Temperature regulation of anaerobic degradation of organic matter.

Anaerobic degradation of organic matter follows similar pathways in digesters and anaerobic freshwater sediments. The responsible microorganisms are linked in a complex food web, where short chain fatty acids and H2 are important intermediates. Degradation of short-chain fatty acids is endothermic under standard conditions and is only possible at low H2 partial pressures maintained by exothermic methanogenesis. The coupling between these endothermic and exothermic processes is delicate, and hence sensitive to environmental changes such as temperature variations. The effect of temperature on thermodynamics and on kinetics of these and other anaerobic degradation processes with emphasis on freshwater ecosystems is discussed.