A high-resolution spatial model of the primate gut microbiome defines niche-specific functions and host-adapted microbial metabolism

encoded expanded carbohydrate-active enzyme (CAZyme) repertoires specialized for degradation of complex plant polysaccharides, consistent with dietary and other host-associated adaptation. Along the gastrointestinal tract, microbial load and diversity followed pronounced spatial gradients, although the low-biomass stomach retained unexpectedly high taxonomic and functional diversity. Mucosal communities largely mirrored luminal microbiota at broad taxonomic scales but exhibited distinct species-level signatures associated with niche-specific functional specialization. The monkey large intestine was further enriched in the immunomodulatory bile acid isoallo-lithocholic acid (isoalloLCA), with candidate biosynthetic genes identified in previously uncharacterized microbial lineages. Together, these findings establish a high-resolution framework of the primate gut microbiome and reveal how spatial organization and host-associated selection shape microbial metabolism and host-microbe interactions relevant to gut health.