heterotrophe

Heterotrophe, more commonly referred to as a heterotroph in English, is an organism that cannot fix carbon dioxide to synthesize organic molecules. Instead, it relies on preformed organic compounds produced by other organisms to supply its carbon for growth. In most cases, heterotrophs also obtain energy from these organic compounds through respiration or fermentation.

Heterotrophs are contrasted with autotrophs, which can convert inorganic carbon, such as CO2, into organic matter. Within heterotrophs, two broad subtypes are often recognized: chemoheterotrophs, which derive both energy and carbon from chemical reactions involving organic substrates, and photoheterotrophs, which use light as an energy source while obtaining carbon from organic compounds.

Ecologically, heterotrophs include a wide range of organisms—animals, fungi, many bacteria, and some protists. They play essential roles as consumers, decomposers, and symbionts, driving nutrient cycles and energy flow in ecosystems. Some heterotrophs are specialists, feeding on living hosts (parasites), while others decompose dead organic matter (saprotrophs).

The term derives from Greek, with heteros meaning “other” and trophe meaning “nourishment.” While many organisms are strictly heterotrophic, some can exhibit mixotrophic strategies, switching between nutrition modes depending on environmental conditions.

In summary, heterotrophs obtain their carbon from organic sources produced by others and often rely on organic energy pathways, distinguishing them from autotrophs that fix inorganic carbon.