Fig. 2

a The Rarefaction Curve tends to be flat, which indicates that the sequencing of each sample was sufficient to reflect the species diversity in the sample. b The species richness of the gallstone group was less than that of the control group using the same number of sequences. c and d The rank abundance curve of most samples in the gallstone group was shorter than that in the control group in the horizontal direction, and the shape of the curve was steeper. e The curve tends to be flat, which indicates that the amount of sequencing data is large enough to reflect the biological diversity of the sample. f and g The Shannon index of the gallstone group was significantly smaller than that of the control group (3.04 ± 0.38 < 3.28 ± 0.31, p < 0.05). h The Simpson index was significantly greater in the gallstone than in the control group (0.11 ± 0.04 > 0.08 ± 0.03, p < 0.05). Data are expressed as the mean ± SD, *p < 0.05, **p < 0.01. Statistically significant differences (p < 0.05) between the two groups were determined by Student’s t test