Abstract
A thermophilic, spore-forming rod isolated from hay compost in Korea was subjected to a taxonomic study. The micro-organism, designated strain SK-1(T), was identified as being aerobic, Gram-positive, motile and rod-shaped. Growth of the isolate was observed at 45--70 degrees C (optimum 60 degrees C) and pH 6.0--9.0 (optimum pH 7.5). The G+C content of the genomic DNA was 43.9 mol%. Chemotaxonomic characteristics of the isolate included the presence of meso-diaminopimelic acid in the cell wall and iso-C(15:0) and iso-C(17:0) as the major cellular fatty acids. The predominant isoprenoid quinone was MK-7. The chemotaxonomic characteristics of strain SK-1(T) were the same as those of the genus Geobacillus. Phylogenetic analysis based on 16S rDNA sequences showed that strain SK-1(T) is most closely related to Geobacillus thermoglucosidasius. However, the phenotypic properties of strain SK-1(T) were clearly different from those of G. thermoglucosidasius. The level of DNA--DNA relatedness between strain SK-1(T) and the type strain of G. thermoglucosidasius was 27%. On the basis of the phenotypic traits and molecular systematic data, strain SK-1(T) represents a novel species within the genus Geobacillus, for which the name Geobacillus toebii sp. nov. is proposed. The type strain is strain SK-1(T) (=KCTC 0306BP(T)=DSM 14590(T)).