| Description | Organisms which exhibit optimal growth in the presence of oxygen, but are inhibited by it in amounts approaching atmospheric levels (or saturating levels in aqueous environments). The precise definitions of this category are difficult to establish, and organisms considered to fall within this category may have differring relationships to the utilization of and protection from oxygen. Certain organisms may benefit from extremely low levels of oxygen (facultative microaerophiles) but are perfectly viable under anaerobic conditions. Others may require small amounts of oxygen but be unable to grow anaerobically (obligate microaerophiles). Organsisms which grow markedly better under anaerobic conditions but can survive low oxygen tensions are rather referred to as aerotolerant anaerobes and are categorized under anaerobes. |
