Mixotrophy

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Mixotrophy (from Greek mixis = mixture and Trophos = nourishing) is a term for the ability of some organisms to both carbon dioxide assimilate as also from organic feed materials. They are thus neither completely autotrophic nor completely heterotrophic ; So they can carry out photosynthesis or chemosynthesis , as well as absorb and digest food particles (or whole organisms) ( phagotrophy ) or dissolved substances ( osmotrophy ) from other organisms .

Range of nutritional strategies

The carbon obtained from the opposing diets autotrophy and heterotrophy can be very variable; for example, there are species which obtain more carbon from autotrophy than from heterotrophy and, in contrast, species which obtain more carbon from heterotrophy. Mixotrophy is therefore not absolute, but there is a continuous spectrum from absolute auto- to absolute heterotrophy.

Benefits of mixotrophy

Mixotrophy gives the organisms greater flexibility in their diet. Photosynthetically active organisms can gain access to nutrients that they would otherwise not have been able to use through the additional ingestion of food particles ( phagotrophy ) or dissolved substances ( osmotrophy ). Primarily heterotrophic organisms with the ability to carry out photosynthesis can thus grow and reproduce even in times of low food density.

Classes of Mixotrophy

According to A. Mitra (2019), the following four classes of mixotrophy can be distinguished:

  1. Constitutive mixotrophy (the predator is capable of photosynthesis itself)
  2. non-constitutive mixotrophy - generalists
  3. non-constitutive mixotrophy - cell organelle specialists
  4. non-constitutive mixotrophy - endosymbiosis specialists

(Classes 2 and 3 fall under the generic term Kleptoplastidie ).

Examples

Mixotrophic organisms, all of which are planktonic unicellular organisms, are found in water bodies in particular . Examples are Euglena , Paramecium bursaria and some types of algae (various golden algae , some Chlamydomonas species, Pfiesteria shumwayae ). Recently it has also been possible for higher plants, e.g. B. forest orchids of the genera Cephalanthera and Epipactis , a mixotrophic diet with the help of mushrooms can be demonstrated.

See also

literature

Individual evidence

  1. ^ A. Mitra (2019), p. 57