Geobacillus toebii sp. nov., a novel thermophilic bacterium isolated from hay compost

Abstract

A thermophilic, spore-forming rod isolated from hay compost in Korea was subjected to a taxonomic study. The micro-organism, designated strain SK-1T, was identified as being aerobic, Gram-positive, motile and rod-shaped. Growth of the isolate was observed at 45-70 °C (optimum 60 °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 mesodiaminopimelic acid in the cell wall and iso-C15:0 and iso-C17:0 as the major cellular fatty acids. The predominant isoprenoid quinone was MK-7. The chemotaxonomic characteristics of strain SK-1T were the same as those of the genus Geobacillus. Phylogenetic analysis based on 16S rDNA sequences showed that strain SK-1T is most closely related to Geobacillus thermoglucosidasius. However, the phenotypic properties of strain SK-1T were clearly different from those of G. thermoglucosidasius. The level of DNA-DNA relatedness between strain SK-1T and the type strain of G. thermoglucosidasius was 27%. On the basis of the phenotypic traits and molecular systematic data, strain SK-1T represents a novel species within the genus Geobacillus, for which the name Geobacillus toebii sp. nov. is proposed. The type strain is strain SK-1T ( = KCTC 0306BPT = DSM 14590T).