Streptomyces aquilus sp. nov., a novel actinomycete isolated from a Chinese medicinal plant

Abstract

The taxonomic position of a novel actinomycete isolate, designated strain GGCR-6^T, isolated from the healthy leaves of <i>Xanthium sibiricum</i> collected from the botanic garden of Hunan University of Science and Technology in Hunan province, PR China, was determined by a polyphasic approach. GGCR-6^T grew well on ISP series media and formed well-developed, branched substrate hyphae and aerial mycelium that differentiated into straight spore chains consisting of cylindrical spores with smooth surfaces. The diagnostic diamino acid was ll-diaminopimelic acid. The major menaquinones were MK-9(H₈), MK-9(H₂), MK-9 and MK-9(H₆). The polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphotidylinositol and phosphatidylinositol mannosides. The predominant fatty acids were C_{16 : 1}ω9<i>c</i>, iso-C_{16 : 0} and C_{16 : 0}. The phenotypic characteristics of GGCR-6^T indicated that it represented a member of the genus <i>Streptomyces</i>. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that GGCR-6^T was most closely related to <i>Streptomyces cyaneus</i> NRRL B2296^T and <i>Streptomyces griseoruber</i> NRRL B1818^T. However, the digital DNA-DNA hybridization, the average nucleotide identity and the multi locus sequence analysis evolutionary distance clearly separate GGCR-6^T from the phylogenetically closely related species. Furthermore, the novel isolate was distinctly differentiated from <i>S. cyaneus</i> NRRL B2296^T and <i>S. griseoruber</i> NRRL B1818^T by morphological, physiological and biochemical characteristics. Based on these data, strain GGCR-6^T should be designated as a representative of a novel species of the genus <i>Streptomyces</i>, for which the name <i>Streptomyces aquilus</i> sp. nov. is proposed. The type strain is strain GGCR-6^T (=CICC 11055^T=JCM 33584^T).