Streptomyces telluris sp. nov., a promising terrestrial actinobacterium with antioxidative potentials.

An actinomycete strain, AA8, which produced a long straight chain of spores (verticillati type), was isolated from the rhizosphere soil of Mangifera indica in Bangkok, Thailand. A polyphasic taxonomic study was carried out to establish the taxonomic position of the strain. Strain AA8 formed a tight taxonomic position in the 16S rRNA gene tree with Streptomyces roseifaciens MBT76. In contrast, the genome-based taxonomic analysis showed that strain AA8 shared low average nucleotide identity-BLAST (94.1%), the digital DNA-DNA hybridization (58.2%), and the average amino acid identity (93.6%) values with S. roseifaciens MBT76. Moreover, a combination of physiological and biochemical properties indicated that strain AA8 was distinguished from all Streptomyces species with effectively published names. Strain AA8, therefore, represents a novel species of Streptomyces, and the name Streptomyces telluris is proposed for the strain. The type strain is AA8 (= TBRC 8483 = NBRC 113461). The chemical investigation led to the isolation of nine known compounds (compounds 1-9). Among these compounds, compound 7 (3,4-dihydroxybenzaldehyde) possesses strong antioxidant activity equal to ascorbic acid, a powerful antioxidative agent.