典型酸、碱性锑污染土壤中锑氧化过程的微生物学机制

Antimony(III) (Sb(III)) is more toxic than antimony(V) (Sb(V)), hence, the oxidization of Sb(III) detoxes the contamination of Sb. Microorganisms play essential roles in biogeochemical cycling of Sb, including antimonite(Sb(III)) oxidation. Therefore, study on microbial community composition and functions of antimonite oxidizers is responsible for ecological restoration of Sb-contaminated areas. However, oxidation of Sb(III) is mainly explored with pure cultures in laboratory, there is still a lack of comprehensive understanding for the antimonite oxidizers in the environment. In this proposed project, acidic (Xikuangshan) and alkaline (Nandan antimony mining area) antimony-contaminated soils are used to set up microcosms to study profiles of antimonite oxidation driven by microorganisms. Quantitative PCR technique is used to study responses of Sb(III)-oxidizing genes, i.e. aioA and anoA, to antimonite oxidation in the soils. Combination of high through sequencing and DNA-SIP technique is employed to investigate microbial community structures and their responses to the antimonite oxidation, and thereby to reveal the activate antimonite oxidizers in the soils. Furthermore, whole genome shotgun (WGS) method is used to elucidate microbial mechanism of antimonite oxidation in the soils. This study is hopeful to deepen the understanding for mechanism of ecological remediation of contamination caused by Sb, which is meaningful in both scientific researches of Sb cycling and practical application of restoration of Sb-contamination.

三价锑毒性高于五价锑，锑氧化过程(Sb(III)→Sb(V))可降低锑污染毒性。微生物广泛参与锑的地球化学循环，包括锑氧化过程。研究锑氧化微生物的群落组成及其功能特征对锑污染的修复具有重要意义。但目前有关微生物锑氧化的研究主要集中于纯培养实验，对环境样品中锑氧化微生物群落依然缺乏清晰的认识。本项目拟选取典型酸性（锡矿山）和碱性（南丹锑矿区）锑污染土壤为研究对象，通过微宇宙培养技术，深入研究土壤中微生物驱动的锑氧化过程。应用定量PCR技术，研究参与锑氧化的功能基因aioA和anoA对锑氧化过程的响应。利用高通量测序技术，结合同位素标记（DNA-SIP）技术，查明微生物群落对锑氧化过程的响应，揭示土壤中关键的锑氧化微生物。通过基于宏基因组的微生物代谢功能研究，阐明酸性和碱性锑污染土壤中锑氧化过程的微生物机制。该研究有望深化锑污染地区生态修复机理的认识，具有较强的科学研究价值和实际指导意义。

本项目瞄准我国不同类型（酸性和碱性）土壤中突出存在的砷/锑污染问题，探索酸性和碱性土壤中自养型砷/锑氧化的地球化学过程及其微生物学机制。本项目调查了多个矿区周边酸性和碱性土壤的金属污染情况以及土壤中关键元素的地球化学特征，分析了土壤中微生物群落结构情况，以及微生物对砷、锑等金属污染的响应；依托于自养型砷/锑氧化这一研究课题，开发了稳定同位素示踪-宏基因组-单菌组草图组装联用平台，鉴定不同污染土壤中的自养型砷/锑氧化细菌，获得了自养型好氧/厌氧砷/锑氧化过程在不同类型土壤中广泛存在的地球化学证据，并揭示上述过程的微生物学机制，同时，也对土壤中砷/锑循环与营养元素碳、氮循环的耦联作用进行了探讨和研究。本项目的研究成果可能为降低砷/锑污染的毒性和迁移性提供科学依据，为实现砷/锑污染场地的生态修复提供理论指导。