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^T) 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^T possessed an ability to degrade extraneous DNA. Major cellular fatty acids were C_16:0 and i-C_17:0; major dimethyl acetals were C_14:0 DMA and i-C_15:0 DMA. The genome of strain C05PYG^T 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^T 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^T to a novel species of a novel genus, Liberiplasma polymorphum gen. nov., sp. nov.; the type strain is C05PYG^T (=VKM B-3767^T = BIM B-2060^T = UQM 41800^T). This genus is placed in a novel family, Liberiplasmataceae fam. nov. within the novel order Liberiplasmatales ord. nov., class Mollicutes.