狼尾草根际土壤的阿特拉津降解功能微生物鉴定

Microbial degradation is an important way of self-purification of soil atrazine .Excavating the potential efficient atrazine degrading microorganisms, clearing their degradation mechanisms has great significance on soil atrazine bioremediation. Using stable isotope probing techniques and 454 high-throughput sequencing technology as a means, our project will make unknown metabolic functions of microorganisms and atrazine degradation process linked. On the basis of identifying atrazine microbial degradation processes and mechanisms, we will research the species composition and evolution of soil atrazine degrading microorganisms in rhizosphere and non-rhizosphere soil, especially uncultured functional microbial, excavate atrazine degradation microorganisms resources. Combination of atrazine metabolites, we will reveal the processes and mechanisms of degradation. Using Biolog and DGGE technologies to reveal the succession characteristics of metabolic diversity and community structure diversity of soil microorganisms in rhizosphere and non-rhizosphere, Utilizing qPCR method to research the population evolution and the number of typical uncultured atrazine degradation microorganisms in atrazine degradation process. revealing the important role of soil-microbes-plant "Commonwealth" in atrazine contaminated soil self-purification process. Making a theoretical basis and technical support for the development of soil organic pollution remediation.

微生物降解是土壤阿特拉津自净的重要途径。发掘潜在高效的阿特拉津降解微生物、明确其在降解过程中的作用和机制对土壤阿特拉津污染生物修复具有重要意义。本项目以稳定性同位素探针和454高通量测序技术为手段，将未知土壤微生物种群代谢功能和阿特拉津降解过程直接联系。在辨明土壤阿特拉津微生物降解过程的基础上，着重研究狼尾草根际土壤中阿特拉津降解微生物种群组成和演变，尤其是不可培养功能微生物，挖掘阿特拉津降解功能微生物资源。结合降解产物分析，揭示其降解过程和机制。运用Biolog和DGGE等技术揭示狼尾草根际、非根际土壤微生物代谢多样性和群落结构多样性在阿特拉津降解过程中的演替特征。运用实时荧光定量RT-qPCR技术，研究典型不可培养阿特拉津降解微生物在降解过程中的演变情况。为揭示土壤-微生物-植物"联合体"在阿特拉津污染土壤自净过程中的重要作用，丰富和发展土壤有机污染修复技术提供理论依据和技术支撑。

采用盆栽根袋培养法，研究了狼尾草对阿特拉津污染土壤的根际降解作用。结果表明，盆栽培养28 d后，狼尾草对阿特拉津污染土壤有较好的根际强化降解效果，狼尾草根际土壤阿特拉津去除率为52.70 %，非根际土壤的阿特拉津去除率为37.60%。土壤自身具有修复阿特拉津的潜能，湛江砖红壤中阿特拉津降解以非生物降解为主，降解率为16.90%，土著微生物对阿特拉津的生物降解效果弱于非生物降解，为11.70%。狼尾草通过根际效应显著提高了土壤总微生物数量和活性，增加了土壤可培养细菌、真菌和放线菌的数量，尤其是土壤可培养细菌数量，提升了土壤细菌群落结构的丰富度和均匀度，进而间接强化土壤阿特拉津的生物降解。狼尾草根际作用显著提升了土壤中生物可利用态阿特拉津的含量，降低了土壤结合态和腐殖质固定态阿特拉津含量。狼尾草体内累积态阿特拉津主要富集在狼尾草的根系部位，含量非常微少。狼尾草根际作用可显著降低根际周围土壤的pH值、富里酸、胡敏酸和胡敏素的含量。土壤pH越高、富里酸、胡敏酸和胡敏素含量越低，对应的生物可利用态阿特拉津含量就越高，土壤结合态和腐殖质固定态阿特拉津含量越低。与根际土壤pH值降低导致的影响相比，狼尾草消耗有机质起到的解吸附作用在决定狼尾草根际土壤中阿特拉津的形态分布占主导地位。通过DNA-SIP和高通量测序技术相结合，原位鉴定狼尾草根际的阿特拉津降解微生物为Kaistobacter, Rhodanobacter, Rhodoplanes, Ramlibacter, Pseudonocardia和Planctomyces。