Isolation, identification and adsorption capacity of a strain resistant to lead, zinc and chromium

Abstract:

[Background] The problem of heavy metal pollution caused by mining has caused great harm to the ecological environment and human health. Therefore, the problem of heavy metal pollution in mining areas needs to be solved urgently. Biological remediation method has low cost, wide resources and no secondary pollution. It is an effective way to remediate soil heavy metal pollution. [Objective] Using the soil around a coal gangue mountain in Qufu city, Shandong province as a material, a strain with high tolerance to lead, zinc, and chromium and strong adsorption capacity was separated and selected by the flat line method. [Methods] Morphological characteristics, physiological and biochemical identification, and molecular biology methods were used to identify the strain. The concentration of each heavy metal was measured by an atomic absorption photometer. [Results] The identified strain was Bacillus cereus, named Bacillus cereus MZ-11. The strain MZ-11 can grow normally when the pH was 5.5?8.5, the temperature was 15?45 °C, and the NaCl mass fraction was 2%?8%. The strain MZ-11 had the highest resistance to lead, zinc and chromium up to 1 000, 1 200 and 1 600 mg/L. The three heavy metal concentrations of lead, zinc, and chromium in the medium were the initial concentration (containing Pb2+, Zn2+, and Cr6+ at 50, 60, and 80 mg/L, respectively), and the initial concentration was 5 times, 10 times, and 20 times. As the concentration increased, the adsorption ratio of strain MZ-11 to Cr6+ and Zn2+ gradually increased, and the adsorption percentages were all above 98%?99%. Under the condition that the Pb2+ concentration was 5 times the initial concentration, the adsorption ratio of MZ-11 to Pb2+ reached the maximum 97.01%. [Conclusion] Strain MZ-11 has high tolerance to lead, zinc and chromium and good adsorption capacity, which provides strong theoretical support for bioremediation of heavy metal pollution in the mining area and ecological environment of the mining area.

Key words:Lead zinc chromium resistant strains, Strain identification, Bacillus cereus, Adsorption capacity