Abstract

This research came to screen the bioremediation of lead in water by thermophilic Iraqi isolate of Bacillus stearothermophilus at different temperature. Lauria bertani broth with or without pb was used as control for assessing bioremediation. The bacterium B. stearothermophilus was grown for five hours as a starter culture, then LB or LB+ pb were inoculated by starter culture incubated for 24-72 h at 55°C and the remaining of pb was detected to screen bioremediation ability of studied bacterium. Another experiment was conducted to screen pb reduction in water at 55°C. The Iraqi isolate of B. stearothermophilus could eliminate more than half of pb after 48 h, time elongation had no effect on bioremediation. In water the elimination of pb was dependent on bacterial activity, temperature and time, in which cell biomass caused a decrease in pb concentration from 0.775 to 0.122 at 55°C compared with cell debris the eliminate 0.354 ppm of pb. Less reduction of pb concentration in water was recognized at 25°C for both cell biomass and cell debris.