Anaerobic organism

An anaerobic organism is any organism that does not require oxygen for growth. Obligate anaerobes will die when exposed to atmospheric levels of oxygen.Facultative anaerobes can use oxygen when it is present. Aerotolerant organisms can survive in the presence of oxygen, but they are anaerobic because they do not use oxygen as a terminal electron acceptor.
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An organism that does not need oxygen to stay alive. See anaerobic.