Abstract:Bacterium mixed with acidophilic thiobacillus ferrous oxide, ferrous oxide hook spirochete and sulfur oxide thiobacillus was applied as materials to investigate effect of chlorine ion concentration stress on activity of mixed bacterium through analyzing pH value, Eh value, concentration of Fe2 and total iron in medium. Stress effect of Cl- concentration in uranium-leaching solution on growth activity of mixed bacterium is characterized by bacterial specific growth rate under different Cl- concentrations fitted by ratio of [Fe2 ]/[Fe3 ] and bacterial obtainment coefficient rate on Fe2 . The results show that mixed bacterium is tolerant to Cl-. Cl- with concentration of ≤1.0 g/L in cultured medium has no effect on growth and activity of mixed bacterium. Growth and activity of thiobacillus ferrooxidans are obviously influenced by Cl- with concentration of 1.0~5.0 g/L. Growth and activity of mixed bacterium are completely inhibited when Cl- concentration is 10.0 g/L.