The methanogenic bacteria

Abstract

The methanogenic bacteria are a large and diverse group that is united by three features: (1) they are members of the domain Archaea, or archaebacteria (see Chap. 1), (2) they are strict anaerobes, and (3) they form large quantities of methane as the major product of their energy metabolism. The methanogenic bacteria are related to each other primarily by their mode of energy metabolism but are very diverse with respect to their other properties. Phylogenetically, the methanogens are members of the phylum Euryarchaota, in which they are classified into several classes, i.e., Methanobacteria, Methanococci and Methanomicrobia - each of which embraces several families and genera - as well as Methanopyri. A most updated phylogenetic tree based upon 16S rRNA gene sequences is provided in The All-Species Living Tree (Release LTPs115 from March 2014) (http://www.arb-silva.de/projects/living-tree/). The following text, focusing on metabolic properties, was originally published in The Prokaryotes, Third Edition.