Streptomyces spirodelae sp. nov., isolated from duckweed.

A novel actinobacterium, designated strain DW4-2T, was isolated from duckweed (Spirodela sp.) collected from an agricultural pond in Kasetsart University, Bangkok, Thailand. The morphological, chemotaxonomic and phylogenetic characteristics were consistent with its classification in the genus Streptomyces. Strain DW4-2T showed the highest 16S rRNA gene sequence similarity values to Streptomyces qinglanensis DSM 42035T (98.5 %), Streptomyces smyrnaeus DSM 42105T (98.4 %) and Streptomyces oryzae S16-07T (98.4 %). Digital DNA-DNA hydridization and average nucleotide identity values between the genome sequences of strain DW4-2T with S. qinglanensis DSM 42035T (29.8 and 87.8 %), S. smyrnaeus DSM 42105T (33.1 and 89.0 %) and S. oryzae S16-07T (33.0 and 88.9 %) were below the thresholds of 70 and 95-96 % for prokaryotic conspecific assignation. Chemotaxonomic data revealed that strain DW4-2T possessed MK-9(H6) and MK-9(H8) as the predominant menaquinones. It contained ll -diaminopimelic acid as the diagnostic diamino acid and glucose, ribose and trace amount of madurose in whole-cell sugars. The polar lipids consisted of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, phosphatidylinositol mannoside, an unidentified aminolipid, an unidentified lipid and an unidentified phospholipid. The predominant cellular fatty acids were anteiso-C17 : 0, anteiso-C15 : 0 and iso-C16 : 0. The genomic DNA size of the strain DW4-2T was 7 310 765 bp with DNA G+C content 71.0 mol%. Genomic analysis of the genome indicated that the strain DW4-2T had the potential to produce bioactive compounds. On the basis of these genotypic and phenotypic data, it is supported that strain DW4-2T represents a novel species of the genus Streptomyces, for which the name Streptomyces spirodelae sp. nov. is proposed. The type strain is strain DW4-2T (=TBRC 13095T=NBRC 114803T).