Tumor tissue-specific bacterial biomarker panel for colorectal cancer: Bacteroides massiliensis, Alistipes species, Alistipes onderdonkii, Bifidobacterium pseudocatenulatum, Corynebacterium appendicis.

Human microbiome studies have shown diversity to exist among different ethnic populations. However, studies pertaining to the microbial composition of CRC among the Indian population have not been well explored. We aimed to decipher the microbial signature in tumor tissues from North Indian CRC patients. Next-generation sequencing of tumor and adjacent tissue-derived bacterial 16S rRNA V3-V4 hypervariable regions was performed to investigate the abundance of specific microbes. The expression profile analysis deciphered a decreased diversity among the tumor-associated microbial communities. At the phyla level, Proteobacteria was differentially expressed in CRC tissues than adjacent normal. Further, DeSeq2 normalization identified 4 out of 79 distinct species (p < 0.005) only in CRC, Bacteroides massiliensis, Alistipes onderdonkii, Bifidobacterium pseudocatenulatum, and Corynebacterium appendicis. Thus, the findings suggest that microbial signatures can be used as putative biomarkers in diagnosis, prognosis and treatment management of CRC.