Streptomyces polaris sp. nov. and Streptomyces septentrionalis sp. nov., isolated from frozen soil.

Two novel actinomycetes, designated strains ZLN81 and ZLN712, were isolated from a frozen soil sample which was collected from the Arctic region. Chemotaxonomic and morphological characteristics were found to be typical of members of the genus Streptomyces. Based on 16S rRNA gene sequence analyses, the two strains show high similarity with Streptomyces polygonati NEAU-G9 (99.45%, 99.17%) and Streptomyces yanglinensis 1307 (98.17%, 98.10%). DNA-DNA relatedness between each of the strains and their close phylogenetic neighbours showed that they belonged to distinct species. Multilocus sequence analysis (MLSA) using four housekeeping genes (atpD, gyrB, recA and rpoB) for comparing Streptomyces type strains showed that the MLSA distance of strains ZLN81 and ZLN712 to the closely related species was greater than the 0.007 threshold. The cell wall amino acids of the two strains were identified as alanine, glycine, asparagine, ll-diaminopimelic acid and meso-diaminopimelic acid. The whole cell sugars were identified as galactose and glucose for strain ZLN81 and galactose, glucose and xylose for strain ZLN712. The predominant menaquinones were identified as MK-10(H), MK-9(H) and MK-9(H) for strain ZLN81 and MK-9(H), MK-10(H) and MK-9(H) for strain ZLN712. The polar lipid profile of strain ZLN81 was found to contain diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, phosphatidylinositol mannosides and two unidentified phospholipids, while that of strain ZLN712 consisted of diphosphatidylglycerol, phosphatidylethanolamine, a ninhydrin-positive glycophospholipid, phosphatidylinositol mannosides and two unidentified phospholipids. The major fatty acids were identified as iso-C, anteiso-C, C and anteiso-C for strain ZLN81 and iso-C, C, anteiso-C and iso-C for strain ZLN712. The DNA G+C contents were found to be 73.96 and 72.77 mol% for strains ZLN81 and ZLN712, respectively. On the basis of these phenotypic and genotypic data, strains ZLN81 (= CCTCC AA 2018010 = DSM 107255) and ZLN712 (= CCTCC AA 2018011 = DSM 107266) are concluded to represent two novel species of the genus Streptomyces, for which the names Streptomyces polaris sp. nov. and Streptomyces septentrionalis sp. nov. are proposed, respectively.