Two microbiome studies published recently advance links between gut communities and disease. Liu et al., in Molecular Cancer, reported that gut microbial metabolites modulate antitumor immunity, illuminating metabolite-driven mechanisms that could be targeted to enhance immune-oncology therapies. The work maps specific microbial pathways that influence immune cell activity within the tumor microenvironment. Complementing mechanistic work, Dong et al. expanded gut microbial genome catalogs from Chinese cohorts, uncovering population-specific strains and gene content that broaden reference databases for microbiome studies. Together, the papers improve mechanistic understanding and provide richer genomic resources for translational microbiome research.