Streptomyces gramineus sp nov., an antibiotic-producing actinobacterium isolated from bamboo (Sasa borealis) rhizosphere soil

Two actinobacterial strains, JR-43(T) and JR-4, were isolated from bamboo (Sasa borealis) rhizosphere soil. The isolates produced grey aerial mycelium and a yellow soluble pigment on ISP 4. Microscopic observation revealed that strains JR-43(T) and JR-4 produced rectiflexibiles spore chains with spiny surfaces. Both isolates had antibacterial activity against plant-pathogenic bacteria, such as Xanthomonas campestris LMG 568(T) and Xanthomonas axonopodis pv. vesicatoria LMG 905. The isolates contained iso-C-14:0, iso-C-15:0, anteiso-C-15:0 and iso-C-16:0 as the major fatty acids and MK-9(H-6) and MK-9(H-8) as the major isoprenoid quinones. Phylogenetic analysis of the 16S rRNA gene sequences of strains JR-43(T) and JR-4 showed that they grouped within Streptomyces cluster II and had highest sequence similarity to Streptomyces seoulensis NBRC 16668(T) and Streptomyces recifensis NBRC 12813(T) (both 98.2% 16S rRNA gene sequence similarity). DNA DNA relatedness between strain JR-43(T) and S. seoulensis NBRC 16668(T) and S. recifensis NBRC 12813(T) ranged from 31.42 to 42.92%. Based on DNA DNA relatedness and morphological and phenotypic data, strains JR-43(T) and JR-4 could be distinguished from the type strains of phylogenetically related species. They are therefore considered to represent a novel species of the genus Streptomyces, for which the name Streptomyces gramineus sp. nov. is proposed. The type strain is JR-43(T) (=KACC 15079(T) =NBRC 107863(T)). Strain JR-43 (=KACC 15078 =NBRC 107864) is a reference strain.