Primary nutritional groups

Primary nutritional groups are groups of organisms, divided in relation to the nutrition mode according to the sources of energy and carbon, needed for living, growth and reproduction. The sources of energy can be light or chemical compounds; the sources of carbon can be of organic or inorganic origin.

The terms aerobic respiration, anaerobic respiration and fermentation (substrate-level phosphorylation) do not refer to primary nutritional groups, but simply reflect the different use of possible electron acceptors in particular organisms, such as O₂ in aerobic respiration, or nitrate (NO⁻
₃), sulfate (SO²⁻
₄) or fumarate in anaerobic respiration, or various metabolic intermediates in fermentation.