Fecal microbiota transplantation from different pig breeds alters fat deposition and gut microbiota in mice

Gut microbiota plays a vital role in nutrient digestion, energy metabolism, and immune regulation in pigs. However, the core bacterial species influencing fat deposition remain poorly defined due to the complexity and diversity of the intestinal microbial ecosystem. In this study, healthy Putian Black (PT) pigs and Duroc $\times$ Landrace $\times$ Yorkshire (DLY) pigs of similar ages were used as fecal microbiota transplantation (FMT) donors, with male ICR mice as recipients. A control group (CM) received saline, while the experimental groups were gavaged fecal suspensions from PT pigs (PM) or DLY pigs (DM). Results showed that intramuscular fat content, triglyceride levels, and adipogenic gene expression (PPARG, FABP4, LPL, ATGL) were extremely significant higher in the PM group than in the DM group (P<0.01). 16 S rRNA sequencing revealed that both PM and DM groups had lower Firmicutes abundance but higher Bacteroidetes abundance compared to the CM group (P<0.05). Notably, the PM group exhibited higher Firmicutes and lower Bacteroidetes abundance than the DM group (P<0.05). Correlation analysis identified S_uncultured_bacterium_g_Prevotella as negatively correlated with FASN and DGAT2 expression (P<0.01), while Lactobacillus species showed positive correlations with PPARG, FASN, and ATGL expression (P<0.05). These findings demonstrate that FMT alters gut microbiota composition and host gene expression, thereby influencing fat deposition, with Prevotella and Lactobacillus emerging as potential key genera. KEY POINTS: $\bullet$ FMT resulted in extremely significant higher intramuscular fat content in the PM group compared to the DM group. $\bullet$ Lactobacillus may be a key genus regulating fat deposition in PT pigs. $\bullet$ Prevotella may be a key genus regulating fat deposition in DLY pigs.