Streptomyces secundicynarae sp. nov., a novel actinomycete isolated from the leaves of Cynara scolymus.

A novel actinobacterium strain, designated HUAS ZL42, was isolated from the leaves of Cynara scolymus. Its taxonomic position was characterized using a polyphasic method. Strain HUAS ZL42 produced spiral spore chains consisting of rod-shaped or ovoid spores with smooth surfaces on Gause's synthetic No.1 medium. The cell wall of strain HUAS ZL42 contained LL-diaminopimelic acid as a diagnostic amino acid. Whole-cell hydrolysates contained galactose and mannose. The predominant cellular fatty acids (>10.0%) of strain HUAS ZL42 were iso-C, anteiso-C and iso-C. The menaquinones were MK-9 (H), MK-9 (H) and MK-9 (H). The 16S rRNA gene sequence analysis showed that strain HUAS ZL42 exhibited the highest similarities to Streptomyces cyslabdanicus K04-0144 (98.6%), Streptomyces cinnabarigriseus JS360 (98.6%), Streptomyces cyaneus CGMCC 4.1671 (98.4%) and Streptomyces corchorusii DSM 40340 (98.4%). Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain HUAS ZL42 formed an independent subclade. Phylogenetic analysis based on five housekeeping gene sequences demonstrated that strain HUAS ZL42 was most closely related to S. cyaneus CGMCC 4.1671. However, the ANIm and dDDH between strain HUAS ZL42 and S. cyaneus CGMCC 4.1671 were 87.17% and 28.90%, respectively, far less than 96.7% and 70% cut-off points recommended for delineating Streptomyces species, suggesting that strain HUAS ZL42 was a novel Streptomyces species. On the basis of phenotypic and genotypic differentiation from tested strains, it is proposed that strain HUAS ZL42 represents a novel species of the genus Streptomyces, named Streptomyces secundicynarae sp. nov. The type strain is HUAS ZL42 (=MCCC 1K09444 = JCM 37325).