Granulicella sibirica sp. nov., a psychrotolerant acidobacterium isolated from an organic soil layer in forested tundra, West Siberia

An isolate of strictly aerobic, pale-pink pigmented bacteria, strain AF10(T) , was obtained from an organic soil layer in forested tundra, Nadym region, West Siberia. Cells of strain AF10(T) were Gram-negative, non-motile rods that produced an amorphous extracellular polysaccharide-like substance and formed large cell aggregates in old cultures. These bacteria were chemoorganotrophic, mildly acidophilic and psychrotolerant, and grew between pH 3.5 and 7.0 (optimum, pH 4.5-5.0) and at temperatures between 2 and 30 degrees C. The preferred growth substrates were sugars and some polysaccharides. The major fatty acids were iso-C-15:(0), C-16(:0), C-16(:)1 Delta 9 c and 13,16-dimethyl octacosanedioic acid. The genome of strain AF10(T) was 6.14 Mbp in size and encoded a wide repertoire of carbohydrate active enzymes. The genomic DNA G+C content was 59.8 mol%. Phylogenetic analysis indicated that strain AF10(T) is a member of the genus Granulicella, family Acidobacteriaceae, but displays 94.4-98.0 % 16S rRNA gene sequence similarity to currently described members of this genus. On the basis of phenotypic, chemotaxonomic, phylogenetic and genomic analyses, we propose to classify this bacterium as representing a novel species of the genus Granulicella, Granulicella sibirica sp. nov. Strain AF10(T) (=DSM 104461(T) =VKM B-3276(T)) is the type strain.