微生物介导土壤Pb(II)转化成磷铅矿的生物-化学耦合机制

The contamination of soil environments with toxic heavy metal Pb is a problem of global concern. One of the most effective Pb(II) remediation strategies is to promoting the transformation of soil Pb into pyromorphite. Previous studies have confirmed the feasibility of biomineralization from Pb(II) into pyromorphite mediated by microbes, leading to the immobilization of soil Pb. However, little attention has been paid to in-depth understanding of pyromorphite formation process and its regulation mechanism under microbe activity. In this project, a Pb(II) resistant Bacillus cereus ZQY12-2 strain isolated from lead–zinc mine tailings will be used to investigate the biomineralization of Pb(II) into pyromorphite. A stepwise biomineralization hypothesis of “Pb enrichment - sedimentary - crystallization” is proposed, connecting the process of Pb(II) adsorption /complexation with metallogenesis. Combining micro/mesoscopic analysis, molecular biological techniques and mineralogical methods, systematic survey the micro-mechanism of Pb(II) transformation from ionic type to pyromorphite minerals and its regulation will be carried out. Chemical and biological mechanisms of soil Pb(II) immobilization and biomineralization mediated by microbes will be revealed. Results from this project are expected to provide scientific basis for soil Pb(II) immobilization and technical support for the development of in situ bioremediation technologies for Pb(II)-contaminated soil.

土壤中Pb污染引发的环境安全问题备受关注。促进土壤Pb转化形成磷铅矿是有效的Pb污染原位修复策略之一。已有研究证实微生物能够介导土壤Pb转化为磷铅矿，从而实现土壤Pb的钝化，然而对Pb的成矿过程和调控机制并没有深入的认识。为此，本项目以一株铅锌矿尾矿分离的铅成矿菌Bacillus cereus ZQY12-2为例，将微生物对Pb(II)吸附/络合与成矿过程联系起来，提出微生物介导“Pb富集-沉积-晶化”三步成矿假说。综合利用微/介观分析方法、分子生态学和矿物学手段，系统研究ZQY12-2菌株介导下Pb(II)转化形成磷铅矿的过程、矿物演变规律和调控机制，探讨ZQY12-2菌株对土壤Pb(II)迁移转化的影响，揭示土壤Pb(II)转化形成磷铅矿的生物-化学机制，拓宽对土壤Pb(II)生物成矿机理的认识，为Pb(II)污染土壤的修复提供理论依据与技术支撑。

促进环境中的Pb 转化形成磷铅矿物被认为是Pb污染修复最有效的方法之一。本项目以Pb(II)锌矿尾矿、污泥堆肥等Pb(II)污染场地分离的Pb(II)成矿菌（B. cereus ZQY12-2、B. thuringiensis 016、T. thermophilus FAFU013）为研究对象，系统研究微生物介导的羟基磷酸钙铅（Ca2.5Pb7.5(OH)2(PO4)6）、磷氯铅矿（Pb5(PO4)3Cl）等矿物的形成与演变过程及其成矿规律和调控机制，明确成矿细菌在磷Pb(II)矿成矿过程的角色与功能，提出“Pb富集−沉积−晶化”3步成矿假说，揭示Pb(II)微生物成矿过程的化学-生物机制。此外，本项目还针对污泥高温堆肥中重金属铅超标的问题，开发超高温堆肥重金属原位钝化技术，通过超嗜热铅成矿菌，快速促进迁移态的铅转化成稳定、难溶的磷氯铅矿晶体矿物，实现铅的有效钝化。本研究不仅拓宽了对微生物介导土壤Pb(II)形态转化机理的认识，也为Pb(II)污染环境的原位修复提供理论依据与技术支撑。