Microbiota-directed fibre activates both targeted and secondary metabolic shifts in the distal gut

Beneficial modulation of the gut microbiome has high-impact implications not only in humans, but also in livestock that sustain our current societal needs. In this context, we have tailored an acetylated galactoglucomannan (AcGGM) fibre to match unique enzymatic capabilities of Roseburia and Faecalibacterium species, both renowned butyrate-producing gut commensals. Here, we test the accuracy of AcGGM within the complex endogenous gut microbiome of pigs, wherein we resolve 355 metagenome-assembled genomes together with quantitative metaproteomes. In AcGGM-fed pigs, both target populations differentially express AcGGM-specific polysaccharide utilization loci, including novel, mannan-specific esterases that are critical to its deconstruction. However, AcGGM-inclusion also manifests a butterfly effect, whereby numerous metabolic changes and interdependent cross-feeding pathways occur in neighboring non-mannanolytic populations that produce short-chain fatty acids. Our findings show how intricate structural features and acetylation patterns of dietary fibre can be customized to specific bacterial populations, with potential to create greater modulatory effects at large. Here, the authors tailor an acetylated galactoglucomannan (AcGGM) fibre from spruce wood to specifically enrich Roseburia and Faecalibacterium - beneficial species which have the enzymatic machinery to breakdown the fibre and generate butyrate. They subsequently perform a piglet feeding trial, metagenomics and metaproteomics, together showing that AcGGM-fed pigs exhibit not only increased Roseburia and Faecalibacterium populations with AcGGM-specific mannan-specific esterases, but also secondary metabolic pathways.