Fig. 4

Interactions among gut microbes, SCFA-related synthetic enzyme genes, bacterial functions, and putative producers of SCFAs in AF. (a-c) The partial least squares structural equation modeling (PLS-SEM) models showing the mediation effect of short-chain fatty acids (SCFAs)-related synthetic function in the total effect of gut microbiota diversity (a) and key bacteria (b) in atrial fibrillation (AF), and the mediation effect of potential systematic inflammation reflected by high-sensitive c reactive protein (hsCRP) in the total effect of SCFA-related synthetic function in left atrial enlargement in AF (c). Path coefficients are indicated; indirect effect and variance accounting for the score are found below a given mediator (*P < 0.05; **P < 0.01). (d) Interrelationship of the SCFA-related synthesis potential of different bacteria. The correlation network obtained by Spearman correlation analysis depicts key intestinal bacteria with significant associations with indicated SCFA-related synthetic enzyme genes, linked to respective KEGG orthologues (KOs). Red and blue indicate positive and negative correlations, respectively; line thickness reflects correlation strength. FDR corrected p < 0.05 (*) or 0.01 (**) was considered statistically significant