A novel Gram-stain-positive, aerobic actinobacterial strain designated NR30T was isolated from riverside soil. A polyphasic approach was employed for the taxonomic characterization of NR30T. The strain developed extensively branched light brown to light pink substrate mycelia and light grey aerial mycelia, and produced spiny spores in loose spiral spore chains on ISP 3 and 4 agars. NR30T grew at 10-40°C (optimum, 30°C), at pH 6.0-9.0 (optimum, pH 8.0) and in the presence of 0-3 % NaCl (optimum, 0 %). Analysis of 16S rRNA gene sequences indicated that NR30T represents a member of the genus Streptomyces. NR30T shared the highest 16S rRNA gene sequence similarity with Streptomyces cyaneus NRRL B-2296T (98.6 %). On the basis of orthologous average nucleotide identity, NR30T was most closely related to Streptomyces panaciradicis NBRC 109811T with 86.3 % identity. The results of the digital DNA-DNA hybridization analysis also indicated low levels of relatedness with other species, as the highest value was observed with Streptomyces panaciradicis NBRC 109811T (31.1 %). The major fatty acids of the strain were anteiso-C15 : 0, C16 : 0, iso-C16 : 0 and anteiso-C17 : 0. The major respiratory quinones were MK-9(H8) and MK-9(H6). The diagnostic polar lipids were diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylinositol mannoside. The major cell wall diamino acid was ll-diaminopimelic acid, and the characteristic whole-cell sugars were rhamnose, ribose and glucose. The DNA G+C content was 70.3 mol %. NR30T exhibited antimicrobial activity against several Gram-negative bacteria and yeasts. On the basis of the results of both phenotypic and phylogenetic analyses, strain NR30T evidently represents a novel species of the genus Streptomyces, and the name Streptomyces guryensis sp. nov. (type strain=NR30T =KCTC 49653T=LMG 32476T) is proposed accordingly.
Keywords: Streptomyces guryensis; antimicrobial activity; riverside soil.