Bacteroides fragilis

Abstract

The colonic microbiota is a complex and densely populated ecosystem, whose metabolic activity influences the nutritional status and health of the host through diverse mechanisms. The microbiota of adults is dominated by five phyla, more than 80% of the species belonging to just two of them, Firmicutes and Bacteroidetes. The genus Bacteroides, is an anaerobic, bile-resistant, non-spore forming gram negative rod that accounts for up to 20-50% of the total gut microbiota in humans. In the gut, these microorganisms generally maintain a complex and beneficial relationship with the host; however, when escape this location, they can act as significant clinical pathogens, displaying a high rate of associated mortality. The ability of Bacteroides to behave as beneficial or harmful microorganism is largely linked to its capacity to adapt and thrive in different environments. Bacteroides species have the ability to sense and adapt to nutrient availability, being among the nutritionally most versatile microorganisms in the human gut. These bacteria also have multiple cellular pump systems to expel outside and release from the cell toxic compounds, and they can interact with the host immune system, being by this way able to control other competing microorganisms