chemotrofe

Chemotrophs are organisms that obtain their energy by oxidizing chemical compounds rather than by capturing light energy. They derive energy from redox reactions that involve inorganic or organic substrates. Chemotrophy is one of the major energy-harvesting strategies in biology, distinct from phototrophy, in which light powers energy capture.

Chemotrophs are commonly divided into chemoorganotrophs, which use organic compounds as electron donors and energy sources, and chemolithotrophs, which use inorganic compounds such as ammonia, nitrite, hydrogen, reduced sulfur compounds, or ferrous iron. The electron acceptors used during oxidation can include oxygen (aerobic respiration) or alternative compounds such as nitrate, sulfate, or carbon dioxide in anaerobic processes.

Depending on their carbon source, chemotrophs may be autotrophic, fixing CO2 into biomass, or heterotrophic, using preformed organic carbon. Autotrophic chemotrophs often rely on inorganic energy sources and contribute to cycles such as nitrification or sulfur oxidation, while heterotrophic chemotrophs include many bacteria and fungi that consume organic molecules produced by other organisms.

Chemotrophs play crucial roles in ecosystems, particularly in environments lacking light, such as soil horizons, sediments, and deep-sea vents. They drive elemental cycles (carbon, nitrogen, sulfur) and support communities by forming primary production through chemolithoautotrophy or by consuming organic compounds produced by others.

Historically, chemotrophy was described after early microbial studies showing organisms obtaining energy from inorganic and organic chemical reactions. The term encompasses a broad set of metabolic strategies and contrasts with phototrophy and with different modes of metabolism.