organotrofi

Organotrophy is a metabolic strategy in which organisms obtain electrons from organic compounds. It is a subset of chemotrophy, distinguished from lithotrophy, where electrons are derived from inorganic substrates such as hydrogen, reduced minerals, or simple inorganic compounds. In organotrophy, energy can be harvested either by respiration, using external electron acceptors (for example oxygen, nitrate, or sulfate), or by fermentation, in which organic substrates serve as both electron donors and internal electron acceptors.

Organotrophs may be aerobic or anaerobic. In aerobic organotrophs, organic substrates are oxidized with an external electron acceptor like O2, producing carbon dioxide and water. In anaerobic organotrophs, alternative electron acceptors such as nitrate or sulfate are used. Fermentative organotrophs derive energy through substrate-level phosphorylation and redox balancing without external electron acceptors, yielding end products such as organic acids, alcohols, or gases.

Organisms that exhibit organotrophy include many bacteria and fungi. Common examples are heterotrophic bacteria such as Escherichia coli and yeasts such as Saccharomyces cerevisiae, which metabolize a variety of organic substrates including sugars, amino acids, and organic acids. In broader usage, organotrophy is sometimes treated synonymously with chemoorganotrophy, though some texts differentiate the terms by emphasizing the organic electron donor source versus the overall energetic strategy.

Organotrophy is a fundamental concept in microbiology and biogeochemistry, helping to classify organisms by how they obtain energy and reducing equivalents from organic matter and how they contribute to the cycling of carbon in ecosystems.