Airtolerant

Airtolerant, often written aerotolerant in biological literature, refers to organisms that can tolerate the presence of oxygen but do not require it for growth. These organisms are not obligate aerobes, which need oxygen, nor obligate anaerobes, which are harmed by oxygen. Instead, they can grow in either aerobic or anaerobic environments, typically relying on fermentation or other anaerobic metabolic pathways for energy.

In terms of metabolism, air-tolerant organisms do not use oxygen as the terminal electron acceptor. Their survival in oxygen-rich conditions is aided by cellular defenses against reactive oxygen species, such as enzymes that detoxify byproducts of oxygen exposure. This allows them to persist in environments where oxygen is present without performing aerobic respiration.

Growth characteristics of airtolerant organisms are generally robust across a range of oxygen levels, though some populations may show modest differences in growth rate or yield depending on the environment. They are often associated with fermentation-based lifestyles and can play important roles in natural ecosystems as well as industrial processes.

Ecologically, airtolerant bacteria are found in various niches, including the human microbiome and food fermentation ecosystems. They can contribute to food production, preservation, and flavor development, and may act as neutral or beneficial members of microbial communities. While they are adaptable to oxygen exposure, their metabolic strategies do not capitalize on aerobic respiration.

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