Depiction of the proton gradient force generated by the electron transport chain.
Most chemoautotrophs are lithotrophs, using inorganic electron donors such as hydrogen sulfide, hydrogen gas, elemental sulfur, ammonium and ferrous oxide as reducing agents and hydrogen sources for biosynthesis and chemical energy release. Chemolithoautotrophs are microorganisms that synthesize energy through the oxidation of inorganic compounds.[1] 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 the ATP produced during photosynthesis or the oxidation of chemical compounds to reduce NADP+ to NADPH to form organic compounds.[2] 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.
Generation of ATP using the proton gradient force.
Chemolithoautotrophs are microbes that derive energy from the oxidation of inorganic compounds. They fix atmospheric CO₂ as their sole carbon source. Unlike photoautotrophs, they do not use light (but rather chemical energy). Through oxidative phosphorylation, they use a proton gradient force to generate the production of adenosine triphosphate (ATP), which is the primary energy source of living organisms. In order to fix CO₂, they reverse the electron transport chain using electron donors with high redox potentials.[3][2][4]
Chemolithoautotrophs add nutrients through nitrification (ammonia to nitrate), sulfur oxidation (hydrogen sulfide to sulfate), and iron oxidation. This metabolic activity fertilizes soil, affects water quality, and atmospheric composition.[5][6] They inhabit extreme environments such as deep-sea thermal vents, acidic hot springs, and underground.[5] In hydrothermal vents, they are the base of the food web.[7][8][9] Taxa such as aquificae, sulfurimonas, and nitratifactor dominate microbial communities within water samples, fauna, and rocks, respectively.[10]
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