Liberiplasma polymorphum gen. nov., sp. nov., a novel cell-wall-less free-living anaerobe, isolated from a terrestrial mud volcano, and proposal of Liberiplasmataceae fam. nov. and Liberiplasmatales ord. nov.

A novel anaerobic free-living bacterium (strain C05PYG) was isolated from a terrestrial mud volcano (Taman Peninsula, Russia). Cells were pleomorphic but mainly consisted of small, cell wall-less, non-motile cocci, 0.40-0.46 μm in diameter. The temperature range for growth was 5-37 °C (optimum at 30 °C). The pH range for growth was 7.5-10.0, with an optimum at pH 8.0-9.0. It was a chemoorganoheterotroph, fermenting mono-, di- and polysaccharides (dextrin, starch), proteinaceous substrates and organic acids (lactate and pyruvate). Yeast extract was essential for growth. Strain C05PYG possessed an ability to degrade extraneous DNA. Major cellular fatty acids were C and i-C; major dimethyl acetals were C DMA and i-C DMA. The genome of strain C05PYG had a size of 2.0 Mb with a DNA G + C content of 33.0 % (WGS). Phylogenetic analysis based on 120 marker genes placed strain C05PYG in a separate order adjacent to the order Acholeplasmatales within the class Mollicutes, hitherto referred to as "Izemoplasmatales", which contains no representatives with validly published names. We propose to assign strain C05PYG to a novel species of a novel genus, Liberiplasma polymorphum gen. nov., sp. nov.; the type strain is C05PYG (=VKM B-3767 = BIM B-2060 = UQM 41800). This genus is placed in a novel family, Liberiplasmataceae fam. nov. within the novel order Liberiplasmatales ord. nov., class Mollicutes.