A Methanogenic Archaeon from Ace Lake, Antarctica: Methanococcoides burtonii sp. nov.

A methylotrophic, methanogenic bacterium was isolated from the anoxic hypolimnion of Ace Lake, Antarctica, a lake with ionic composition similar to that of seawater. The new isolate utilized methanol in addition to methylamines but not H2:CO2, formate or acetate. The optimum and maximum temperatures for growth were 23.4 and 29.5 °C respectively. The strain grew in artificial media at in situ lake temperature (1.7°C), provided growth was first initiated in the media at higher temperatures. The strain had a theoretical minimum temperature for growth of -2.5 °C. The mol% G+C content of DNA from the strain was 39.6% (Tm). The phenotype, polar lipid pattern, antigenic fingerprint and 16S rRNA sequence of the strain were most similar to, but distinct from Methanococcoides methylutens. DNA/DNA homology was low between the Ace Lake methanogen and Methanococcoides methylutens (27.5%). A new species Methanococcoides burtonii is described and the type strain is DSM 6242.