Methanococcus jannaschii sp. nov., an extremely thermophilic methanogen from a submarine hydrothermal vent

Abstract

A new extremely thermophilic methane-producing bacterium was isolated from a submarine hydrothermal vent sample collected by a research team from the Woods Hole Oceanographic Institution using the manned submersible ALVIN. The sample was obtained from the base of a “white smoker” chimney on the East Pacific Rise at 20° 50′ N latitude and 109° 06′ W longitude at a depth of 2600 m. The isolate was a motile irregular coccus with an osmotically fragile cell wall and a complex flagellar system. In defined medium with 80% H₂ and 20% CO₂, the isolate had a doubling time of 26 min at 85° C. The pH range for growth was 5.2 to 7.0 with an optimum near 6.0. NaCl was required for growth with an optimum of 2 to 3% (w/v). The mol % G+C was 31%. In cell-free extracts, methane formation from methylcoenzyme M was temperature-dependent, and H₂ or formate served as electron donors. Methane formation from H₂ and CO₂ occurred at a much lower rate. Oligonucleotide cataloging of the 16S ribosomal RNA established the isolate as a new species of the genus Methanococcus and the name Methanococcus jannaschii is proposed. The isolation of M. jannaschii from a submarine hydrothermal vent provides additional evidence for biogenic production of CH₄ from these deep-sea environments.