aerotolerant

Aerotolerant refers to organisms that can survive in the presence of oxygen but do not use oxygen for growth or energy. These organisms do not require oxygen for metabolism and are not inhibited by it in the same way as obligate anaerobes; they can grow in both aerobic and anaerobic environments.

Physiologically, aerotolerant organisms typically rely on fermentation or other anaerobic pathways for energy production. They may possess enzymes that detoxify reactive oxygen species, such as catalase or superoxide dismutase, which helps them withstand oxygen exposure without engaging in oxidative respiration.

They are distinct from facultative and obligate aerobes. Facultative anaerobes can switch between respiration in the presence of oxygen and fermentation in its absence, often growing more rapidly when oxygen is available. Aerotolerant organisms, by contrast, do not gain an energy advantage from oxygen and do not exploit aerobic respiration.

Common examples and habitats include lactic acid bacteria such as Streptococcus and Lactobacillus species. These organisms are found in the human mouth and gastrointestinal tract, in dairy products, and in various plant-associated environments. They play roles in fermentation, food preservation, and maintaining microbial communities in oxygen-containing niches.

See also: aerobe, anaerobe, facultative anaerobe, microaerophile.