptional activity of ARGs and MRGs in the gut microbiome of mice exposed to Sb(III)- and Sb(V)-contaminated drinking water. We found that both Sb(III) and Sb(V) significantly increased ARGs abundance, whereas only Sb(III) enhanced ARGs transcription (288.40 ± 41.67 TPM, P < 0.05). Co-selection of ARGs and MRGs was observed through metagenome-assembled genomes (MAGs) analysis, and key taxa driving this process were identified (e.g., Eubacterium_J and Lachnospiraceae_COE1). Sb(III), but not Sb(V), induced co-regulation of macrolide-lincosamide-streptogramin resistance genes and arsRABC operon. A potentially higher risk of ARG dissemination under Sb(III) stress was suggested by the increased abundance and transcription of mobile genetic elements (MGEs). This study advances our understanding of the interactions between Sb and ARGs in the gut microbiome and highlights the potential chemical species-dependent enrichment and transcriptional activation of ARGs.

Antibiotic resistance gene↗

PubMed2026

Deciphering the effects of sulfonamide antibiotics on denitrification from a metagenomic perspective: Inhibition of nitrite reduction and succession patterns of functional microorganisms.

Limited research has thoroughly elucidated the impact mechanisms of antibiotics on the denitrification process at the genomic and gene levels, which has hindered the optimization and development of nitrogen removal technology for antibiotic-containing swine wastewater. Lab-scale sequencing batch reactors were constructed in this study to treat synthetic wastewater containing different sulfonamides and nitrate. Investigations were carried out on denitrification performance, microbial community diversity, denitrifier succession patterns, and functional gene distribution. The stress of sulfonamides inhibited the nitrite reduction process, transforming complete denitrification into partial denitrification and causing significant nitrite accumulation. The average nitrogen removal efficiency in the treatment groups decreased from 81.0% ± 2.2-40.1% ± 6.1%. Alicycliphilus and Thauera were identified as the key taxa, accounting for 32.2% and 16.9% of all potential denitrifying bacteria, respectively. Although metagenome-assembled genomes (MAGs) from Thauera were enriched with genes encoding nitrate reductases (nap, nar) and nitrite reductases (nir), this genus preferentially utilized nitrate as an electron acceptor, resulting in the preferential nitrate reduction and subsequent nitrite accumulation. In contrast, Alicycliphilus MAGs developed tolerance to the sulfonamides stress during later stages, with concomitant enrichment of associated functional genes. They replaced Thauera to reemerge as the dominant group, thereby restoring complete denitrification. This study provides new insights into the regulatory mechanisms governing complete versus partial denitrification in nitrogen removal from antibiotic-containing wastewater.

Denitrifier succession↗

PubMed2026

Shifts of antibiotic resistance genes across an estuarine meandering bend and dissemination risks to offshore oceans.

Meandering is a fundamental geomorphic feature of rivers that plays a critical role in regulating pollutant attenuation. To elucidate its impact on antibiotic resistance genes (ARGs) distribution in estuarine intertidal sediments, samples were collected from both the landward side (freshwater-dominated) and the seaward side (tide-dominated) of a meander bend during ebb and flood tides. The total relative abundance of ARGs was approximately 2.7 times higher on the landward side, peaking during the ebb tide. Microbial composition analysis showed that genera Acinetobacter and Pseudomonas were dominant at the landward sites, while halophilic genera such as Marinobacter and Exiguobacterium were abundant at the seaward sites. Further analysis of metagenome-assembled genomes (MAGs) demonstrated that the dominant landward genus Acinetobacter acted as a key host of ARGs, with two of four MAGs encoding more than ten ARGs. Notably, the total relative abundance of mobile genetic elements was high but consistent between sides and tidal cycles (p > 0.05). Given this high dissemination risk, we further forecasted the ARGs transfer scenarios to oceanic settings based on a set of offshore MAGs (n = 3626). Three ARGs, i.e., acrA, vanSL, and AAC(2')-Ia, were inferred to have transfer potential, supported by neighboring MGEs detected in marine microorganisms. Analysis of the genomes of predicted recipients in the SRA database confirmed the predicted mobilizations. Together, this study highlights that the meandering planform may serve as a significant barrier, attenuating the discharge of ARGs from terrestrial sources into the marine environment.

Estuaries↗

PubMed2026

Amplicon and metagenomic sequencing reveal thifluzamide drive rhizosphere microbial structural shifts and functional adaption.

Thifluzamide (TF) is a widely used phenyl urea fungicide in rice production; however, its impacts on the structural composition and functional dynamics of the rhizosphere microbiome remain poorly understood. Here, we systematically investigated the effects of TF on the structure, interactions, and functional potential of the rice (Oryza sativa L.) rhizosphere microbiome using integrated amplicon sequencing and metagenomic approaches. TF application significantly altered both bacterial and fungal community composition, bacterial diversity was markedly reduced, whereas fungal diversity increased. With bacterial diversity markedly reduced while fungal diversity increased. Beta-diversity analyses revealed strong treatment-driven community separation, indicating pronounced TF-induced microbial restructuring. Co-occurrence network analysis demonstrated reduced complexity and connectivity in bacterial networks but increased negative co-occurrence patterns within fungal communities, suggesting contrasting stability responses between microbial kingdoms. Metagenomic profiling further revealed substantial functional shifts, including the differential enrichment of KEGG and COG pathways associated with xenobiotic metabolism. Notably, while total ARG abundance remained stable, TF exposure altered the resistome profile by selectively enriching specific classes of antibiotic resistance genes (ARGs), biocide resistance genes (BRGs), and mobile genetic elements (MGEs). Strong positive correlations between MGEs and ARGs highlighted an elevated potential for horizontal gene transfer. Metagenome-assembled genome (MAG) analysis identified specific TF-enriched bacterial taxa, including Methylophilus, Sulfurospirillum, and Azospirillum, which harbored genes involved in pesticide degradation and xenobiotic transformation. Collectively, these findings demonstrate that TF profoundly reshapes the rice rhizosphere microbiome by altering microbial diversity, interaction networks, resistance gene profiles, and functional capacities. This study provides genomic insights into fungicide-microbiome interactions, underscoring the potential ecological implications associated with TF application, while identifying candidate microbial taxa that may contribute to pesticide degradation and rhizosphere microecology resilience.

Rhizosphere↗

PubMed2026

Virus-mediated fate of antimicrobial resistance genes in livestock manure anaerobic digestion.

Antimicrobial resistance (AMR) poses a critical global health challenge, with livestock manure acting as a significant environmental reservoir for antimicrobial resistance genes (ARGs). Anaerobic digestion (AD) is a pivotal process for mitigating ARG dissemination at the livestock-environment-human interface. This study aims to elucidate the global dynamics of ARGs in AD systems, focusing on virus-host interactions and arms race, to identify actionable strategies for AMR control. We analyzed 205 metagenomic (4.5 Tb) and 36 meta-transcriptomic (640 Gb) datasets, including 15 newly generated datasets, revealing that pig manure AD harbors the highest ARG abundance (0.668 ARGs/16S rRNA), while AD systems generally exhibit limited transcriptional activation of ARGs. We constructed a viral dataset for livestock manure AD (GVD_LMAD), comprising 59,316 DNA and 727 RNA viral operational taxonomic units (vOTUs). Virus-host interactions established by CRISPR-Cas spacer, tRNA and homology matches revealed 889 lytic infections of antimicrobial-resistant bacteria (ARB) compared to only 18 ARG transduction events. Further analysis showed that the relative abundance of vOTUs assigned to the reduction role (4.11% ± 3.19%) was substantially higher than that of reproduction (0.72% ± 0.64%) and transduction (0.19% ± 0.30%), demonstrating that, among viral processes, lysis outweighs transduction in contributing to ARG abundance reduction in AD. Furthermore, an antiviral defense system (ADS) catalogue (GADSC_LMAD), derived from 2760 high-quality metagenome-assembled genomes (MAGs) containing 39,307 ADS, with ADS prevalence in ARB (7.8 ± 6.0 per MAG), indicating an intensified virus-host arms race in AD that may shield ARB from phage lysis. The resulting CRISPR-Cas immune network with expressed spacers targets foreign ARG-carrying sequences (primarily plasmids and ICEs), suggesting a mechanism that restricts horizontal gene transfer (HGT) via conjugation and transformation, despite shielding ARB from phage lysis. Collectively, these findings highlight that viral communities significantly contribute to ARG reduction through phage lysis relative to transduction, while the ADS-mediated arms race, despite protecting ARB, constructs a biological firewall that potentially limits HGT of ARGs. This study provides novel insights into virus-host dynamics as a key mechanism for controlling ARG dissemination in AD systems.

Animals↗

PubMed2026

Perfluorooctane sulfonate drives the synergistic dissemination of antimicrobial resistance and pathogenicity during sludge anaerobic digestion.

Per- and polyfluoroalkyl substances, one of the most prevalent and persistent emerging contaminants in sludge, may drive the dissemination of antimicrobial resistance and pathogenicity during sludge treatment. However, the mechanisms underlying perfluorooctane sulfonate (PFOS)-mediated propagation of antibiotic resistance genes (ARGs) and virulence factors (VFs) remain poorly understood. This study investigated the effects of PFOS (1 and 10 μg/g-dw) on ARGs dynamics and virulence risks. Quantitative PCR and metagenomic analysis revealed that PFOS stress led to the widespread enrichment of ARGs, the total abundance of mobile genetic elements (MGEs) and VFs also increased by 33.22-37.62% and 6.71-8.41%, respectively. Metagenomic binning results demonstrated that most metagenome-assembled genomes carrying ARGs or VFs simultaneously harbored MGEs. Mechanistically, excessive reactive oxygen species production and enhanced substrate-level phosphorylation for ATP generation may contribute to the increased horizontal transfer potential of ARGs under PFOS stress, which further facilitated the convergence of antimicrobial resistance and virulence traits within pathogens. Furthermore, PFOS may have hindered the negative regulation of the RhlI/RhlR quorum sensing system on the Type III secretion system, stimulating the secretion of VFs. This study elucidates the mechanisms by which PFOS promotes the dissemination of ARGs and pathogenicity during anaerobic digestion, highlighting the potentially overlooked environmental health risks of PFOS during sludge disposal.

Alkanesulfonic Acids↗

PubMed2026

Magnetite facilitates phage-bacteria interactions and phage-associated metabolic coordination for medium-chain fatty acid biosynthesis under ammonia stress.

Medium-chain fatty acid (MCFA) production from waste activated sludge (WAS) is considered to rely on the syntrophic interactions among distinct functional microorganisms. Whether phages represent an overlooked ecological component involved in MCFA biosynthesis remains unclear. MCFA production is often inhibited by high total ammonia nitrogen (TAN). Conductive materials have been proposed as effective strategies to enhance or recover MCFA production under TAN stress. Therefore, the inhibition-recovery system could provide a useful framework for investigating whether viral ecological responses are associated with MCFA-related metabolic processes. In this study, magnetite (Fe3O4) was selected as the recovery strategy of MCFA production under TAN stress. Results showed that a total of 3915 vOTUs and 118 metagenome-assembled genomes were recovered from the anaerobic bioreactors subjected to three conditions: Control (without TAN stress), TAN stress, and TAN stress with Fe3O4 presence. Under high TAN environment (∼5 g/L), MCFA production reduced by 49% (1.3 g COD/L) in comparison to that without high TAN stress. The ecological coupling between temperate phages and MCFA-related bacterial hosts was weakened, accompanied by substantial decreases in the abundance and transcriptional abundance of phage-associated auxiliary metabolic genes (AMGs) related to MCFA synthesis (e.g., fatty acid biosynthesis, acyl-chain metabolism). In the presence of Fe3O4 (i.e., 10 g/L), MCFA production was four and two times higher than those with and without high TAN stress. In addition to enhanced phage-bacteria ecological coupling and increased the abundance and transcription of AMGs related to MCFA formation, Fe3O4 increased the abundance and expressions of electron-transfer-related AMGs (e.g., cbb3-type cytochrome c oxidase, type IV pilus assembly genes) and QS-related LuxR-family and HTH-type regulators, indicating that such indirect pathway could be largely overlooked during MCFA synthesis. This is also the first-time reporting that phages could represent an ecological layer responsive to iron oxide. Analyses of publicly available metagenomes collected from MCFA-oriented anaerobic systems further confirmed that phages could be broadly associated with the metabolic processes involved in MCFA biosynthesis. Taken together, this study reveals that phages could serve as an overlooked ecological layer associated with MCFA metabolism and provide a viral-ecology perspective for understanding TAN inhibition and iron oxide-mediated recovery during WAS-to-MCFA bioconversion.

Ammonia inhibition↗

PubMed2026

Characterization of Dapalides D and E and Genomic Comparison of the Two Co-Occurring Dapalide-Producing Dapis spp.

Marine cyanobacteria are a rich source of diverse bioactive natural products, targeting proteins involved in many diseases. Here, we combined metagenomic analysis to enhance the structure elucidation process of two new cyclodepsipeptides named dapalides D (1) and E (2) from a collection of a cyanobacterial mat containing multiple Dapis species from Guam. Dapalides D/E are composed of 11 amino acids, including multiple identical units with different configurations. Enantioselective amino acid identification of the acid hydrolyzate established the identity of amino acids, including the configuration of α/β-stereogenic centers. Identification and analysis of the dapalides D/E biosynthetic gene cluster from a metagenome-assembled genome aided the elucidation of α-configuration and establishment of the order of individual building blocks, collectively revealing the total structure. Phylogenomic analysis indicates that the dapalides D/E producer belongs to Dapis sp. (Dapis sp. VPG23-80 MAG-2), which shares a 95.2% average nucleotide identity with Dapis sp. VPG23-80 MAG-1, the producer of dapalides A-C that cooccurs in the same assemblage. Dapalide D (1) showed moderate growth inhibitory activity against various cancer cell lines. This work expands the dapalide structure class and further highlights the use of combined chemical and metagenomic analyses for natural product structure elucidation.

Cyanobacteria↗

PubMed2026

Genome mining of alkaliphilic cyanobacterial consortia: identification of biosynthetic gene clusters in Sodalinema and associated heterotrophs.

Alkaline soda lakes are high-pH environments that host specialized microbial communities with potential for biotechnology and natural product discovery. We characterized three Sodalinema-dominated cyanobacterial consortia enriched from Canadian soda lakes over 510 days. Using hybrid metagenomic sequencing and metatranscriptomics across pH, alkalinity, and temperature gradients, we reconstructed high-quality metagenome-assembled genomes and assessed functional activity. All consortia converged toward cyanobacteria dominance and exhibited temperature optima between 21°C and 30°C. Phylogenetic analysis placed Sodalinema genomes within a distinct clade affiliated with Candidatus Sodalinema alkaliphilum. Genomic analysis indicated complete biosynthetic pathways for vitamin B5, vitamin B7, and the molybdenum cofactor, but incomplete pathways for vitamins B1, B9, and B12, consistent with patterns observed in Sodalinema yuhuli. Metatranscriptomic profiles showed increased expression of genes involved in phycocyanin and carotenoid biosynthesis at pH 10.2 relative to pH 8.5. Biosynthetic gene cluster analysis revealed that most secondary metabolic potential resided in heterotrophic community members. Roseinatronobacter encoded pathways for N-acyl homoserine lactones, osmoprotectants, betalactones, and prodigiosin, while Alkalimonas, Wenzhouxiangella, and members of the Kiloniellales encoded clusters for lanthipeptides, cyclodipeptides, hydrogen cyanide, and pyrroloquinoline quinone. These findings indicate functional partitioning within the consortia and highlight the contribution of heterotrophs to secondary metabolism.IMPORTANCEAlkaline soda lakes contain microbial communities adapted to high pH that remain underexplored for biotechnology. This study focuses on Sodalinema, a filamentous cyanobacterium that dominates enriched consortia from Canadian soda lakes, and its associated heterotrophic partners. We show that while Sodalinema drives primary productivity, heterotrophic bacteria encode most of the pathways for antimicrobial and signaling compounds. These interactions may support community stability and defense against competing microorganisms. By linking genomic potential with gene expression, this work identifies alkaline cyanobacterial consortia as a source of bioactive compounds and provides a framework for exploring extremophilic microbial communities for natural product discovery.

Sodalinema↗

PubMed2026

Meta-CD: a metagenomic sequencing coverage and depth calculator for target species.

Metagenomic Coverage and Depth Calculator (Meta-CD) is a convenient, biologist-friendly tool for determining coverage and depth to enhance taxonomic detection, functional profiling, and metagenome-assembled genome (MAG) recovery in metagenomics. It supports experimental design and post-sequencing analysis, modeling how genome size, relative abundance, sequencing depth, and DNA quantity influence detection of target species.

metagenomics↗

PubMed2026

Proteobacteria with chemosynthetic potential are highly prevalent in the gills of Hypoplectrus reef fishes.

Fishes host a diverse microbiome in their gills, but a broad characterization of this microbiome at the metagenomic level is lacking. Here, we apply genome-resolved metagenomics to the gills of the hamlets (Hypoplectrus spp), a group of reef fishes from the Greater Caribbean. The analysis of 353 gill samples from 15 hamlet species collected at eight locations over 13 years revealed a stark contrast between the gill microbiota and reef water microbial communities, indicating a distinct and specific gill microbiome. A total of 70 gill-associated metagenome-assembled genomes (MAGs) were recovered. These MAGs belong to 17 lineages, most of which are novel. They relate to known fish gill pathogens, fish gut microbes, free-living and biofilm-associated taxa, indicating that the gill microbiome was assembled from a collection of distinct eco-evolutionary trajectories. The MAGs harbor diverse metabolic modules, involved notably in nitrogen cycling, antibiotic production and biofilm formation, revealing a highly dynamic microbial ecosystem. One lineage in the Burkholderiaceae family was outstandingly prevalent across fish host species, sampling locations and years. Its genome encoded complete metabolic modules for carbon fixation and sulfur oxidation, indicating chemosynthetic potential. To the best of our knowledge, this is the first line of evidence that fishes may host sulfur-oxidizing chemosynthetic bacteria in their gills. The functional significance of this chemosynthetic potential for the fish host or other members of the gill microbiome remains to be established. The high prevalence of this lineage allowed to build a pangenome. It revealed large-scale geographic structure (western Caribbean, eastern Caribbean and Gulf of Mexico), which parallels the phylogenomic pattern observed in the hamlets. Overall, our findings point to complex fish host-microbe and microbe-microbe eco-evolutionary interactions in the gills that may influence fish physiology, homeostasis and immune response.

Animals↗