Gut Fungal Community Modulates Fat Deposition in Ningxiang Pigs: Species-Specific Regulation via the Glucose-SCFAs Metabolic Axis.

Despite limited understanding of gut fungal roles in fat deposition among indigenous pig breeds, a comparative study between high-fat-accumulating Ningxiang (NX) pigs and lean-type Duroc × Landrace × Yorkshire (DLY) pigs reveals a fungal-driven regulatory mechanism. NX pigs exhibited significantly higher fat percentage, elevated serum glucose, and markedly reduced total colonic short-chain fatty acids (SCFAs) compared to DLY pigs (all < 0.001), with butyrate showing the most pronounced decrease. Beta-diversity confirmed distinct fungal communities ( = 0.002), where NX pigs were enriched with and , while DLY pigs harbored dominant . Strong correlations were observed: NX-enriched fungi positively correlated with glucose and negatively with SCFAs, whereas strongly associated with SCFAs ( < 0.001). FUNGuild analysis linked / to enhanced polysaccharide degradation and glucose bioavailability. The findings propose a gut fungal-mediated "Glucose-SCFAs axis": NX-enriched fungi elevate glucose (promoting lipogenesis) and suppress SCFAs (reducing butyrate-mediated adipocyte inhibition), whereas in DLY pigs enhances SCFAs-induced lipolysis. Crucially, we demonstrate that fungal modulation primarily drives fat deposition differences between breeds, offering novel probiotics/antifungal strategies for precision swine breeding.