chemolithoheterotroph

A chemolithoheterotroph is an organism that derives its energy from the oxidation of inorganic compounds (chemolithotrophy) while obtaining its carbon from organic sources (heterotrophy). In these organisms, inorganic substrates such as molecular hydrogen (H2), reduced sulfur compounds (sulfide, thiosulfate), ferrous iron (Fe2+), or reduced nitrogen compounds can drive energy-yielding metabolism, often through respiration with oxygen or alternative electron acceptors like nitrate.

The carbon skeletons used for growth come from organic compounds, such as sugars, amino acids, or organic acids, rather than from CO2 fixation. This combination places chemolithoheterotrophs in a distinct metabolic niche, different from chemolithoautotrophs, which fix CO2, and from chemoorganoheterotrophs, which derive both energy and carbon from organic substrates.

Ecology and occurrence: chemolithoheterotrophs have been described in a limited subset of bacteria and archaea. They are typically found in environments where inorganic energy sources are available but organic carbon is present in limited or specialized forms, such as certain sediments, subsurface habitats, or extreme environments. Their metabolic strategy can provide resilience in fluctuating nutrient conditions by coupling inorganic energy generation with organic carbon assimilation.

Relation to other metabolisms: the term emphasizes a specific combination of energy and carbon sources and highlights metabolic diversity among prokaryotes. It denotes a niche rather than a single taxonomic group, reflecting the modular nature of microbial metabolism.