Methanosarcina baltica, sp nov., a novel methanogen isolated from the Gotland Deep of the Baltic Sea

A novel methanogen, Methanosarcina baltica GS1-A(T), DSM 14042, JCM 11281, was isolated from sediment at a depth of 241 m in the Gotland Deep of the Baltic Sea. Cells were irregular, monopolar monotrichous flagellated cocci 1.5-3 mum in diameter often occurring in pairs or tetrads. The catabolic substrates used included methanol, methylated amines, and acetate, but not formate or H2CO2. Growth was observed in a temperature range between 4degrees and 27degreesC with an optimum at 25degreesC. The doubling time with methanol as substrate was 84 h at 25degreesC, 120 h at 9degreesC, and 167 h at 4degreesC. The doubling time with acetate as substrate was 252 h at 25degreesC and 425 h at 20degreesC. After the transfer of methanol-grown cultures, long lag phases were observed that lasted 15-20 days at 25degreesC and 25 days at 4degrees-9degreesC. The NaCl optimum for growth was 2%-4%, and the fastest growth occurred within a pH range of 6.5-7.5. Analysis of the 16S rDNA sequence revealed that the strain was phylogenetically related to Methanosarcina. The sequence similarity to described species of <95.7% and its physiological properties distinguished strain GS1-A(T) from all described species of the genus Methanosarcina.