Streptomyces fuscus sp. nov., a brown-black pigment producing actinomycete isolated from dry mudflat sand

A novel Gram-stain-positive, aerobic actinobacterial strain, designated GXMU-J15 T , was isolated from dry mudflat sand. A polyphasic approach was employed for its taxonomic characterization. The strain developed extensively branched yellowish white to light yellow substrate mycelia and white aerial mycelia, and produced smooth cylindrical spores in a loose straight spore chain on International Streptomyces Project 2–7 agar media. Strain GXMU-J15 T grew at 20–50 °C (optimum, 35 °C), at pH 5.0–8.0 (optimum, pH 7.0) and in the presence of 0–8 % (w/v) NaCl. Analysis of 16S rRNA gene sequences indicated that strain GXMU-J15 T represents a member of the genus Streptomyces . Strain GXMU-J15 T showed the highest 16S rRNA gene sequence similarity to Streptomyces lusitanus CGMCC 4.1745 T (99.1 %) and Streptomyces thermocarboxydus CGMCC 4.1883 T (98.8 %). Phylogenetic tree analysis based on multilocus sequence analysis (MLSA) and whole genome sequence construction revealed that strain GXMU-J15 T was most closely related to Streptomyces cupreus PSKA01 T , Streptomyces cinnabarinus DSM 40467 T and Streptomyces davaonensis JCM 4913 T . The MLSA and genome-to-genome distances between strain GXMU-J15 T and its relatives were 0.0418, 0.0443 and 0.0485 and 0.1237, 0.1188 and 0.1179, respectively. The results of orthologous average nucleotide identity and digital DNA–DNA hybridization analysis corroborated the results of the MLSA and whole genome sequence evolution analysis, indicating that the novel isolate represents a distinct species of the genus Streptomyces . The whole-cell sugars of strain GXMU-J15 T were xylose, glucose and galactose. The characteristic diamino acid in the cell-wall hydrolysate was ll -diaminopimelic acid. The lipids contained diphosphatidylglycerol, phosphatidylmethylethanolamine, phosphatidylethanolamine, phosphatidylinositol, phosphatidylglycerol, phosphatidylglycerides, phosphatidylcholine, two phospholipids of an unknown structure containing glucosamine, one unknown phospholipid and two unknown lipids. The major cellular fatty acid components were iso-C 15 : 0 , anteiso-C 15 : 0 , iso-C 16 : 0 and anteiso-C 17 : 0 . The main respiratory quinone types were MK-9(H6) and MK-9(H8). The whole genome size of strain GXMU-J15 T was 8.68 Mbp, with 71.23 mol% G+C content. Genomic analysis indicated that strain GXMU-J15 T has the potential to synthesize polyketides, terpenes and a series of important antibiotics besides the gene cluster for melanin synthesis. Based on these genotypic and phenotypic data, strain GXMU-J15 T is proposed to represent a new species of the genus Streptomyces named Streptomyces fuscus sp. nov. The type strain is GXMU-J15 T (=MCCC 1K08211 T =JCM 35917 T ).