30-50% of your faecal matter is said to be Bacteroides fragilis! This organism is a commensal found in the terminal ileum, and very prolific in the colon. This bacterium offers many benefits to its carrier:
- production of butyrate, acetate, propionate…
- bile biotransformation
- possible competence with pathogens for niche physical occupation (no more room!) and resources
and possibly several other unknowns.
Sometimes it may also act as a opportunistic pathogen, for example found extensivenly in some patients with diarrhoea (especially children and adults with bowel inflamatory disease).
A very interesting thing of this microbe is the ability to degrade almost any known carbohydrate, they literally have an arsenal of enzymes involved in sugars metabolism.