Chemolithotrophy

Chemolithotrophy is a mode of metabolism that obtains energy by oxidizing inorganic compounds. It occurs in diverse microorganisms, often supporting growth where organic food is scarce.

Electron transport chain: A series of membrane-associated reactions that transfers electrons and helps generate a proton gradient for ATP synthesis. Chemolithotrophs pass electrons from inorganic donors through these chains to conserve energy.
Lithotrophy: A metabolic strategy that uses reduced inorganic compounds as electron donors. Chemolithotrophy is the energy-conserving form of this broader donor-based category.
Nitrification: The microbial oxidation of ammonia to nitrite and then nitrate. Nitrifying microbes gain energy by oxidizing reduced inorganic nitrogen compounds.
Chemosynthesis: The production of organic matter using energy from chemical reactions rather than sunlight. Chemolithotrophy can provide the energy that powers chemosynthetic biomass production.
Oxidative phosphorylation: ATP production driven by electron transport and the resulting electrochemical gradient across a membrane. It converts energy from donor oxidation into ATP in many chemolithotrophs.
Chemoautotrophy: A metabolism that obtains energy from chemical reactions and uses carbon dioxide or other inorganic carbon as its carbon source. It combines chemical energy with inorganic carbon assimilation, a common chemolithotrophic pattern.
Sulfur oxidation: The oxidation of reduced sulfur compounds, such as hydrogen sulfide, elemental sulfur, or thiosulfate. Sulfur-oxidizing microorganisms use these inorganic compounds as energy sources.
Autotrophy: A mode of nutrition in which organisms build organic matter from inorganic carbon sources. Many chemolithotrophs are autotrophs, although the terms describe different metabolic dimensions.
Chemiosmosis: The movement of ions down an electrochemical gradient through a membrane protein, coupled to cellular work. Ion gradients produced during inorganic-compound oxidation can power ATP synthesis.
Chemoheterotrophy: A metabolism that obtains energy from chemical compounds and carbon from organic compounds. It contrasts with chemolithotrophic growth on inorganic electron donors.

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