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Achemolithoautotroph is an organism that that uses inorganic chemical compounds to source its energy and electrons, and use carbon dioxide as a carbon source.[1] They do not require organic compounds or light.
Mostchemoautotrophs arelithotrophs, using inorganic electron donors such as hydrogen sulfide,hydrogen gas, elementalsulfur,ammonium andferrous oxide as reducing agents and hydrogen sources forbiosynthesis and chemical energy release. Chemolithoautotrophs aremicroorganisms that synthesize energy through the oxidation of inorganic compounds.[2] They can sustain themselves entirely on atmospheric CO₂ and inorganic chemicals without the need for light or organic compounds. They enzymatically catalyze redox reactions using mineral substrates to generate ATP energy. Autotrophs use a portion of theATP produced during photosynthesis or the oxidation of chemical compounds to reduceNADP+ to NADPH to form organic compounds.[3] These substrates primarily include hydrogen, iron, nitrogen, and sulfur. Its ecological niche is specialized to deep marine hydrothermal vents, stratified sediment, and subsurface rock. Their metabolic processes play a key role in supporting microbial food webs as primary producers, and biogeochemical fluxes.
Chemolithoautotrophs are microbes that derive energy from the oxidation of inorganic compounds. They fix atmospheric CO₂ as their sole carbon source. Unlikephotoautotrophs, they do not use light (but rather chemical energy). Throughoxidative phosphorylation, they use a proton gradient force to generate the production ofadenosine triphosphate (ATP), which is the primary energy source of living organisms. In order to fix CO₂, they reverse theelectron transport chain using electron donors with high redox potentials.[4][3][5]
Chemolithoautotrophs add nutrients throughnitrification (ammonia to nitrate), sulfur oxidation (hydrogen sulfide to sulfate), and iron oxidation. This metabolic activity fertilizes soil, affects water quality, and atmospheric composition.[6][7] They inhabit extreme environments such as deep-seathermal vents, acidic hot springs, and underground.[6] In hydrothermal vents, they are the base of the food web.[8][9][10] Taxa such as aquificae, sulfurimonas, and nitratifactor dominate microbial communities within water samples, fauna, and rocks, respectively.[11]