kemotrofeja

Chemotrophy, sometimes rendered as kemotrofeja, is a metabolic strategy in which cells obtain energy by oxidizing chemical compounds. The energy released in redox reactions between an electron donor and an electron acceptor is captured mainly through oxidative phosphorylation to produce ATP. The carbon source of chemotrophs can be autotrophic (fixing CO2 into organic matter) or heterotrophic (relying on preformed organic compounds).

Chemotrophs are commonly divided by the nature of their electron donor: chemolithotrophs use inorganic substrates such as molecular hydrogen (H2), hydrogen sulfide (H2S), ammonia (NH3), nitrite (NO2−), or ferrous iron (Fe2+); chemoorganotrophs use organic molecules such as glucose, acetate, or alcohols. They are also categorized by their carbon metabolism: autotrophs fix carbon dioxide, whereas heterotrophs obtain carbon from organic matter.

The electron acceptor distinguishes aerobic from anaerobic chemotrophy. Aerobic chemotrophs use oxygen as the terminal electron acceptor; many chemolitho- and chemoorganotrophs can also respire anaerobically using alternatives such as nitrate, sulfate, ferric iron, or CO2 in various respiratory pathways. In environments lacking suitable electron acceptors, some chemotrophs may rely on fermentation-like processes, though these do not involve the same electron-transport chain.

Ecologically, chemotrophs play key roles in biogeochemical cycles, including those of nitrogen, sulfur, and carbon. They populate diverse habitats, from soils and oceans to hydrothermal vents, and include well-known bacteria such as Nitrosomonas (ammonia-oxidizing chemolithotrophs) and Thiobacillus (sulfur-oxidizing chemolithotrophs), as well as many chemoorganotrophs that decompose organic matter. Chemotrophy also has applications in wastewater treatment, bioremediation, and bioenergy.