Isoptericola croceus sp. nov., a novel actinobacterium isolated from saline-alkali soil.

A novel actinomycete, designated strain q2, was isolated from the saline-alkaline soil, collected from Daqing, Heilongjiang province, China. The results of phylogenetic analysis based on the 16S rRNA gene sequences indicated that strain q2 belongs to the genus Isoptericola, and showed the highest sequence similarity to Isoptericola halotolerans KCTC 19046 (98.48%) and Isoptericola chiayiensis KCTC 19740 (98.13%), respectively. The average nucleotide identity values between strain q2 and other members of the genus Isoptericola were lower than 95% recommended for distinguishing novel prokaryotic species. Cells of strain q2 were Gram-staining-positive, aerobic, non-motile, rod-shaped and non-spore-forming. Colonies of strain q2 were golden-yellow pigmented, tidy edged and smooth surfaced. Growth occurred at 15-37 °C (optimum, 29 °C), pH 7.0-10.0 (optimum, pH 8.0). The predominant respiratory quinones were MK-9(H) and MK-9(H). The main detected polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, and phosphatidylinositol mannoside. The peptidoglycan compositions were L-alanine, D-aspartic, L-glutamic acid and L-lysine (type A4α). The major cellular fatty acids (> 10%) were anteiso-C, iso-C, and anteiso-C. The G+C content of the genomic DNA was determined to be 69.7%. Based on the phenotypic, physiological, genotypic, and phylogenetic data, strain q2 represents a novel species of the genus Isoptericola, for which the name Isoptericola croceus sp. nov. is proposed. The type strain is q2 (= GDMCC 1.2923 = KCTC 49759).