quality:corruption
Biological role and prevalence

Fermentation is used by organisms to generate ATP energy for metabolism. One advantage is that it requires no oxygen or other external electron acceptors, and thus it can be carried when those electron acceptors are absent. A disadvantage is that it produces relatively little ATP, yielding only between 2 to 4.5 per glucose compared to 32 for aerobic respiration.

Over 25% of bacteria and archaea carry out fermentation. This type of metabolism is most common in the phylum Bacillota, and it is least common in Actinomycetota. Their most common habitat is host-associated ones, such as the gut.

Animals, including humans, also carry out fermentation. The product of fermentation in humans is lactate, and it is formed during anaerobic exercise or in cancerous cells. No animal is known to survive on fermentation alone, even as one parasitic animal (Henneguya zschokkei) is known to survive without oxygen.