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 2918(T), 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 degrees C and within a pH range of 5.0-8.0 with an optimum at 54-60 degrees C and pH 7.5. Strain 2918(T) did not require sodium chloride or yeast extract for growth. It was a chemoorganoheterotroph, growing on mono-, diand 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 C-18:0 and C-20:0. The respiratory quinone was MK-6. The size of the genome of strain 2918(T) was 4.81 Mb. Genomic DNA G + C content was 60.4 mol%. According to the 16S rRNA gene sequence and conserved protein sequences phylogenies, strain 2918(T) 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 2918(T) (=KCTC 72012(T) =VKM B-3161(T)) represents its first species Thermogemmata fonticola sp. nov. (C) 2020 Elsevier GmbH. All rights reserved.