苏云金芽孢杆菌富集铬离子的性能与机理研究

Bacillus thuringiensis (Bt), a kind of gram-positive bacterium widely occurring in different types of soils, can produce parasporal crystals during its metabolization. The parasporal crystals of Bt consist of many kinds of proteins with high molecular mass, therefore it is possible to bioaccumulate the heavy metals by complex. However, little is known about the bioaccumulation of heavy metal ions with Bt, especially their interaction mechanisms. Therefore, with common founded Cr ions as target, the project focuses on the adaptability, tolerability, accumulation, and reduction, and then evaluates the ability of biological detoxification of growing Bt with different Cr species including Cr(III) and Cr(VI). This research will also discuss the possible mechanisms of biological detoxification for Cr ions by analysis on sub-cellular structure, genome change, and plasmid damage, as well as the effect of metabolization on its bioaccumulation. On that basis, our research will investigate the potential of Bt in the treatment of leather industry wastewater containing different concentration levels of Cr ions. The results will help understand the mechanisms of transport and transformation, as well as support the risk assessment of heavy metal ions.

苏云金芽孢杆菌（Bt）广泛分布于各种土壤介质中，是一类代谢过程中可产生伴孢晶体的革兰氏阳性细菌。由于Bt的伴孢晶体由多种高分子蛋白组成而具有富集重金属的潜在优势，但目前缺少Bt富集重金属的相关研究，尤其是机理研究。为此，本项目以Bt为研究对象，以重金属Cr为目标物，拟通过开展Bt对Cr(III)和Cr(VI)的适应性、耐受性、富集量以及Bt对Cr(VI)的还原作用研究，掌握Bt富集重金属的生物脱毒性能；通过对富集Cr(III)和Cr(VI)的Bt进行亚细胞结构观察，基因组水平、质粒变化分析及代谢与生物富集的关系研究，探讨Bt富集重金属的生物脱毒机理。在此基础上，选择制革工业废水进行Bt处理含铬废水的方法研究，考察Bt在处理重金属污染工业废水方面的潜力。本项目将对认识重金属的迁移转化规律及其风险评估具有重要意义。

苏云金芽孢杆菌（Bt）的伴孢晶体由多种高分子蛋白组成而具有富集重金属的潜在优势，但目前缺少Bt 富集重金属的相关研究。为此，本项目利用微生物受自然环境重金属胁迫而产生耐性这一特点，进行土壤中耐 Cr 微生物的筛选研究，成功获得两株耐 Cr的菌株。初步探讨了B. dabaoshanensis GSS04菌株的生长特性和铬还原特性，建立了微生物-Cr(VI)还原转化的反应体系。探讨了C. humireducens MFC5的铬还原特性，建立了铁还原菌－腐殖质－土壤矿物－Cr(VI)还原体系，阐述了铁循环与Cr(VI)转化的微界面生物化学过程，并厘清了铁还原菌、电子穿梭体、铁物种的角色与功能，揭示了铁还原菌－腐殖质－土壤矿物－Cr(VI)还原体系中Cr(VI)还原机制。针对微生物铬还原机制，初步建立了重金属修复的铁还原菌-腐殖质-矿物及铁还原菌/生物炭的原位钝化技术，实现了土壤重金属的原位钝化。上述研究既为理解土壤/水体中重金属自然消减过程与机理提供理论依据，又为建立基于微生物的土壤重金属原位生物修复策略提供技术支撑。