Works on U(VI) resistance, biochemistry and environmental biotechnology bacillus vallismortis and bacillus mojavensis

Bioaccumulation and resistance of Uranium(VI) were experimented by using thermotolerant Bacillus vallismortis and Bacillus mojavensis. The minimum inhibition concentration of (MIC) values of U(VI) was found to be 82,5 mg/L for B. vallismortis and 85 mg/L for B. mojavensis. The effect of various U(IV) concentrations on the growth and bioaccumulation on B. vallismortis and B. mojavensis were investigated in the liquid culture media. It was found that the bacteria in liquid media was more sensitive than in the solid media. What was obtained from this study is that there was diversity in the various periods of the growth phases of uranium bioaccumulation capacities, which were shown by B. vallismortis and B. mojavensis. The highest U(VI) bioaccumulation capacities of B. vallismortis and B. mojavensis were determined to be 50 and 48,2 mg/g dried bacteria, respectively. The effect of various concentration of U(VI) on α-amylase production by using B. vallismortis and B. mojavensis was also tested. In addition to these, uranium(VI) ions were preconcentrated with immobilized B. vallismortis and B. mojavensis onto multiwalled carbon nanotube (MWCNT) and XAD-4 resin and were determined by UV-vis spectrophotometry. The effect of several factors such as pH, flow rate of solution, amount of biosorbents and support materials, eluent type, concentration and volume, the foreing ions, sample volume and reusage of solid phase extraction columns on retention of U(VI) were studied and extraction conditions were optimized. The characterization of immobilized B. vallismortis and B. mojavensis onto MWCNT and XAD-4 resin with and without U(VI) were examined by FT-IR and SEM. The certified reference materials were utilized for the validation of new solid phase extraction methods. The new validated methods were applied for the determination of U(VI) in natural samples. Keywords: Bacillus vallismortis, Bacillus mojavensis, uranium(VI), resistance, bioaccumulation, solid phase extraction, UV-vis spectrophotometer