N Nature Microbiology · Dec 05, 2025 Interkingdom sensing of fungal tyrosol promotes bacterial antifungal T6SS activity in the murine gut Type VI secretion systems (T6SSs) are molecular machines used by bacteria to release effectors that target either host cells, competing bacteria or fungi. Regulatory mechanisms underlying antifungal T6SS activity remain unexplored. Here we show, using mouse infection with wild-type and T6SS mutant bacteria, that T6SS activity of the enteropathogen,Yersinia pseudotuberculosis(Yptb), reduces fungal prevalence in the gut microbiota and has direct activity onCandida albicans. Screening of bacterial effector mutant strains, and structural and biochemical analyses identify TfeC as an antifungal chitinase T6SS effector that can killC. albicans. In vivo experiments confirm that TfeC expression promotesYptbcolonization and reducesC. albicansabundance. We also show thatYptbsenses the fungal quorum-sensing molecule, tyrosol, through the two-component system, EnvZ–OmpR, and responds by activating T6SS4. Our findings suggest thatYptbmodulates its antifungal activities by detecting changes in fungal population density cues, revealing a mechanism of fungal–bacterial interkingdom communication mediated by fungal quorum-sensing molecules. Bacteriology Microbial ecology biology mouse experiments
N Nature Microbiology · Dec 05, 2025 Influenza A(H5N8) vaccine induces humoral and cell-mediated immunity against highly pathogenic avian influenza clade 2.3.4.4b A(H5N1) viruses in at-risk individuals Finland faced an outbreak of highly pathogenic clade 2.3.4.4b A(H5N1) avian influenza in 2023, which spread from wild birds to fur farms. Vaccinations of at-risk individuals began in June 2024 using the MF59-adjuvanted inactivated A(H5N8) vaccine (Seqirus; A/Astrakhan/3212/2020, clade 2.3.4.4b). Here, in an observational study, we assessed vaccine-induced immune responses in occupational at-risk individuals participating in the phase IV trial, including virus-specific antibody (n= 39 individuals) and T-cell (n= 18 individuals) responses. Vaccination elicited functional antibodies against the vaccine virus and two heterologous clade 2.3.4.4b strains associated with outbreaks on Finnish fur farms and dairy cattle in the United States. Among previously unvaccinated individuals, seroprotection rates against the vaccine virus were 83% (95% CI 70–97%) by microneutralization assay (titre ≥20) and 97% (90–100%) by haemagglutination inhibition assay (titre ≥40). In those previously vaccinated against avian influenza, a single dose induced seroprotection. A(H5N8)-specific memory CD4+T-cell responses were detectable, with ~5-fold increase in IFNγ secretion after two doses. These results demonstrate that the vaccine probably provides cross-protection against circulating H5 clade 2.3.4.4b viruses. EU Clinical Trial Number 2023-509178-44-00. Influenza virus Vaccines biology mouse experiments
N Nature Microbiology · Dec 04, 2025 A human gut metagenome-assembled genome catalogue spanning 41 countries supports genome-scale metabolic models Understanding the human gut microbiome requires comprehensive genomic catalogues, yet many lack geographic diversity and contain medium-quality metagenome-assembled genomes (MAGs) missing up to 50% of genomic regions, potentially distorting functional insights. Here we describe an enhanced Human Reference Gut Microbiome (HRGM2) resource, a catalogue of near-complete MAGs (≥90% completeness, ≤5% contamination) and isolate genomes. HRGM2 comprises 155,211 non-redundant near-complete genomes from 4,824 prokaryotic species across 41 countries, representing a 66% increase in genome count and a 50% boost in species diversity compared to the Unified Human Gastrointestinal Genome catalogue. It enabled improved DNA-based species profiling, resolution of strain heterogeneity and survey of the human gut resistome. The exclusive use of these genomes improved metabolic capacity assessment, enabling high-confidence, automated genome-scale metabolic models of the entire microbiota and revealing disease-associated microbial metabolic interactions. This resource will facilitate reliable functional insights into gut microbiomes. Metagenomics Microbiome biology
N Nature Microbiology · Dec 04, 2025 Phage resistance mutations in a marine bacterium impact biogeochemically relevant cellular processes Phage–bacteria interactions shape ecology and biogeochemistry across biomes. Resistance, arising from their evolutionary arms race, is well documented for receptor mutations, but other resistance mechanisms and their ecological implications remain unexplored. Here we isolated, sequenced and characterized 13 phage-resistant mutants of marineCellulophaga baltica(Flavobacteriia). Mechanistically, mutations in surface proteins provided broad and complete extracellular resistance against multiple phages through decreased adsorption. Intracellular mutations affecting serine, glycine and threonine metabolism produced narrower resistance against a single phage, permitting viral DNA replication, and, in one mutant, were shown to be lipid mediated. Putative ecosystem impacts inferred from in vitro experiments include: (1) altered carbon utilization for all mutants, but especially by surface ones, (2) increased metabolite secretion for one modelled intracellular mutant (including experimentally verified acetate) and (3) increased ‘stickiness’ for all mutants, with surface mutants also sedimenting faster. Our findings highlight new resistance mechanisms and suggest that the phage–host arms race could result in ecosystem-level biogeochemical impacts in marine microorganisms. Bacteriophages Microbial ecology Phage biology Water microbiology biology
N Nature Microbiology · Dec 03, 2025 Transcription co-inhibition alters drug resistance evolution and enhancesMycobacterium tuberculosisclearance from granulomas Mycobacterium tuberculosis(Mtb), the causative agent of tuberculosis, remains the deadliest human pathogen. Treatment is hampered by drug resistance and the persistence of slow-growing or non-replicating populations. Rifampicin, a cornerstone of first-line therapy, inhibits transcription during promoter escape, but resistance mutations undermine efficacy and drive resistance spread. We revisited the transcription cycle as an antibacterial target by characterizing AAP-SO2, an RNA polymerase inhibitor with whole-cell activity against Mtb. AAP-SO2slows the nucleotide addition cycle, disrupting elongation and termination. Rifampicin-resistant mutations impose fitness costs by perturbing the balance of these steps, creating exploitable weaknesses. Inhibition of transcription with AAP-SO2reduced the evolution of rifampicin resistance and was especially effective against the most common resistant mutant. Combination treatment with rifampicin and AAP-SO2synergistically killed non-replicating Mtb in an ex vivo rabbit granuloma model. These findings show that exploiting functional vulnerabilities of the transcription cycle can counter rifampicin resistance and improve clearance of recalcitrant Mtb populations. Antibiotics Cryoelectron microscopy Pathogens Transcription biology
N Nature Microbiology · Dec 03, 2025 Gut microbiome-mediated transformation of dietary phytonutrients is associated with health outcomes Food, especially plant-based diet, has complex chemical diversity. However, large-scale phytonutrient-metabolizing activities of gut bacteria are largely unknown. Here we integrated and systematically analysed multiple databases containing information on enzymatic reactions and food health benefits, and 3,068 global public human microbiomes. Transformation of 775 phytonutrients from edible plants was associated with enzymes encoded by diverse gut microbes. In vitro assays validated the biotransformation activity of gut species, for example,Eubacterium ramulus. The biotransformation of phytonutrients demonstrated high interpersonal and geographical variability. Machine learning models based on 2,486 public case–control microbiomes, using the abundances of enzymes associated with modification of phytonutrients present in health-associated foods, discriminated the health status of individuals in multiple disease contexts, suggesting altered biotransformation potential in disease. We validated the association of microbiome-encoded enzymes with the anti-inflammatory activity of common edible plants by combining metagenomics and metatranscriptomics analysis in specific-pathogen-free and germ-free mice. These findings have implications for designing precise, personalized diets to guide an individual towards a healthy state. Microbial communities Computational biology and bioinformatics biology mouse experiments
