However, the microbiota must rely upon anaerobic metabolism, or fermentation, to generate energy and create important molecules without oxygen. The second challenge these microbes face is the speed at which this metabolism must take place. Food moves through our digestive tract rapidly, and a competitive ecosystem forces bacteria to quickly consume any available passing nutrients. The strategy utilized by the most prevalent human gut-residing bacteria to solve these problems is rapid fermentation of MACs, one of the most abundant forms of energy within the colon.
