Streptomyces ureilyticus sp. nov. and Streptomyces mesophilus sp. nov., two novel Actinobacteria with antimicrobial activity isolated from lake sediment

Two novel Actinobacteria, designated strains YC419^T and YC504^T, were isolated from a sediment sample collected from Lake Yeniçağa, Bolu Province, Turkey. Chemotaxonomic and morphological characteristics of isolates were found to be typical of members of the genus Streptomyces. Phylogenetic analyses based on 16S rRNA gene sequences revealed that strain YC419^T was most closely related to Streptomyces vastus NBRC 13094^T (99.0 %) and 'Streptomyces xiangluensis' NEAU-LA29 (98.6 %), and strain YC504^T was to most closely related to Streptomyces caldifontis NCCP-1331^T (98.6 %) and Streptomyces indicus IH32-1^T (98.0 %). The cell walls of the two strains contained ll-diaminopimelic acid as the diagnostic diamino acid and the whole-cell hydrolysates were glucose, mannose and ribose. The predominant menaquinones were MK-9(H₈) and MK-9(H₆) in both strains. The major polar lipids of strain YC419^T were diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylinositol, while strain YC504^T had a similar profile but lacking diphosphatidylglycerol. The G+C contents of the genomic DNAs were 69.6 and 70.3 mol% for strains YC419^T and YC504^T, respectively. The phenotypic and genotypic data indicated that these two strains were readily distinguished from one another and the type strains of the other species classified in the genus Streptomyces. Therefore, the strains are suggested to represent two novel species of the genus Streptomyces, for which the names Streptomyces ureilyticus sp. nov. and Streptomyces mesophilus sp. nov. are proposed. The type strains are YC419^T (=DSM 102299^T=KCTC 39757^T) and YC504^T (=DSM 102300^T=KCTC 39756^T), respectively.