水稻土中以硫为电子中介体的硫酸盐还原菌胞外呼吸机制研究

Environmental microbes drive biogeochemical cycle of the most important elements through extracellular respiration gradually attracted more and more attention. However most of the mechanisms were developed by using proteobacteria, e.g. Geobacter sulfurreducens and Shewanella oneidensis. This study focus on sulfate-reducing bacteria extracellular respiration mechanism with sulfur as electronic mediator in typical paddy fields. Field experiment, pot experiment and enrichment of anaerobic bacteria are designed as test systems, integrated application of high-throughput sequencing of large-scale, high flux protein group of quantitative technology on the basis of the transcriptome, macro proteomics method as well. The study mainly discusses the characteristics of soil solution under sulfur stress variation, solid-phase iron reduction kinetics mechanism and morphological transformation which as electron acceptor. Illuminating sulfate-reducing bacteria community structure and quantity change features under sulfur stress, then give a preliminary understanding of sulfur metabolism markers: sulfite reductase and dissimilatory adenosine-5′-phosphosulfate reductase of sulfate-reducing bacteria response to extracellular respiration at the macro transcriptome and proteome level. This research will also set up sulfate-reducing bacteria extracellular respiratory model of paddy soils through the enrichment of sulfate-reducing bacteria culture, and verify the extracellular respiratory function of sulfate-reducing bacteria enrichment. Through the above research, this study will reveal the novel microbial ecological coupling mechanisms of sulfate-reducing bacteria mediated sulfur and mental (iron) biogeochemical cycles through extracellular respiratory in paddy soils.

环境微生物通过胞外呼吸作用推动元素的生物地球化学循环逐渐受到广泛关注。然而，既往的胞外呼吸作用机制研究多集中于变形菌门的地杆菌和希瓦氏菌。本项目以典型稻田土壤中以硫为电子中介体的硫酸盐还原菌胞外呼吸机制为主要研究内容。采用野外原位实验、盆栽实验、厌氧富集菌群等试验体系；综合应用以高通量测序、高通量大规模蛋白组定量技术为基础的宏转录组学、宏蛋白质组学手段；重点探讨硫胁迫下土壤溶液化学变化特征与作为电子受体的固相铁的还原释放动力学机制及其形态转化；研究在此过程中硫酸盐还原菌菌群的结构组成和数量变化特征；在宏转录组和宏蛋白质组水平上初步认识硫代谢的标识物-异化亚硫酸盐还原酶和异化腺苷酰硫酸还原酶对不同硫处理引起硫酸盐还原菌胞外呼吸作用的响应。并通过富集培养研究构建水稻土硫酸盐还原菌胞外呼吸模型以及功能验证。揭示水稻土中胞外呼吸硫酸盐还原菌参与的硫-金属（铁）耦合转化的微生物生态学新机制。

本项目以典型稻田土壤中以硫为电子中介体的硫酸盐还原菌胞外呼吸机制为主要研究内容。采用纯培养菌株、厌氧富集菌群、野外原位实验等试验体系；综合应用以高通量测序、高通量大规模蛋白组定量技术为基础的宏转录组学、宏蛋白质组学手段；重点探讨硫胁迫下作为电子受体的固相铁的还原释放动力学机制及其形态转化；研究在此过程中硫酸盐/硫还原菌菌群的结构组成和数量变化特征；在宏转录组和宏蛋白质组水平上探讨了微生物硫代谢的标识物-异化亚硫酸盐还原酶、异化腺苷酰硫酸还原酶、硫代硫酸盐还原酶对不同硫处理引起硫酸盐还原菌胞外呼吸作用的响应。并通过富集培养研究构建水稻土硫酸盐/硫还原菌胞外呼吸模型以及功能验证。揭示水稻土中胞外呼吸硫酸盐还原菌参与的硫-铁耦合转化的微生物生态学新机制。进一步的拓展性研究发现稻田微生物厌氧氨氧化过程不仅可以间接与硫、铁的氧化还原相耦合；而且可以直接与硫还原过程相耦合。研究提升了稻田厌氧微生物介导元素耦合转化的认知水平。