Central Nervous System and the Colonic Bioreactor: Analysis of Colonic Microbiota in Patients with Stroke Unravels Unknown Mechanisms of the Host Defense after Brain Injury

Abstract

by life threatening septic complications. The origin of the quickly changing polymicrobial infectious events is the endogenous flora from the skin, oro-pharynx, uro-genital region and colon. The colon is the largest reservoir for bacteria. The colon is physiologically seen a bioreactor. Here, bacteria ferment waste products of digestion, recycle water and electrolytes, and win additional energy via short fatty acids and lactate. Bacterial growth is actively promoted, leading to concentrations of 10 12 bacteria per mL of stool. The optimal growth conditions attract, besides fermentative strains, all microorganisms that are able to exist in this environment, leading to an unprecedented diversity of more than 5,000 species in each healthy colon. Most species are probably harmless wanderers brought into the colon by accident, Central Nervous System and the Colonic Bioreactor: