oxygentolerant

Oxygentolerant is an adjective used in biology to describe organisms or systems that can withstand exposure to molecular oxygen. In microbiology, the term is often used interchangeably with aerotolerant to denote microbes that do not require oxygen for growth but can survive in its presence, in contrast to obligate aerobes that require oxygen and obligate anaerobes that are harmed by it.

Oxygen tolerance is often due to enzymes that detoxify reactive oxygen species, such as superoxide dismutase, catalase, and peroxidases, as well as robust DNA repair and protective stress responses. These factors enable oxytolerant organisms to survive exposure to oxygen even if they do not use oxygen as a terminal electron acceptor.

In bacteria, common examples of aerotolerant (oxygentolerant) taxa include many lactic acid bacteria such as Streptococcus and Lactobacillus species; these organisms typically grow by fermentation in the absence of oxygen but withstand oxygen when it is present.

The concept is clinically and industrially relevant, affecting pathogenic potential, survival in oxygenated tissues, and product quality in fermentation and food processing. The term "oxygentolerant" is not as widely used as "aerotolerant" and is often considered a variant spelling; most literature uses aerotolerance terminology instead. See also aerotolerance, aerobic, anaerobic, facultative anaerobe.