Fig. 1

a Preoperative comparison of OTU level between the two groups. PCA1 is the significance of the sample in the first principal component (abscissa); PCA2 is the significance of the sample on the second principal component (ordinate). The P value represents the significance of the sample in this principal component. b Postoperative comparison of OTU level between the two groups. PCA1 is the significance of the sample in the first principal component (abscissa); PCA2 is the significance of the sample on the second principal component (ordinate)