Fig. 1

A The 100% stacked column chart of the relative abundance at the species level in CRC patients and healthy controls. The X-axis represents the CRC and control groups. The value of each species percentage in the Y-axis represents the mean value of relative abundance from each CRC and control cohort. The relative abundance represents the percentage of each species per sample. B Alpha diversity was evaluated by the Shannon index, Pielou evenness, Simpson index, and Equitability evenness. The solid lines indicate the faecal samples from CRC patients and their matched healthy controls. The difference in alpha diversity was calculated by the Wilcoxon signed‒rank test. C PCoAs of Bray‒Curtis distances on species composition, calculated between CRC and healthy controls. Each dot represents a patient with CRC and controls. Points clustered in light blue and pink eclipses represent the gut microbial composition of the CRC and controls, respectively. The boxplots around the PCoA plot represent the Bray‒Curtis distances of Axis1 (the top boxplot) and Axis2 (the right-sided boxplot). Differences in Bray‒Curtis distances of both Axis1 and Axis2 were calculated between the CRC and controls using the Wilcoxon Mann‒Whitney test, and p < 0.05 was considered statistically significant. D Visualization of dispersion differences in microbial composition between the CRC and control groups. Points in light blue and pink represent the gut microbial composition of the CRC and controls, respectively. The red and dark blue points indicate the centroids of all microbial species in each CRC and control group, respectively. The dashed line represents the spatial distance between the centroids and each sample. PERMANOVA was performed, and p < 0.05 was considered statistically significant. CRC: colorectal cancer; PCoAs: principal coordinate analyses