Micromonospora solifontis sp. nov., an actinobacterium isolated from hot spring soil.

An actinobacterium strain, PPF5-17, was isolated from hot spring soil collected from Chiang Rai province, Thailand. The strain exhibited morphological and chemotaxonomic properties similar to those of members of the genus . Colonies of PPF5-17 were strong pinkish red and turned black after sporulation in ISP 2 agar medium. Cells formed single spores directly on the substrate mycelium. Growth was observed from 15 to 45 °C and at pH 5-8. Maximum NaCl concentration for growth was 3 % (w/v). PPF5-17 was found to have -diaminopimelic acid, xylose, mannose and glucose in the whole-cell hydrolysate. Diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol and phosphatidylinositolmannosides were observed as the membrane phospholipids. MK-10(H), MK-9(H), MK-10(H) and MK-9(H) were the major menaquinones. The predominant cellular fatty acids were iso-C, iso-C, anteiso-C and iso-C. PPF5-17 shared the highest 16S rRNA gene sequence similarity with LMG 30467 (99.3 %). A genome-based taxonomic study revealed that PPF5-17 was closely related to DSM 44815 in the phylogenomic tree with an average nucleotide identity by blast (ANIb) of 87.7 % and a digital DNA-DNA hybridization (dDDH) value of, 36.1 % which were below the threshold values for delineation of a novel species. Moreover, PPF5-17 could be distinguished from its closest neighbours, LMG 30467 and DSM 44815, with respect to a broad range of phenotypic properties. Thus, PPF5-17 represents a novel species, for which the name sp. nov. is proposed. The type strain is PPF5-17 (= TBRC 8478 = NBRC 113441).