For a study, it was determined that complex and diverse bacterial populations inhabit the human large intestine. However, the link between commensal gut bacteria and adenomas (precursors to colon cancer) remains unknown. The researchers sought to examine variations in community composition associated with colorectal adenomas and define adherent bacteria in the normal colon. In a cross-sectional investigation, adhering bacteria were assessed in the normal colonic mucosa of 21 adenoma and 23 non-adenoma participants. The 16S rRNA genes were characterised by terminal restriction fragment length polymorphism, clone sequencing, and fluorescent in-situ hybridization studies. For phylogenetic and taxonomic analyses, 335 clones were sequenced and processed. UniFrac and similarity matrix analysis were used to assess differences in bacterial composition between patients and controls. Firmicutes (62%) were the most prevalent phylum, followed by Bacteroidetes (26%), and Proteobacteria (11%). The bacterial makeup of the patients and controls differed considerably (UniFrac P<0.001). When comparing cases to controls, the researchers found a considerably increased abundance of Proteobacteria (p<0.05) and a significantly reduced abundance of Bacteroidetes (P<0.05). Case individuals had higher proportions of Dorea spp. (P<0.005), Faecalibacterium spp. (P<0.05), and lower proportions of Bacteroides spp. (P<0.03) and Coprococcus spp. (P<0.05) than controls at the genus level. Bacterial diversity and richness were higher in cases than in controls. The findings suggested that changes in bacterial community composition linked to adenomas might have played a role in the development of colorectal cancer. The findings could lead to strategies for manipulating the microbiome to prevent colorectal adenomas and cancer, as well as identifying high-risk individuals.