chemoorganotrophs

Chemoorganotrophs are organisms that obtain energy by oxidizing organic compounds and use those same compounds as electron donors. They derive carbon primarily from organic matter, and most chemoorganotrophs are heterotrophs.

Metabolism among chemoorganotrophs ranges from respiration to fermentation. In respiration, they transfer electrons through an electron transport chain to a terminal acceptor such as oxygen, nitrate, sulfate, or ferric iron, generating ATP by oxidative phosphorylation. In fermentation, they obtain energy through substrate-level phosphorylation without a final inorganic electron acceptor. Consequently, chemoorganotrophs can be aerobic, anaerobic, or facultatively anaerobic, and they span a wide range of environmental niches.

Examples and ecological roles of chemoorganotrophs are diverse. Bacteria such as Escherichia coli, Bacillus subtilis, and Pseudomonas species are classic chemoorganotrophs. In eukaryotes, many fungi (for example, Saccharomyces cerevisiae) are chemoorganotrophs that consume organic carbon and can grow fermentatively or respiratorily depending on conditions. Chemoorganotrophs play essential roles in decomposition and nutrient cycling, breaking down organic matter and contributing to carbon, nitrogen, and sulfur turnover in ecosystems. They also include many organisms of medical and industrial importance, ranging from human pathogens to organisms used in fermentation and biotechnology.

Chemoorganotrophs are contrasted with chemolithotrophs, which obtain energy from the oxidation of inorganic electron donors, and with phototrophs, which harvest energy from light.