RT Journal Article SR Electronic(1) A1 Ganzert, Lars A1 Schirmack, Janosch A1 Alawi, Mashal A1 Mangelsdorf, Kai A1 Sand, Wolfgang A1 Hillebrand-Voiculescu, Alexandra A1 Wagner, DirkYR 2014 T1 Methanosarcina spelaei sp. nov., a methanogenic archaeon isolated from a floating biofilm of a subsurface sulphurous lake JF International Journal of Systematic and Evolutionary Microbiology, VO 64 IS Pt_10 SP 3478 OP 3484 DO https://doi.org/10.1099/ijs.0.064956-0 PB Microbiology Society, SN 1466-5034, AB A novel methanogenic archaeon, strain MC-15T, was isolated from a floating biofilm on a sulphurous subsurface lake in Movile Cave (Mangalia, Romania). Cells were non-motile sarcina-like cocci with a diameter of 2–4 µm, occurring in aggregates. The strain was able to grow autotrophically on H2/CO2. Additionally, acetate, methanol, monomethylamine, dimethylamine and trimethylamine were utilized, but not formate or dimethyl sulfide. Trypticase peptone and yeast extract were not required for growth. Optimal growth was observed at 33 °C, pH 6.5 and a salt concentration of 0.05 M NaCl. The predominant membrane lipids of MC-15T were archaeol and hydroxyarchaeol phosphatidylethanolamine, phosphatidylglycerol, and phosphatidylinositol as well as hydroxyarchaeol phosphatidylserine and archaeol glycosaminyl phosphatidylinositol. The closely related species, Methanosarcina vacuolata and Methanosarcina horonobensis, had a similar composition of major membrane lipids to strain MC-15T. The 16S rRNA gene sequence of strain MC-15T was similar to those of Methanosarcina vacuolata DSM 1232T (sequence similarity 99.3 %), Methanosarcina horonobensis HB-1T (98.8 %), Methanosarcina barkeri DSM 800T (98.7 %) and Methanosarcina siciliae T4/MT (98.4 %). DNA–DNA hybridization revealed 43.3 % relatedness between strain MC-15T and Methanosarcina vacuolata DSM 1232T. The G+C content of the genomic DNA was 39.0 mol%. Based on physiological, phenotypic and genotypic differences, strain MC-15T represents a novel species of the genus Methanosarcina , for which the name Methanosarcina spelaei sp. nov. is proposed. The type strain is MC-15T ( = DSM 26047T = JCM 18469T)., UL https://www.microbiologyresearch.org/content/journal/ijsem/10.1099/ijs.0.064956-0