ABSTRACT
Comparison has been proposed for the taxonomy of methanogens (subunit composition of the RNA polymerase, DNA-DNA hybridization, distribution and composition of polyamines, or lipids, antigenic cross-reactivity). It constitutes the framework for the taxonomy of methanogens based on evolutionary relationship. This chapter describes a simple taxonomic method based on the comparison of the apparent molecular weight of the three subunits of the methylreductase enzyme, also known as component C, the enzyme which catalyzes the last step of methane production. This technique consists of a quick one-step chromatographic enrichment of the methylreductase protein, followed by its purification to homogeneity using nondenaturing polyacrylamide gel electrophoresis. Several characteristics make the methylreductase protein particularly useful to identify methanogenic bacteria and determine their phylogenetic positions and relationships. This technique is especially useful in the case of methanogens isolated from marine environments.
