More Than 200 Genes Required for Methane Formation from H2and CO2and Energy Conservation Are Present inMethanothermobacter marburgensisandMethanothermobacter thermautotrophicus

The hydrogenotrophic methanogens Methanothermobacter marburgensis and Methanothermobacter thermautotrophicus can easily be mass cultured. They have therefore been used almost exclusively to study the biochemistry of methanogenesis from H 2 and CO 2 , and the genomes of these two model organisms have been sequenced. The close relationship of the two organisms is reflected in their genomic architecture and coding potential. Within the 1,607 protein coding sequences (CDS) in common, we identified approximately 200 CDS required for the synthesis of the enzymes, coenzymes, and prosthetic groups involved in CO 2 reduction to methane and in coupling this process with the phosphorylation of ADP. Approximately 20 additional genes, such as those for the biosynthesis of F 430 and methanofuran and for the posttranslational modifications of the two methyl-coenzyme M reductases, remain to be identified.