Chemoorganotroph

Chemoorganotroph is a term used in microbiology to describe organisms that obtain energy by oxidizing organic compounds. The carbon source is typically organic, so most chemoorganotrophs are heterotrophs. These organisms harvest chemical energy through various metabolic strategies to support growth and maintenance.

Energy generation occurs mainly through respiration or fermentation. In respiration, organic substrates donate electrons to an electron transport chain, with a terminal electron acceptor such as oxygen, nitrate, sulfate, or ferric iron. In fermentation, energy is produced without external electron acceptors, yielding smaller amounts of ATP through substrate-level phosphorylation and partial oxidation of the organic substrate.

Chemoorganotrophs are widespread in soils, oceans, sediments, and host-associated microbiomes. They play essential roles in decomposition and nutrient cycling, helping to recycle carbon and other elements. They are also important in food production and biotechnology, including fermentation processes. Common examples include bacteria such as Escherichia coli, Bacillus subtilis, and Streptococcus species, as well as the yeast Saccharomyces cerevisiae.

Chemoorganotrophy is one branch of chemotrophy. It is distinguished from chemolithotrophy, where energy is derived from the oxidation of inorganic compounds, and from phototrophy, where energy is captured from light. Many organisms can switch between metabolic modes (for example, respiration and fermentation) in response to environmental conditions such as oxygen availability.