Serinibacter arcticus sp. nov., isolated from a thawing ancient ice wedge

A novel actinobacterium, strain K3-2^T, was isolated in pure culture from a thawing ancient ice wedge at Mammoth Mountain (Eastern Siberia, Russia). Colonies of strain K3-2^T were yellowish orange; cells had the fine structure typical of Gram-positive bacteria, were non-motile short rods and were non-spore-forming. Strain K3-2^T was mesophilic (optimum growth at 28 °С), but capable of growing at 4 °С. The cell-wall peptidoglycan of strain K3-2^T contained lysine (the diagnostic diamino acid), glutamic acid, alanine, ornithine, glycine and serine. The polar lipids were phosphatidylglycerol, lysophosphatidylserine, three unidentified phospholipids and glycolipids. The major fatty acids were anteiso-C_15 : 0 and C_16 : 0. The only menaquinone detected was MK-8(H₄). 16S rRNA gene analysis indicated that strain K3-2^T belongs to the genus Serinibacter. The closest taxonomically described relatives were Serinibacter salmoneus Kis4-28^T and Serinibacter tropicus PS-14-7^T, with 97.20 and 97.20 % 16 s rRNA gene sequence similarity, respectively. The average nucleotide identity value of the whole genome sequence between strain K3-2^T and S. salmoneus Kis4-28^T was 78.9 %. DNA-DNA relatedness values between strain K3-2^T and S. salmoneus DSM 21801^T (=Kis4-28^T) and S. tropicus VKPM Ac 2044^T (=PS-14-7^T) were 41 and 47 %. Thus, strain K3-2^T represents a novel species of the genus Serinibacter for which the name Serinibacter arcticus sp. nov. is proposed. The type strain is K3-2^T (DSM 103859^T=VKM Ас-2719^T).