Microbial Community Dysbiosis and Functional Perturbations in Colorectal Cancer Patients:

Abstract

Colorectal cancer (CRC) has a very close association with Dysbiosis, a phenomenon causing alterations in the microbiome of gut.  Some of the recent research implicates that gut microbiome plays a key role in colorectal carcinogenesis, where CRC patients often displays an imbalance in gut bacteria (dysbiosis) marked by depletion of beneficial microbes and proliferation of pro-inflammatory microbial species. Aim of our study was to carry out gut microbiome profiling of CRC patients alongside publicly accessible healthy datasets to inspect changes in microbial diversity, its taxonomic shifts, and functional obstructions. We carried out 16S rRNA gene sequencing of faecal samples, assessing alpha diversity and beta diversity, and used PICRUSt2 for predicting microbial metabolic pathways and metabolites. The CRC gut microbiome showcased a significant reduction in alpha diversity, pointing out an anticipated loss of microbial richness. Taxonomic profiling revealed depletion of health-associated commensals, notably short-chain fatty acid (SCFA) producers such as Faecalibacterium, alongside an enrichment of opportunistic and potentially pathogenic genera. Functional prediction analysis indicated corresponding losses in microbial metabolic capacity: CRC samples were deficient in pathways for SCFA biosynthesis (e.g., butyrate production) and B-vitamin biosynthesis (e.g., folate, cobalamin), among other nutrient metabolism pathways, suggesting a collapse of beneficial functions. Altogether, dysbiosis linked to CRC was evidently clear in both community structure and in its function, with almost half of microbial pathways significantly altered. These findings emphasize the relevance of gut microbiome disturbances with CRC. The depletion of beneficial microbes and their metabolites in CRC patients has potential clinical implications, from using microbial signatures as non-invasive diagnostic markers to restoring microbial balance as a therapeutic strategy.