Streptomyces macrolidinus sp. nov., a novel soil actinobacterium with potential anticancer and antimalarial activity.

A novel actinomycete, strain RY43-2, belonging to the genus , was isolated from a peat swamp forest soil collected from Rayong Province, Thailand. The strain was characterized by using a polyphasic approach. The cell-wall peptidoglycan contained ll-diaminopimelic. Ribose and glucose were detected in its whole-cell hydrolysates. The strain contained anteiso-C, iso-C and iso-C as the predominant fatty acids, and MK-9(H), MK-9(H) and MK-9(H) as the major menaquinones. The phospholipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannoside, three unidentified ninhydrin-positive phospholipids and two unidentified phospholipids. Strain RY43-2 showed the highest 16S rRNA gene similarity to JCM 4497 (98.9 %) and LCR6-01 (98.9 %). The draft genome of RY43-2 was 6.7 Mb with 6078 coding sequences with an average G+C content of 70.8 mol%. Genomic analysis revealed that the average nucleotide identity (ANI) values based on blast (ANIb) and MUMmer (ANIm) between strain RY43-2 and JCM 4497 were 80.1 and 86.1%, respectively. The ANIb and ANIm values between strain RY43-2 and LCR6-01 were 77.0 and 85.5%, respectively. The digital DNA-DNA hybridization values were 25.2 and 23.0% in comparison with the draft genomes of JCM 4497 and LCR6-01, respectively. The results of taxonomic analysis suggested that strain RY43-2 represented a novel species of the genus for which the name sp. nov. is proposed. The type strain is RY43-2 (=TBRC 7286=NBRC 115640). Strain RY43-2 exhibited antimicrobial activity against ATCC 51559, BMGC 106 and BMGC 107 with the minimum inhibitory concentration values of 25.0, 12.5, and 6.25 µg ml. It also exhibited potent antimalarial activity against K1 with IC of 0.0031 µg ml. In addition, it showed cytotoxicity against Vero, KB, MCF-7 and NCI-H187 with IC values of 0.0347, 6.15, 3.36 and 0.0352 µg ml, respectively.