Mixotroph

A mixotroph is an organism that can use a mix of different sources of energy and carbon, instead of having a single trophic mode on the continuum from complete autotrophy at one end to heterotrophy at the other.

Possible combinations are photo- and chemotrophy, litho- and organotrophy, auto- and heterotrophy or other combinations of these. Mixotrophs can be either eukaryotic or prokaryotic.[1] They can take advantage of different environmental conditions.[2]

If a trophic mode is obligate, then it is always necessary for sustaining growth and maintenance; if facultative, it can be used as a supplemental source.[1] Some organisms have incomplete Calvin cycles, so they are incapable of fixing carbon dioxide and must use organic carbon sources.

Types of Mixotrophy

Organisms may employ mixotrophy obligately or facultatively.

In order to characterize the sub-domains within mixotrophy, several very similar categorization schemes have been suggested.

Consider the example of a marine protist with heterotrophic and photosynthetic capabilities: In the breakdown put forward by Jones,[4] there are four mixotrophic groups based on relative roles of phagotrophy and phototrophy.

An alternative scheme by Stoeker[5] also takes into account the role of nutrients and growth factors, and includes mixotrophs who have a photosynthetic symbiont or who retain chloroplasts from their prey. This scheme characterizes mixotrophs by their efficiency.

Examples

Plants

Amongst plants, mixotrophy classically applies to carnivorous, hemi-parasitic and partially hetero-mycotrophic species. However, this could be extended to a higher number of clades as research proves that organic forms of nitrogen and phosphorus such as DNA, proteins, amino-acids or carbohydrates also are part of a number of plants' nutrient supplies.[13]

See also

Notes

  1. 1 2 Eiler A (December 2006). "Evidence for the Ubiquity of Mixotrophic Bacteria in the Upper Ocean: Implications and Consequences". Appl Environ Microbiol 72 (12): 7431–7. doi:10.1128/AEM.01559-06. PMC 1694265. PMID 17028233.
  2. Katechakis A, Stibor H (July 2006). "The mixotroph Ochromonas tuberculata may invade and suppress specialist phago- and phototroph plankton communities depending on nutrient conditions". Oecologia 148 (4): 692–701. doi:10.1007/s00442-006-0413-4. PMID 16568278.
  3. Schoonhoven, Erwin (January 19, 2000). "Ecophysiology of Mixotrophs" (PDF). Thesis.
  4. Jones, H.J.L. (1997). "A classification of mixotrophic protists based on their behaviour". Freshwater Biology 37: 35-43.
  5. Stoecker, D.K. (1998). "Conceptual models of mixotrophy in planktonic protists and some ecological and evolutionary implications". European Journal of Protistology 34: 281-290.
  6. Tarangkoon, Woraporn (29 April 2010). "Mixtrophic Protists among Marine Ciliates and Dinoflagellates: Distribution, Physiology and Ecology" (PDF). Thesis.
  7. Libes, Susan M. (2009). Introduction to marine biogeochemistry (2 ed.). Academic Press. p. 192. ISBN 978-0-7637-5345-0.
  8. Dworkin, Martin (2006). The Prokaryotes: Ecophysiology and biochemistry 2 (3rd ed.). Springer. p. 988. ISBN 978-0-387-25492-0.
  9. Lengeler, Joseph W.; Drews, Gerhart; Schlegel, Hans Günter (1999). Biology of the Prokaryotes. Georg Thieme Verlag. p. 238. ISBN 978-3-13-108411-8.
  10. Bartosik D, Sochacka M, Baj J (July 2003). "Identification and Characterization of Transposable Elements of Paracoccus pantotrophus". J Bacteriol 185 (13): 3753–63. doi:10.1128/JB.185.13.3753-3763.2003. PMC 161580. PMID 12813068.
  11. Friedrich, Cornelius G.; et al. (2007). "Redox Control of Chemotrophic Sulfur Oxidation of Paracoccus pantotrophus". Microbial Sulfur Metabolism. Springer. pp. 139–150. PDF
  12. Fabricius, Katharina (2015). "Mixotrophy in soft corals of the Great Barrier Reef". http://data.aims.gov.au/. Australian Institute of Marine Science. Retrieved 11 November 2015. External link in |website= (help)
  13. Schmidt, Susanne; John A. Raven; Chanyarat Paungfoo-Lonhienne (2013). "The mixotrophic nature of photosynthetic plants". Functional Plant Biology 40 (5): 425. doi:10.1071/FP13061. ISSN 1445-4408. Retrieved 2013-11-26.

External links

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