This term describes the metabolic processes
in anaerobic life forms that generate ATP by a process that depends on
a chemiosmotic mechanism where the ultimate electron acceptor is not oxygen.
The reduced product of the electron transport chain is therefore not water.
Methanogens in the reticulo-rumen use part of the carbon dioxide that they
take up from the growth environment for this purpose; the product of its
reduction is methane. Other organisms can use fumarate reductase
for ATP production by anaerobic respiration. Fumarate is reduced
by NADH to succinate in a redox cycle which achieves charge separation
across a membrane and ATP synthesis is driven by dissipation of the energy
inherent in the electrochemical ion gradient.