Question

Explain the concept of chemolithotrophy. How do cells derive energy? How do cells derive cellular carbon? Where do the electrons come from? Please provide an example(including microbe Genus species name). (please list references used)

Answer 1

The chemolithoautotrophs are the organisms that depend on inorganic chemicals as the source energy and electrons. The chemolithotrophs use the inorganic compounds as the electron donors. These compounds are oxidized and the electrons are transported into electron transport chains (ETC) to synthesize ATP by chemiosmosis. The electron acceptor can be oxygen in aerobic bacteria, but a variety of other inorganic electron acceptors are also used by various species. The species like Desulfosarcina and Desulfonema are chemolithoautotrophs that use H2 as electron donor and sulfate (SO42-) as an electron acceptor and CO2 as sole carbon source.

The sulfur oxidizing chemolithotrophs oxidize the inorganic compounds like reduced sulfur compounds like H2S, elemental sulfur (S0), thiosulfate or thiocyanate and use as electron donors. The Thiobacillus belongs to the betaproteobacteria and is widely studied sulfur chemolithotrophs. The Thiobacillus oxidizes H2S, S0 or thiosulfate to sulfuric acid (H2SO4) and thus Thiobacilli are acidophilic. These organisms convert CO2 in to carbohydrates by Calvin cycle.