Anaerobic organism

*Spinoloricus cinziae*, a metazoan that metabolises with hydrogen, lacking mitochondria and instead using hydrogenosomes.

An anaerobic organism or anaerobe is any organism that does not require molecular oxygen for growth. It may react negatively or even die if free oxygen is present. In contrast, an aerobic organism (aerobe) is an organism that requires an oxygenated environment. Anaerobes may be unicellular (e.g. protozoans,^[1] bacteria^[2]) or multicellular.^[3] Most fungi are obligate aerobes, requiring oxygen to survive. However, some species, such as the Chytridiomycota that reside in the rumen of cattle, are obligate anaerobes; for these species, anaerobic respiration is used because oxygen will disrupt their metabolism or kill them. Deep waters of the ocean are a common anoxic environment.^[3]

^ Upcroft P, Upcroft JA (January 2001). "Drug Targets and Mechanisms of Resistance in". Clin. Microbiol. Rev. 14 (1): 150–164. doi:10.1128/CMR.14.1.150-164.2001. PMC 88967. PMID 11148007.
^ Levinson, W. (2010). Review of Medical Microbiology and Immunology (11th ed.). McGraw-Hill. pp. 91–93. ISBN 978-0-07-174268-9.
^ ^a ^b Danovaro R; Dell'anno A; Pusceddu A; Gambi C; et al. (April 2010). "The first metazoa living in permanently anoxic conditions". BMC Biology. 8 (1): 30. doi:10.1186/1741-7007-8-30. PMC 2907586. PMID 20370908.

[pmc88967-1] Upcroft P, Upcroft JA (January 2001). "Drug Targets and Mechanisms of Resistance in". Clin. Microbiol. Rev. 14 (1): 150–164. doi:10.1128/CMR.14.1.150-164.2001. PMC 88967. PMID 11148007.

[Levinson,_W._2010_91–93-2] Levinson, W. (2010). Review of Medical Microbiology and Immunology (11th ed.). McGraw-Hill. pp. 91–93. ISBN 978-0-07-174268-9.

[pmid20370908-3] Danovaro R; Dell'anno A; Pusceddu A; Gambi C; et al. (April 2010). "The first metazoa living in permanently anoxic conditions". BMC Biology. 8 (1): 30. doi:10.1186/1741-7007-8-30. PMC 2907586. PMID 20370908.

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