Isolation and Molecular Identification of New Thermophilic Bacterial Strains of Geobacillus pallidus and Anoxybacillus flavithermus.

A total of 30 bacterial strains were isolated from water samples obtained from four different hot springs in Jordan; 6 from Hammamt Al-Burbita, 7 from Afra hot springs, 11 from Ma'in hot springs, and 6 from North Shuna hot springs. One representative strain was selected from each site for further analysis. The selected strains were S1-1 from Hammamt Al-Burbita, S2-1 from Afra hot springs, S3-1 from Ma'in hot springs, and S9-6 from North Shuna hot springs. Based on 16S rDNA sequence analysis, three strains (S1-1, S2-1, and S3-1) were identified as new strains of Geobacillus pallidus. Sequencing and BLAST search of 16S rDNA sequences of the three strains revealed 98% identity for S1-1, and 97% identity for strains S2-1 and S3-1 with G. pallidus. The fourth strain, S9-6, which was isolated from North Shuna hot springs, showed lower identity percentage (94%) with its closest relative Anoxybacillus flavithermus. This initially suggests that S9-6 represents a new species of Anoxybacillus. Despite the different phylogenetic affiliation of the strains, they all exhibited an optimum growth temperature (Topt) of 60?C. This defines them as moderately thermophilic bacteria. Strains belonging to the thermophilic bacterial genera Geobacillus and Anoxybacillus are recorded for the first time for the above mentioned hot springs.