The family methanopyraceae

Abstract

The family Methanopyraceae currently consists of a single genus with a single species: Methanopyrus kandleri. It is a rod-shaped chemolithoautotrophic methanogenic archaeon that grows optimally at 98 °C and grows up to 110 °C and possibly higher under high hydrostatic pressure, making it the most extreme thermophile among the methanogens. No growth is observed below 84 °C. Strains of M. kandleri were isolated from marine hydrothermal vent systems. The organism contains 2,3-di-O-phytanyl-sn-glycerol and 2,3-di-O-geranylgeranyl-sn-glycerol lipids. In 16S rRNA phylogenetic trees, it forms a very deep branch near the root of the Archaea, remote from the other lineages of methanogens. However, in trees based on concatenated alignments of ribosomal proteins or proteins involved in transcription, M. kandleri consistently groups with other methanogens, suggesting that the methanogens are a monophyletic group of Archaea.