Optimizing the Reduction of Molybdate by Two Novel Thermophilic Bacilli Isolated from Sinai, Egypt.

The aim of this study was to isolate thermophilic bacteria to be used in in situ bioremediation of molybdate at elevated temperatures. Two molybdate reducing bacteria (Pharon2 and Pharon3) were isolated from the hot Spring at Pharaoh's Bath, Sinai, Egypt. The isolates were identified by 16S rRNA genes sequencing and were submitted to GenBank as Bacillus tequilensis strain Pharon2 (MK078034) and Bacillus sonorensis strain Pharon3 (MK078035). The molybdenum blue production was optimized using multifactorial statistical approaches, Plackett-Burman and central composite designs. According to the results obtained by response optimizer, the maximum molybdenum blue production achieved was 1.04 and 1.12 represented as absorbance at 865 nm, with the optimum salt concentration of 1.1 and 2.5%; at pH 7.02 and 7.07; incubation temperature of 46.1 and 52.2 °C; sucrose and glucose as an electron donor for Bacillus tequilensis strain Pharon2 and Bacillus sonorensis strain Pharon3, respectively. In conclusion, the thermophilic bacterial isolates belonging to the genus Bacillus could be used in in situ bioremediation under elevated temperatures. To the best of our knowledge, this is the first record of molybdenum blue production by thermophilic Bacillus tequilensis and Bacillus sonorensis.