Because oxygen is not required, it is an alternative to aerobic respiration. Over 25% of bacteria and archaea carry out fermentation.[2][3] They live in the gut, sediments, food, and other environments. Eukaryotes, including humans and other animals, also carry out fermentation.[4]
Fermentation is important in several areas of human society.[2] Humans have used fermentation in production of food for 13,000 years.[5]Humans and their livestock have microbes in the gut that carry out fermentation, releasing products used by the host for energy.[6] Fermentation is used at an industrial level to produce commodity chemicals, such as ethanol and lactate. In total, fermentation forms more than 50 metabolic end products[2] This process highlights the power of microbial activity.
^Liu L, Wang J, Rosenberg D, Zhao H, Lengyel G, Nadel D (2018). "Fermented beverage and food storage in 13,000 y-old stone mortars at Raqefet Cave, Israel: Investigating Natufian ritual feasting". Journal of Archaeological Science: Reports. 21: 783–793. doi:10.1016/j.jasrep.2018.06.011.
^Bergman EN (April 1990). "Energy contributions of volatile fatty acids from the gastrointestinal tract in various species". Physiological Reviews. 70 (2): 567–590. doi:10.1152/physrev.1990.70.2.567. PMID2181501.