Streptomyces siamensis sp. nov., and Streptomyces similanensis sp. nov., isolated from Thai soils

Three actinomycete strains, KC-038T, KC-031 and KC-106T, were isolated from soil samples collected in the southern Thailand. The morphological and chemotaxonomic properties of strains KC-038T, KC-031 and KC-106T were consistent with the characteristics of members of the genus Streptomyces, that is, the formation of aerial mycelia bearing spiral spore chains; the presence of LL-diaminopimelic acid in the cell wall, MK-9 (H6), MK-9 (H4) and MK-9 (H8) as the predominant menaquinones; and C16:0, iso-C16:0 and anteiso-C15:0 as the major cellular fatty acids. 16S rRNA gene sequence analyses indicated that strains KC-038T and KC-031 were highly similar (99.9%), and they were closely related to S. olivochromogenes NBRC 3178T (98.1%) and S. psammoticus NBRC 13971T (98.1%). Strain KC-106T was closely related to S. seoulensis NBRC 16668T (98.9%), S. recifensis NBRC 12813T (98.9%), S. chartreusis NBRC 12753T (98.7%) and S. griseoluteus NBRC 13375T (98.4%). The values of DNA–DNA relatedness between the isolates and the type strains of the related species were below 70%. On the basis of the polyphasic evidence, the isolates should be classified as two novel species, namely Streptomyces siamensis sp. nov. (type strain, KC-038T=NBRC 108799T=PCU 328T=TISTR 2107T) and Streptomyces similanensis sp. nov. (type strain, KC-106T=NBRC 108798T=PCU 329T=TISTR 2104T).