Streptomyces gobiensis sp. nov., an antimicrobial producing actinobacterium isolated from soil under black Gobi rocks

A novel actinomycete, strain 1_25T, was isolated from soil under a black Gobi rock sample from Shuangta, PR China, and characterized using a polyphasic taxonomic approach. The results of comparative analysis of the 16S rRNA gene sequences indicated the 1_25T represented a member of the genus Streptomyces . Chemotaxonomic data revealed that 1_25T possessed MK-9(H8) as the major menaquinone. The cell wall contained ll-diaminopimelic acid (ll-DAP) and the whole-cell sugar pattern consisted of ribose, glucose and galactose. Major fatty acid methyl esters were observed to be iso-C16 : 0 (23.6 %), and anteiso-C15 : 0 (10.4 %). The genomic DNA G+C content of 1_25T was 69 mol %. The results of phylogenetic analysis based on 16S rRNA gene sequence indicated that 1_25T had high sequence similarity with Streptomyces qinglanensis 172205T (98.1 %), Streptomyces lycii TRM 66187T (98 %), and Streptomyces griseocarneus JCM4580T (98 %). In addition to the differences in phenotypic characters, the average nucleotide identity (ANI) and digital DNA–DNA hybridization (dDDH) values between 1_25T and closely related species were below the recommended threshold values for assigning strains to the same species. The fermentation product of 1_25T in ISP2 had an inhibitory effect on Staphylococcus aureus . On the basis of these genotypic and phenotypic characteristics, strain 1_25T (=JCM 34936T=GDMCC 4.216T) represents a novel species of the genus Streptomyces , for which the name Streptomyces gobiensis sp. nov. is proposed.

Streptomyces coffeae sp. nov., an endophytic actinomycete isolated from the root of Coffea arabica (L.)

An endophytic actinobacterium, designated strain CA1R205^T, was isolated from the surface-sterilized root of Coffea arabica L. collected from Ratchaburi province, Thailand. The taxonomic position of this strain was evaluated using a polyphasic approach. The strain produced light yellowish brown to dark brownish black substrate mycelium and greyish white aerial mycelium. The spiral spore chains were produced directly on aerial mycelium. CA1R205^T was found to have ll-diaminopimelic acid in the cell peptidoglycan, galactose, glucose, mannose and ribose as whole-cell reducing sugars, MK-10(H₄), MK-9(H₆), MK-10(H₂), MK-9(H₄), MK-10(H₆) and MK-10(H₈) as menaquinones and iso-C_15 : 0, anteiso-C_15 : 0, iso-C_16 : 0 and C_16 : 0 as major fatty acids. Diphosphatidylglycerol, phosphatidylethanolamine, hydroxyphosphatidylethanolamine, phosphatidylglycerol and phosphatidylinositol were detected in the cells. These characteristics were consistent the typical chemotaxonomic properties of members the genus Streptomyces. The taxonomic affiliation at the genus level of this strain could be confirmed using its 16S rRNA gene sequence data. CA1R205^T showed the highest 16S rRNA gene sequence similarity value to Streptomyces rapamycinicus NRRL B-5491^T (98.9 %), followed by Streptomyces iranensis HM 35^T (98.8 %). Digital DNA-DNA hybridization and average nucleotide identity-by blast (ANIb) values between CA1R205^T and S. rapamycinicus NRRL B-5491^T were 27.2 and 81.5 %, respectively. The DNA G+C content of genomic DNA was 70.7 mol%. Due to the differences in physiological, biochemical and genotypic data, CA1R205^T could be discriminated from its closest neighbour. Thus, CA1R205^T should be recognized as representing a novel species of the genus Streptomyces, for which the name Streptomyces coffeae sp. nov. is proposed. The type strain is CA1R205^T (=TBRC 11244^T=NBRC 114295^T).