Methylomonas scandinavica sp nov., a new methanotrophic psychrotrophic bacterium isolated from deep igneous rock ground water of Sweden

Methane-utilizing bacteria were enriched from deep igneous rock environment s and affiliated by amplification of functional and phylogenetic gene probe s. Type I methanotrophs belonging to the genera Methylomonas and Methylobac ter dominated in enrichment cultures from depths below 400 m. A pure cultur e of an obligate methanotroph (strain SR5) was isolated and characterized. Pink-pigmented motile rods of the new isolate contained intracytoplasmic me mbranes as stacks of vesicles, assimilated methane via the ribulose monopho sphate pathway and had an incomplete tricarboxylic acid cycle. Phosphatidyl glycerol, methylene ubiquinone and cytochrome c(552) were prevailing. The DNA G+C content is 53.3 mol %. Strain SRS grew at temperatures between 5 an d 30 degrees C with optimum at 15 degrees C, close to its in situ temperatu re. Analyses of 16S rRNA gene, whole cell protein, enzymatic and physiologi cal analyses of strain SR-5 revealed significant differences compared to th e other representatives of Type I methanotrophs. Based on pheno- and genoty pic characteristics we propose to refer the strain SR5 as to a new species, Methylomonas scandinavica.