Anaeroobses

The term anaeroobses does not appear in recognized biological nomenclature and is likely a misspelling of anaerobe or anaerobes. Anaerobes are organisms that do not require oxygen for growth; many are inhibited or killed by oxygen. They derive energy by fermentation or by anaerobic respiration using alternative electron acceptors such as nitrate, sulfate, or carbon dioxide.

Obligate or strict anaerobes cannot tolerate oxygen and must grow in oxygen-free environments. Facultative anaerobes can use oxygen when it is available but can switch to fermentation or anaerobic respiration in its absence. Aerotolerant anaerobes do not use oxygen but are not harmed by its presence. Microaerophiles require small amounts of oxygen and are not classified as anaerobes.

Oxygen exposure is toxic to many anaerobes because they lack or have low levels of detoxifying enzymes for reactive oxygen species. They often rely on fermentation to generate ATP, producing end products such as acids, alcohols, or gases, or they perform anaerobic respiration with alternative electron acceptors.

Habitats include the human gastrointestinal tract, oral cavity, soil, sediments, and anaerobic digesters. In industry and the environment, anaerobes drive fermentation and biodegradation and are employed in biogas production. In health, some anaerobes are commensals, while others, such as Clostridium and Bacteroides species, can cause opportunistic infections when displaced from their niches.

Cultivation requires oxygen-free handling, reducing media, and anaerobic chambers or jars.