Role of the Gut Microbiota in the Digestive Tract Diseases

The gastrointestinal microbiome is established during foetal development and continuously altered throughout the life span. The microbial ecosystem is complex and it plays a vital role in human health, including digestion and immune response. The human gastrointestinal environment is colonized by numerous species of microorganisms with substantial variations. The symbiotic interactions between host metabolism and the resident microflora contribute largely to the maintenance of gut homeostasis and perturbations in the microbial balance (dysbiosis) have been correlated with a wide array of diseases. Various factors have been implicated in microbial dysbiosis including environmental changes and drug effects. This review discusses the microbial composition of the gastrointestinal environment and the factors causing microbial dysbiosis. It highlights the evolution of the microbiota in the human gut with special emphasis on the role of different bacterial species in the gut homeostasis. In addition, it aims to provide critical analysis on the role of microbiota in gut related diseases, especially irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), and Crohns’ disease. A better understanding of the gut ecosystem would enable more targeted interventions in gut microbial composition to prevent or manage these disorders by restoring gut homeostasis.