Fontivita pretiosa gen. nov., sp. nov., a thermophilic planctomycete of the order Tepidisphaerales from a hot spring of Baikal lake region.

A novel facultatively anaerobic moderately thermophilic bacterium, strain B-254, was isolated from a terrestrial hot spring near the town of Goryachinsk in the Baikal lake region (Russian Federation). Motile spherical cells of the strain were present as single cocci, in pairs, or aggregates. The cells had a Gram negative cell wall and reproduced by binary fission. The isolate grew at 30-57 °C (opt. 50-54 °C) and at pH 5.1-8.4 (opt. 6.6-7.1). Strain B-254 was a chemoorganoheterotroph, growing on mono-, di- and polysaccharides (xylan, starch, galactan, galactomannan, xyloglucan, arabinan, curdlan, beta-glucan, locust bean gum, xanthan gum). Sodium chloride or yeast extract were not required for growth. Major cellular fatty acids were iso-C, anteiso-C, and C; major polar lipid was phosphatidylethanolamine. The complete genome of strain B-254 was 5.54 Mb; its GC content was 64 %. According to the results of 16S rRNA gene sequence-based phylogenetic analysis and the conserved proteins sequences-based phylogenomic analysis strain B-254 was on a separate lineage within the order Tepidisphaerales (Phycisphaerae, Planctomycetes). Based on phylogenetic and phylogenomic analyses of Phycisphaerae, whole genome comparisons of Tepidisphaerales as well as distinctive phenotypic features of the strain, it was assigned to a novel genus and species for which the name Fontivita pretiosa gen. nov. sp. nov. is proposed. Strain B-254 = KCTC 82380 = VKM B-3507.