The aim of this study was to analyze the differences in gut microbiota, metabolites, and metabolic pathways between healthy individuals and patients with colorectal cancer

We conducted metagenomic and untargeted metabolomic sequencing analyses of fecal samples collected from patients with CRC (n=26) and healthy controls (n=20) and observed an elevated abundance of potentially pathogenic bacteria such as Escherichia, Fusobacterium, Klebsiella, Lachnoclostridium, Lachnoclostridium, Shigella and Enterococcus alongside reduced abundance of probiotic bacteria including Lactococcus, Lachnospira and Eubacterium in patients with CRC. Metabolites and metabolic pathways related to glycolysis, methane generation, beneficial amino acid degradation, and linoleic acid degradation were significantly elevated in CRC patients compared with healthy controls. Notably, differential analysis identified N-methylserotonin as one of the most significantly differentially expressed metabolites between the two group, and no previous studies have reported the relevance of this metabolite to tumors. Furthermore, N-methylserotonin levels exhibited a significant positive correlation with the abundance of probiotic bacteria such as Lachnospira, as well as with the degree of tumor differentiation, suggesting its potential as a non-invasive biomarker for CRC diagnosis.