Fig. 1: Global bacterial features of six datasets.

a Left panel: PCoA plot of bacterial species in PD and controls in six countries with Bray–Curtis dissimilarity. Circles and triangles indicate controls and PD, respectively. Countries are color-coded. Right panel: PCoA plot showing the center of gravity and the standard error of the overall compositions of bacterial species in six datasets in PD and controls with Bray–Curtis dissimilarity. Both panels have the same x- and y-scales. b Forest plot of α-diversities of bacterial species in six datasets. FEM and REM represent fixed and random effect models, respectively. The square sizes represent the number of samples. Bars represent 95% confidence interval. Diamonds represent the mean and 95% confidence interval. P-values of FEM and REM and I² are indicated. c The cumulative frequency plots of the relative abundance at the species level in six datasets. The number of identified bacterial species in controls and PD in each dataset is indicated by a small circle at the end of the curve.