Metagenomic analysis of gut microbiota of patients with colorectal cancer at the Fedral Medical Center (FMC), Abeokuta, Ogun State, Nigeria
The gastrointestinal microbiota, composed of a large population of microorganisms, is often considered a "forgotten organ" in human health and diseases. Increasing evidence indicates that dysbiosis of the intestinal microbiota is closely related to the development of colorectal cancer (CRC) which is one of the major gastrointestinal tract cancers in Nigeria. The advent of sequencing technology has expanded our knowledge of the roles of human gastrointestinal microbiota in initiating and promoting the development of CRC. Different hypothesis models have been proposed to illustrate the complex relationship between the gastrointestinal microbiota and CRC. Recent studies have identified Streptococcus bovis, enterotoxigenic Bacteroides fragilis, Fusobacterium nucleatum, Enterococcus faecalis, Escherichia coli, and Peptostreptococcus anaerobius as CRC candidate pathogens. However, there is paucity of information on the relationship between the gastrointestinal microbiota and CRC in Nigerian population. Therefore, this study was designed to investigate changes in intestinal bacteria in healthy subjects and patients with CRC. Fecal samples were collected from healthy and CRC subjects at the Federal Medical Centre, Abeokuta with the study ethical approval number FMCA/47O/HREC/01/2021/23. Genomic DNA was extracted from the fecal samples with magnetic bead extraction and the whole genome was sequenced using a Nanopore MinION sequencer. Metagenomic analysis was performed on the fecal samples to study the bacterial community structure, relative abundance, differentially abundant bacteria, association networks, taxonomic profiling, and specialty gene expression. The identified strains and marker genes in this study discriminates CRC from the healthy subjects. The findings of this study lay the foundation for the clinical values of gastrointestinal microbiota and novel strategies for preventing, diagnosing and treating CRC in Nigeria.