autotrof

An autotroph, sometimes written as autotrof, is an organism that can synthesize organic compounds from inorganic sources, typically using carbon dioxide as the carbon source. Autotrophs obtain energy either from light (photoautotrophs) or from chemical reactions involving inorganic substances (chemoautotrophs).

Photoautotrophs use light energy to drive the synthesis of organic molecules from CO2, a process that also releases oxygen in oxygenic photosynthesis. This group includes plants, algae, and cyanobacteria, and it forms the base of many ecosystems by providing organic matter and energy for other organisms.

Chemoautotrophs derive energy from redox reactions involving inorganic substances, such as the oxidation of ammonia, nitrite, sulfur compounds, or ferrous iron. They fix CO2 through pathways like the reverse Krebs cycle or the Calvin cycle and are common in environments where light is unavailable or scarce, such as deep-sea vents and subsurface soils. Chemoautotrophs are represented by various bacteria and archaea.

Autotrophs play a central ecological role as primary producers, converting inorganic carbon into organic matter that fuels food webs and contributes to global carbon cycling and oxygen production. They are contrasted with heterotrophs, which require preformed organic carbon from other organisms for growth.

In some contexts, the term encompasses both photo- and chemoautotrophs; in others, autotrophy may be discussed alongside mixotrophy, where organisms can switch between autotrophic and heterotrophic modes depending on conditions.