Microbes and Methanogenesis

In oxygen-free environments, specialized archaea called methanogens carry out methanogenesis, producing methane as the end product of their energy metabolism.

Organic compounds from dead organisms often sink into anoxic zones, where cellulolytic bacteria break them down into simple sugars.

Fermentative microbes convert these sugars into short-chain fatty acids, such as acetate, alcohols, hydrogen, and carbon dioxide.

Methanogens can directly consume acetate and hydrogen and convert them into methane. By consuming hydrogen, methanogens keep hydrogen levels low, allowing fermentation to continue.

Syntrophic bacteria help in the breakdown of alcohols and other fatty acids by converting them into acetate, hydrogen, and carbon dioxide.

Methanogens then use these compounds to produce methane.

Similarly, in the termite gut, microbes break down cellulose into sugars. Anoxic protists ferment these into hydrogen, which endosymbiotic methanogens consume. This keeps hydrogen levels low, enabling ongoing fermentation and acetate production that termites absorb for energy.