Peloplasma aerotolerans gen. nov., sp. nov., a Novel Anaerobic Free-Living Mollicute Isolated from a Terrestrial Mud Volcano.

A novel aerotolerant anaerobic bacterium (strain M4Ah T ) was isolated from a terrestrial mud volcano (Taman Peninsula, Russia). Cells were small, cell-wall-less, non-motile cocci, 0.32-0.65 μm in diameter. The isolate was a mesophilic, neutrophilic chemoorganoheterotroph, growing on carbohydrates (D-glucose, D-trehalose, D-ribose, D-mannose, D-xylose, D-maltose, D-lactose, D-cellobiose, D-galactose, D-fructose, and D-sucrose), proteinaceous compounds (yeast extract, tryptone), and pyruvate. Strain M4Ah T tolerated 2% oxygen in the gas phase, was catalase-positive, and showed sustainable growth under microaerobic conditions. The dominant cellular fatty acids of strain M4Ah T were C 16:0 and C 18:0 . The G+C content of the genomic DNA was 32.42%. The closest phylogenetic relative of strain M4Ah T was Mariniplasma anaerobium from the family Acholeplasmataceae (order Acholeplasmatales , class Mollicutes ). Based on the polyphasic characterization of the isolate, strain M4Ah T is considered to represent a novel species of a new genus, for which the name Peloplasma aerotolerans gen. nov., sp. nov. is proposed. The type strain of Peloplasma aerotolerans is M4Ah T (=DSM 112561 T = VKM B-3485 T = UQM 41475 T ). This is the first representative of the order Acholeplasmatales , isolated from a mud volcano.