Autotrofy

Autotrofy is a term used in some languages to refer to autotrophs, organisms that synthesize organic matter from inorganic carbon sources such as CO2 or bicarbonate. Autotrophs sustain themselves without needing preformed organic nutrients, and they form the base of most ecosystems by providing biomass for other organisms. They are contrasted with heterotrophs, which obtain carbon by consuming existing organic compounds.

There are two main groups of autotrophs. Photoautotrophs use light energy to drive carbon fixation; common examples include plants, algae, and cyanobacteria. Chemoautotrophs obtain energy by oxidizing inorganic substances (such as ammonia, nitrite, sulfide, or ferrous iron) and fix carbon without light. Chemoautotrophs are especially important in environments without sunlight, such as deep-sea hydrothermal vents and some soils and sediments.

Most photoautotrophs fix carbon via the Calvin cycle, while chemoautotrophs employ alternative pathways such as the reverse Krebs cycle or hydroxypropionate cycle. Autotrophy enables life to exploit inorganic energy sources and to fix CO2, contributing to global carbon cycling and biomass production.

Ecologically, autotrophs are primary producers that convert inorganic carbon into organic matter, supporting food webs and, in the case of oxygenic photoautotrophs, releasing oxygen. Evolutionarily, autotrophic metabolism arose early in Earth's history, with oxygenic photosynthesis by cyanobacteria playing a major role in shaping the atmosphere and climate.