In vitro digestion and fermentation characteristics of Agrocybe cylindracea polysaccharides and their interaction with the gut microbiota

Agrocybe cylindracea polysaccharides (ACP) are bioactive macromolecules with potential prebiotic properties, yet their digestive stability and microbiota-modulating mechanisms remain unclear. This study aimed to systematically evaluate the in vitro digestion and fermentation characteristics of ACP and its interaction with the gut microbiota. The average molecular weight of ACP was determined to be 2.39 × 10 5  Da, and its primary monosaccharides were glucose (53.93 ± 0.65 %) and galactose (27.36 ± 0.17 %), with a significant content of 1,3-Glc linkages. During colonic fermentation, ACP was selectively utilized by gut bacteria, leading to a significant pH reduction and increased production of short-chain fatty acids (SCFAs), particularly acetate, propionate, and butyrate (total SCFAs: 48.7 mM at 24 h). Furthermore, ACP modulated the composition of gut microbiota by enhancing the relative abundance of beneficial bacteria such as Paraprevotella (400-fold increase) and Bacteroides (3.6-fold increase), while suppressing opportunistic pathogens like Fusobacterium and Escherichia . The correlation analysis conducted between SCFAs and gut microbiota indicated the prebiotic potential of ACP, particularly in enriching SCFA-producing bacteria, including Clostridium_sensu_stricto , Gemmiger, Paraprevotella , and Bacteroides . These findings highlight ACP as a structurally stable polysaccharide capable of modulating gut microbiota composition and metabolic activity, supporting its application in functional foods targeting gut health.