Fig. 1
Gut bacterial characteristics in CCHD patients and HCs. A The comparison of gut bacterial α-diversity between CCHD and HC groups (Wilcoxon rank sum test). B PCoA of the Bray–Curtis distances based on bacterial composition at the species level revealed significant difference between CCHD and HC groups (PERMANOVA). Bacterial taxa that significantly correlated with the PC-axes with Spearman’s correlation coefficient > + 0.35 or < − 0.35 (with a maximum of the top six for each quadrant) are graphed as contributors that drive the separation. The length of the arrow represents the degree of correlation to the PC-axes. The distribution and density of samples projected onto PC-axes are displayed in violin plots and assessed individually using the Wilcoxon rank sum test. C Fecal samples of the overall study cohort (n = 95) are clustered into enterotype 1 and enterotype 2 by using PCoA of the Jensen–Shannon distances at the genus level. D Box plots showing the relative abundance of the top genera in each enterotype (Wilcoxon rank sum test). E Network illustrating the correlations between enterotype enriched species. Only the top ten most abundant species enriched in each enterotype are displayed, with orange line indicating positive correlation and gray line indicating negative correlation (Spearman, P < 0.05, r > 0.6). Pie charts showing the distribution of neonates with CCHD and HCs in respective enterotypes, with the adjacent box plots showing the relative abundance of Bifidobacterium and Enterococcus in both the groups. F Relative abundances of 58 bacterial species responsible for discriminating the CCHD and HC groups. The genus taxonomy of each species is shown on the right.“#” indicates bacterial species enriched in HC group; whereas “†” indicates species enriched in CCHD group. G Co-occurrence network deduced from bacterial taxa differentially enriched in the CCHD and HC groups. Red edges indicate positive correlations and blue edges indicate negative correlations (Spearman, P < 0.05, r > 0.6). *P < 0.05, **P < 0.01, ***P < 0.001. PCoA, principal coordinates analysis; CCHD, critical congenital heart disease; HC, healthy control