16S rRNA sequences from human colon samples

The tumor microenvironment of colorectal carcinoma is a complex community of genomically altered cancer cells, non-neoplastic cells, and a diverse collection of microorganisms. Each of these components may contribute to carcinogenesis, however the role of the microbiota is the least well understood. To determine the microbial composition of human colorectal cancer, we examined a cohort of 95 paired specimens of colon tumors and normal colonic DNA by microbial 16S rDNA sequencing. Colorectal tumors were associated with broad phylum-level changes including the depletion (i.e. reduced relative abundance) of Firmicutes and Bacteroidetes as well as a strong enrichment of Fusobacterium species.