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

Abstract

A novel aerotolerant anaerobic bacterium (strain M4AhT) 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 M4AhT tolerated 2% oxygen in the gas phase, was catalase-positive, and showed sustainable growth under microaerobic conditions. The dominant cellular fatty acids of strain M4AhT were C16:0 and C18:0. The G+C content of the genomic DNA was 32.42%. The closest phylogenetic relative of strain M4AhT was Mariniplasma anaerobium from the family Acholeplasmataceae (order Acholeplasmatales, class Mollicutes). Based on the polyphasic characterization of the isolate, strain M4AhT 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 M4AhT (=DSM 112561T = VKM B-3485T = UQM 41475T). This is the first representative of the order Acholeplasmatales, isolated from a mud volcano.