GAP-0 promotes intestinal health by interacting with the gut microbiota to increase energy metabolism

Abstract

Background Ganoderma applanatum is a well-known edible mushroom whose polysaccharides can improve intestinal health. At present, the mechanism of G. applanatum active polysaccharides and the interactive relationship between gut microbiota active polysaccharides require further investigation. Results We dissected the active ingredient structure and mechanism of the active G. applanatum polysaccharide (GAP). GAP-0 had a →3)-β-Glcp-(1→4)-α-Glcp-(1→ main chain and 6→2)-α-D-Manp-(1→, 6→4)-α-Glcp-(1→4)-α-GalA-(1→, and 6→1)-α-D-Glcp-(6→ side chains. We found that GAP-0 mainly influenced ribosomal large subunit biogenesis, oxidative phosphorylation, ATP metabolic process, ATP synthesis coupled electron transport and generation of precursor metabolites and energy in the colon transcriptome. Through germ-free mouse experiments, we found that GAP-0 was dependent on the gut microbiota. GAP-0 was first utilized by the gut microbiota and demonstrated a protective effect on DSS-induced colitis. In healthy mice, RikenellaceaeRC9 gut group, Bifidobacterium, Oscillibacter and Negativibacillus participated in utilizing GAP-0, and increased short-chain fatty acids (SCFAs) production. The increased acetic acid content was positively related to RikenellaceaeRC9 gut group and Bifidobacterium, valeric acid was positively related to LachnospiraceaeNK4A136 group, RikenellaceaeRC9 gut group and Parasutterella, propionic acid was positively related to Negativibacillus, butyric acid was positively related to Bifidobacterium, isovaleric acid was positively related to Bifidobacterium, and valeric acid was positively related to Negativibacillus. Moreover, Lachnoclostridium, Mucispirillum, Adlercreutzia and GCA900066575 utilized GAP-0 preferentially. Among them Adlercreutzia was positively related to butyric acid and acetic acid, while Mucispirillum was positively related to butyric acid, acetic acid, propionic acid and valeric acid. Conclusions By evaluating the active ingredient structure, GAP-0 was found to mainly improve immunity by increasing energy metabolism. These protective effects were exerted in a gut microbiota-dependent manner. GAP-0 was first utilized by the gut microbiota and showed a protective effect against DSS-induced colitis.