Facultative anaerobic organism

Facultative anaerobes are able to grow in both the presence and absence of oxygen due to the expression of both aerobic and anaerobic respiratory chains using either oxygen or an alternative electron acceptor. For example, in the absence of oxygen, E. coli can use fumarate, nitrate, nitrite, dimethyl sulfoxide, or trimethylamine oxide as an electron acceptor. == As pathogens ==

Since facultative anaerobes can grow in both the presence and absence of oxygen, they can survive in many different environments, adapt easily to changing conditions, and thus have a selective advantage over other bacteria. As a result, most life-threatening pathogens are facultative anaerobes. Moreover, the ability of facultative anaerobes to limit oxygen levels at infection sites is beneficial to them and other bacteria, as dioxygen can form reactive oxygen species (ROS). These species are toxic to bacteria and can damage their DNA, among other constituents. == See also ==