Streptomyces citrinus sp. nov., with yellow diffusible pigment

An actinomycete, designated strain Q6^T, was isolated from tea plant rhizosphere soil sample in Hefei, China. Strain Q6^T produced straight chains of smooth-surfaced spores and grew well on International <i>Streptomyces</i> Project 1-7 media. Phenotypic and genotypic analyses indicated that strain Q6^T represented a member of the genus <i>Streptomyces</i>. The 16S rRNA gene sequence data of strain Q6^T indicated that strain Q6^T had the highest sequence similarity to <i>Streptomyces xanthii</i> CRXT-Y-14^T (98.9%), <i>Streptomyces davaonensis</i> JCM 4913^T (98.9%) and <i>Streptomyces atriruber</i> NRRL B-24165^T (98.9%), followed by <i>Streptomyces adustus</i> WH-9^T (98.8%), <i>Streptomyces avermitilis</i> MA-4680^T (98.6%) and <i>Streptomyces kunmingensis</i> NBRC 14463^T (98.6%). The phylogenomic tree, using the genome blast distance phylogeny method, showed that strain Q6^T represents a new branch among the <i>Streptomyces</i> and has the closest genetic relationship with <i>S. kunmingensis</i> 80-3024^T. The diagnostic diamino acid was ll-diaminopimelic acid. The major menaquinones were MK-9 (H₆), MK-9 (H₈) and MK-8 (H₆). The dominant fatty acids were C_{16 : 0} (18.6%), iso-C_{16 : 0} (18.3%), anteiso-C_{15 : 0} (15.4%) and summed feature 3 (C_{16 : 1} <i> ω</i>7c and/or C_{16 : 1} <i> ω</i>6c; 13.8%). The main polar lipids were diphosphatidylglycerol, phosphatidylinositol, phosphatidylethanolamine (PE) and phosphatidylinositol mannoside. The DNA G+C content of strain Q6^T was 71.3 mol%. Average nucleotide identity and digital DNA-DNA hybridization values between the genome sequence of strain Q6^T and its closely related type strains were 77.0-87.5% and 22.4-29.7%, respectively. On the basis of these data, strain Q6^T represents a novel species within the genus <i>Streptomyces</i>, for which the name <i>Streptomyces citrinus</i> sp. nov. is proposed. The type strain is strain Q6^T (=CGMCC 4.7886^T=NBRC 116061^T).