A Gram-stain-positive, aerobic actinobacterial strain designated MMS17-BM035T isolated from mountain soil around a decaying tree was subjected to taxonomic characterization. The isolate developed extensively branched substrate mycelia and white aerial hyphae on International Streptomyces Project 2 agar. Strain MMS17-BM035T grew at 15-34 °C (optimum, 30 °C), at pH 5.0-8.0 (optimum, pH 7.0) and in the presence of 0-6 % NaCl (optimum, 0 %). Analysis of 16S rRNA gene sequences indicated that MMS17-BM035T fell into a phylogenetic cluster belonging to the genus Streptomyces. MMS17-BM035T shared the highest sequence similarity of 99.45 % with Streptomyces fuscigenes JBL-20T, and no higher than 98.7 % with other species of Streptomyces. Based on the orthologous average nucleotide identity, MMS17-BM035T was again mostly related to S. fuscigenes JBL-20T with 84.14 % identity, and less than 80 % with other species. The digital DNA-DNA hybridization analysis also indicated low levels of relatedness with related species, as the highest value was observed with S. fuscigenes JBL-20T (28.8 %). The major fatty acids of the strain were anteiso-C15 : 0, a summed feature (consisting of C18 : 1 ω7c/C18 : 1 ω6c), iso-C15 : 0, C16 : 0 and C20 : 0. The major respiratory quinones were MK-9(H4) and MK-9(H6). The diagnostic polar lipids were diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylinositolmannoside. The major cell-wall diamino acid was ll-diaminopimelic acid, and the characteristic whole-cell sugars were glucose and ribose. The DNA G+C content was 72.1 mol%. Strain MMS17-BM035T exhibited antimicrobial activity against several Gram-positive bacteria and yeasts. Based on both phenotypic and phylogenetic evidences, strain MMS17-BM035T should be classified as representing a novel species, for which the name Streptomyces montanisoli sp. nov. (type strain=MMS17-BM035T=KCTC 49544T=JCM 34528T) is proposed.
Keywords: Streptomyces montanisoli; antimicrobial activity; decaying tree soil.