Screening and identification of Cr(VI) reducing bacteria

Abstract:

[Background] Chromium-contaminated soil is a key target for soil pollution remediation in China. In many remediation technologies, microbial method has become a research hotspot because of its simple, economical, and no secondary pollution. It is particularly important to screen strains that can adapt to the polluted site environment and efficiently reduce Cr(VI) in the microbial method. [Objective] Screening strains adapted to the efficient reduction of Cr(VI) in cold and arid regions of Northwest China, enrich the resource pool of chromium reducing bacteria, and lay the foundation for remediation of chromium-contaminated soil. [Methods] Screening bacteria by enrichment, domestication, isolation and purification; the target strain was identified by a combination of morphology and molecular biology; and the reduction mechanism was studied by fourier transform infrared spectroscopy. [Results] G-13 has strong Cr(VI) reducing ability. At pH 9.0 and temperature 30 °C, the reduction rate reached 82.8% in a 100 mg/L Cr(VI) solution within 60 hours. Morphological and molecular biological identification showed that the strain G-13 was Micrococcus luteus. The decrease of Cr(VI) in the reaction was accompanied by the increase of Cr(III), which indicated that the reduction reaction was the main factor, and the reducing ability was dependent on the growth of bacteria. Studies on cell components and denaturation showed that extracellular enzymes play a major role in the reduction reaction. Except for Pd2+ and Cd2+, the other metal ions had no significant inhibitory effect on enzyme activity. Through fourier transform infrared spectroscopy analysis, it was found that the binding sites of G-13 and Cr(VI) were mainly –OH, C=O, ?COOH, ?CH, –CONH2 and so on. [Conclusion] G-13 has strong Cr(VI) reducing ability, and can be used to rich bacterial resources for repairing chromium-contaminated soil in northwestern cold and arid regions.