Polyphasic identification of a thermophilic bacterium from geyser of Cisolok, Indonesia

A thermophilic bacterium strain UICC B-76 was isolated from litter in geyser of Cisolok, West Java, Indonesia by using The International Streptomyces Project (ISP1) medium. The strain UICC B-76 was able to hydrolyze various substrates such as casein, cellulose, gelatin, starch, and xylan, at 50 °C, and decolorize Remazol Brilliant Blue R (RBBR) at 50 °C, an indicator for ligninolytic degradation ability. These abilities of strain UICC B-76 suggest its potential for industrial applications. The aim of this study was to identify strain UICC B-76 based on phenotypic and genotypic characterizations. Strain UICC B-76 was Gram-positive, spore-forming, aerobic and facultative anaerobic, and rod-shaped with flagella. The strain grew at 30 °C to 60 °C (optimum 50 °C) and pH 7.0 but can not withstand temperature of 70 °C as well as pH 4.0 and 9.0. Strain UICC B-76 could not grow in more than 1% NaCl. This strain has menaquinone 7 (MK-7) as the major quinone system; cell wall fatty acids consisted of Iso-C15:0 (68.56%), Iso-C17:0 (12.48%), and Anteiso-C15:0 (8.45%); and the main amino acids of the cell wall was meso-diaminopimelic acid (meso-DAP). Phylogenetic analysis based on the full sequence of 16S rRNA gene (1450 nt) indicated that strain UICC B-76 belongs to the genus Brevibacillus (Family Paenibacillaceae, Order Bacillales, Class Bacilli, Phylum Firmicutes). Strain UICC B-76 was closely related with type strains of Brevibacillus parabrevis and those of B. agri, however, strain UICC B-76 was separated from both species. The 16S rDNA sequence similarity of strain UICC B-76 showed relatively low sequence homology value, less than 99%, to the type of strains B. parabrevis (ranged between 98.13% and 98.20%) and B. agri (98.13%). Moreover, the G+C content of strain UICC B-76 (55 mol%) differs with B. parabrevis (51.8-52.2 mol%) and B. agri (53.5 mol%). This result indicated that strain UICC B-76 may represent a new species of Brevibacillus. Hybridization of DNA among strain UICC B-76, B. parabrevis and B. agri is required to clarify the proposal of a new species.