Autotrofien

Autotrofien, or autotrophs, are organisms that synthesize organic compounds from inorganic carbon sources. They obtain energy either from light (photoautotrophs) or from the oxidation of inorganic molecules (chemoautotrophs). Autotrofien form the base of many ecosystems by converting inorganic carbon into biomass that can be used by other organisms.

Photoautotrophs include plants, algae, and cyanobacteria; they capture light energy through photosynthesis to fix carbon dioxide into sugars. Chemoautotrophs include certain bacteria and archaea, such as nitrifying bacteria, sulfur-oxidizing bacteria, and iron-oxidizers, which derive energy from chemical reactions involving inorganic substrates.

In most autotrophs, carbon fixation converts inorganic CO2 into organic molecules. Several pathways exist, including the Calvin-Benson-Bassham cycle in plants and most bacteria, the reverse TCA cycle in some bacteria and archaea, and other specialized cycles in diverse lineages. Oxygen is produced in oxygenic photoautotrophs as a byproduct.

Ecologically, autotrophs are primary producers that support food webs and drive biogeochemical cycles, such as the carbon and oxygen cycles. They occupy a range of habitats, from terrestrial forests and freshwater to marine environments and deep-sea vents.

Autotrophs differ from heterotrophs, which rely on preformed organic carbon. While most photoautotrophs require light, some chemoautotrophs flourish in dark or extreme environments. Understanding autotrophy helps explain the foundations of ecosystems and the history of life on Earth.