Here, analysis of the proportion of Fn subspecies by niche found that of the four Fn subspecies, only Fna is significantly associated with the CRC niche (two-sample z-test, two-tailed, P = 0.0232; Fig. 1f), validating previous studies28, whereas Fnn is significantly enriched in the oral niche (two-sample z-test, two-tailed, P = 0.00932; Fig. 1f). This evidence concerns the gene FN1 and colorectal carcinoma.