Fig. 5

The UDP-GlcNAc synthesis/recycling pathway is depleted in PD-RBD(+) and negatively correlated with bacterial biofilm formation. A Schematic representation of the UDP-GlcNAc synthesis and recycling pathway, which is related to the amino sugar and nucleotide sugar metabolism (KEGG pathway map00520) and peptidoglycan biosynthesis (map00550) pathways. Solid red arrows denote reactions catalyzed by enzymes encoded by genes exhibiting significant differences in the DA analyses, whereas solid black arrows signify reactions facilitated by those without significant differences. B Relative abundances of significantly different genes marked by solid red arrows in (A). Pie charts represent taxonomic contributions to each gene across groups. C Scatter plot of centered log-ratio (clr) transformed abundances for csgD and glmU genes, which are essential for biofilm formation and UDP-GlcNAc synthesis, respectively. These genes show a negative correlation (ρ = − 0.32, p = 4.0E-4). D Distribution of the four subject categories based on the clr-transformed abundances of csgD and glmU genes across groups. Fisher’s exact test was used for statistical analysis. q < 0.1; *q < 0.05; ***q < 0.001 for DA analysis. **p < 0.01 for Fisher’s exact test. ns not significant, ρ Spearman’s rank correlation coefficient, GlcN-6P glucosamine 6-phosphate, GlcN-1P glucosamine 1-phosphate, GlcNAc N-acetylglucosamine, GlcNAc-6P GlcNAc 6-phosphate, GlcNAc-1P GlcNAc 1-phosphate, UDP-GlcNAc uridine diphosphate-GlcNAc, DA differential abundance, PD Parkinson’s disease, RBD rapid eye movement sleep behavior disorder