Describe differences that would be seen in the growth curve of a facultative anaerobe that is grown in the presence of oxygen, and the same facultative anaerobe grown in the absence of oxygen.

Facultative anaerobes are able to grow in the presence or absence of oxygen. When oxygen is present, oxygen serves as the final electron acceptor in electron transport. ATP yield is relatively high. When oxygen is absent, facultative anaerobes rely on alternative final electron acceptors or on fermentation to produce ATP. ATP yield is relatively low. Because growth rate is to some degree dependent on ATP production, growth rate will be faster in the presence of oxygen than in its absence. Consequently, if growth curves were constructed for the facultative anaerobe growing in the presence or absence of oxygen, the lag phase would be longer and the log phase would be less steep when oxygen is not present.