Streptomyces acidipaludis sp. nov., an actinobacterium isolated from peat swamp forest soil

An actinobacterium strain PLK6-54^T was isolated from Lankwai peat swamp forest soil collected from Yala province, Thailand. Strain PLK6-54^T exhibited morphological and chemotaxonomic properties described for the genus Streptomyces. It formed a spiral spore chain directly on aerial mycelium. Growth was observed between 20 and 40 °C and at pH 5-8. The maximum NaCl for growth was 2 % (w/v). ll-Diaminopimelic acid, arabinose and ribose were detected in the whole-cell hydrolysate. Diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol and phosphatidylinositolmannoside were detected as the phospholipids. The major menaquinones were MK-10(H₂) and MK-9(H₆). The major cellular fatty acids were iso-C_16 : 0, anteiso-C_15 : 0 and iso-C_14 : 0. 16S rRNA gene sequence data supported the assignment of strain PLK6-54^T to the genus Streptomyces and showed that Streptomyces rubidus NBRC 102073^T (99.0 %) was the closest relative. Moreover, the average nucleotide identity-blast (85.5 %) and digital DNA-DNA hybridization (30.7 %) values reported between strain PLK6-54^T and its closest neighbour were below the threshold values for delineation of a novel species. Strain PLK6-54^T could be distinguished from related validly described Streptomyces species by several phenotypic properties. The combination of genotypic and phenotypic data indicated that strain PLK6-54^T is representative of a novel species of the genus Streptomyces. The name Streptomyces acidipaludis sp. nov. is proposed for strain PLK6-54^T. The type strain is PLK6-54^T (=TBRC 11250^T=NBRC 114297^T).

Streptomyces genisteinicus sp. nov., a novel genistein-producing actinomycete isolated from a Chinese medicinal plant and proposal of Streptomyces michiganensis Corbaz et al. 1957 as a later heterotypic synonym of Streptomyces xanthochromogenes Arishima et al. 1956

A novel genistein-producing actinobacterial strain, designated strain CRPJ-33^T, was isolated from the healthy leaves of a medicinal plant Xanthium sibiricum collected from Hunan Province, PR China. 16S rRNA gene sequence analysis indicated strain CRPJ-33^T belonged to the genus Streptomyces and had 99.7, 99.0, 98.9, 98.9, 98.8 and 98.7% sequence similarities to Streptomyces zhihengii YIM T102^T, Streptomyces eurocidicus NRRL B-1676^T, Streptomyces xanthochromogenes NRRL B-5410^T, Streptomyces michiganensis NBRC 12797^T, Streptomyces mauvecolor LMG 20100^T and Streptomyces lavendofoliae NBRC 12882^T, respectively. Phylogenetic analysis of 16S rRNA gene sequences showed that strain CRPJ-33^T was most closely related to S. zhihengii YIM T102^T. However, digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) values between them were much less than the recommended threshold values. Furthermore, differential comparisons of the phenotypic characteristics were enough to distinguish strain CRPJ-33^T from S. zhihengii YIM T102^T. Meanwhile, the ANI and dDDH values or MLSA distances between strain CRPJ-33^T and other type strains, which exhibited ≥98.7 % 16S rRNA gene sequence similarities to strain CRPJ-33^T, were far away from the recommended threshold values. Based on these results, it is thought that strain CRPJ-33^T should represent a novel species of the genus Streptomyces, for which the name Streptomyces genisteinicus sp. nov. is proposed. The type strain is CRPJ-33^T (=MCCC 1K04965^T=JCM 34526^T). In addition, the phenotypic, chemotaxonomic and genotypic characteristics, as well as phylogenetic information revealed that the type strains of S. xanthochromogenes and S. michiganensis should belong to same genomic species. Consequently, it is proposed that S. michiganensis is a heterotypic synonym of S. xanthochromogenes for which an emended description is given.