Cell envelopes of methanogens

Abstract

Methanogens play an important role in the global carbon cycle, because they are involved in the last step of anaerobic degradation of organic material to methane. Although the first report on methane emanation from aquatic muds was given by Alessandro Volta in the year 1776, the first methanogen was not obtained in pure culture before 1947. Special culture techniques had to be developed for growing the strict anaerobic methanogenic isolates. The methanogens were the first species of the archaeal domain (Archaea) detected. Their unique biochemical and genetic properties have stimulated basic investigations of this microbial group in the last three decades. The methanogenic Archaea possess a remarkable diversity of cell envelope types, which support the novel phylogenetic concept based on rRNA sequence analysis. The chemical composition and structure of their cell wall layers differs significantly from those of the bacterial domain (Bacteria). They are composed of different polymers such as pseudomurein, S-layer, methanochondroitin and proteinaceaous sheaths, which are described here. © 2010 Springer-Verlag Berlin Heidelberg.