Partners jointly carry out a metabolism that is energetically or chemically unavailable to either partner alone under the same conditions.
Operational definition
Metabolic-cooperation category.
A form of metabolic cooperation in which the combined activities of two or more organisms make a transformation thermodynamically or chemically possible under conditions where the participants could not independently complete it at a viable rate.
A common mechanism is the rapid removal of an intermediate—such as hydrogen or formate—so that the producing partner’s reaction remains energetically favorable.
For this taxonomy, syntrophy should be used in this relatively strict energetic sense rather than as a synonym for all cross-feeding.