Thermogemmata fonticola gen. nov., sp. nov., the first thermophilic planctomycete of the order Gemmatales from a Kamchatka hot spring.

A novel aerobic moderately thermophilic bacterium, designated strain 2918T, was isolated from a terrestrial hot spring of Kamchatka, Russian Federation. Gram-negative, motile, spherical cells were present singly, in pairs, or aggregates, and reproduced by budding. The strain grew at 25-60°C and within a pH range of 5.0-8.0 with an optimum at 54-60°C and pH 7.5. Strain 2918T did not require sodium chloride or yeast extract for growth. It was a chemoorganoheterotroph, growing on mono-, di- and polysaccharides (starch, lichenan, galactan, arabinan, xanthan gum, beta-glucan). No growth was observed under anaerobic conditions neither in the presence of sulfur, nitrate, or thiosulfate nor without adding any electron acceptor. Major cellular fatty acids were C18:0 and C20:0. The respiratory quinone was MK-6. The size of the genome of strain 2918T was 4.81 Mb. Genomic DNA G+C content was 60.4mol%. According to the 16S rRNA gene sequence and conserved protein sequences phylogenies, strain 2918T represented a distinct lineage of the order Gemmatales within Planctomycetes. Based on phylogenetic analysis and phenotypic features, the novel isolate was assigned to a novel genus in the Gemmatales for which the name Thermogemmata gen. nov. is proposed. Strain 2918T (=KCTC 72012T =VKM B-3161T) represents its first species Thermogemmata fonticola sp. nov.