| Description | Allowable states are
aerobic
anaerobic
faculative anaerobic
microaerophilic
These assignments are based, in general, on observations reported in the literature rather than on genomic content. Aerobic means oxygen is both tolerated and required for growth. Anaerobic includes obligately anaerobic - oxygen must be absent to allow growth. Facultative anaerobic, sometime called facultative aerobic, means growth can occur without oxygen but can use (not simply avoid toxicity from) oxygen if available. Microaerophilic is used here to mean that some oxygen is required but that a low concentration is preferred. No state has been defined so far to cover obligate intracellular pathogens, for which it may not be possible to test oxygen requirements directly.
Note that characterization of oxygen requirements may reflect differences in interpretation and in experimental conditions. For example, an obligate aerobe found able to grow anaerobically with nitrate substituting for oxygen is reclassified as facultative anaerobic. |
