Facultative anaerobic organism
A facultative anaerobic organism is an
Some examples of facultatively anaerobic bacteria are
It has been observed that in mutants of
There may exist a core network of transcription factors (TFs) that includes the major oxygen-responsive ArcA and FNR control the adaptation of Escherichia coli to changes in oxygen availability. Activities of these two regulators are indicative of spatial effects that may affect gene expression in the microaerobic range. It has also been observed that these oxygen-sensitive proteins are protected within the cytoplasm by oxygen consumers within the cell membrane, known as terminal oxidases.[10]
Functions
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.[11] For example, in the absence of oxygen, E. coli can use fumarate, nitrate, nitrite, dimethyl sulfoxide, or trimethylamine oxide as an electron acceptor.[11] This flexibility allows facultative anaerobes to survive in a number of environments, and in environments with frequently changing conditions.[1]
Several species of protists use a facultative anaerobic metabolism to enhance their ATP production, and some can produce dihydrogen through this process.[12]
As pathogens
Since facultative anaerobes are able to 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.[1]
The ability of facultative anaerobic pathogens to survive without oxygen is important since their infection is shown to reduce oxygen levels in their host's gut tissue.[13] 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.[1]
See also
- Aerobic respiration
- Anaerobic respiration
- Fermentation
- Obligate aerobe
- Obligate anaerobe
- Microaerophile
References
- ^ S2CID 233027658.
- ISBN 9780470016176.
- ISBN 0-8385-8529-9.
- ISBN 0-471-98880-4.
- ISBN 0-12-738446-4.
- ISSN 1616-1599. Retrieved February 14, 2010.
- ^ Yamamoto, N., & Droffner, M. L. (1985). Mechanisms determining aerobic or anaerobic growth in the facultative anaerobe Salmonella typhimurium. Proceedings of the National Academy of Sciences, 82(7), 2077-2081. https://doi.org/10.1073/pnas.82.7.2077
- core.ac.uk)
- ^ Pasteur L (1857). "Mémoire sur la fermentation applée lactique" [Dissertation on the fermentation called lactic]. Comptes rendus de l'Académie des Sciences (in French). 45 (913–916): 1032–1036.
- ^ Rolfe, M. D., Ocone, A., Stapleton, M. R., Hall, S., Trotter, E. W., Poole, R. K., ... & Green, J. (2012). Systems analysis of transcription factor activities in environments with stable and dynamic oxygen concentrations. Open biology, 2(7), 120091. https://doi.org/10.1098/rsob.120091
- ^ S2CID 33083164.
- PMID 21036663.
- PMID 26104016.