复合功能菌群强化能源植物蓖麻异位修复铅锌污染底泥的效应与机理研究

Using Ricinus communis L. for the remediation of Pb-Zn contaminated sediment is a promising method, which has both environmental and economic benefits. However, it is easily subjected to small biomass and poor resistance of the plant and would lead to the loss of treatment effect and economic value. Thus, how to improve the biomass and resistance of Ricinus communis L., i.e. phytoremediation always is a research hotspot in pollution remediation field. Many studies have been focused on the use of single plant growth promoting bacteria to enhance phytoremediation of Ricinus communis L.. While, there is few reports about selecting multi-strain composite system purposefully to enhance the ability of phytoremediation according to the pollution characteristics. In this case, if we can strengthen the rhizosphere of Ricinus communis L. by constructing the complex functional microbial communities that not only have lead and zinc resistance but also promote plant growth, then its resistance and biomass would enhance significantly, i.e. high environmental adaptability and lead uptake can be given to the plant for phytoremediation. It is of great significance for the remediation of Pb-Zn contaminated sediment. Therefore, this project is intended to systematically study on the energy plant resistant to lead and zinc, Ricinus communis L. enhanced functional microbial communities, for the ex-situ remediation of Pb-Zn contaminated sediment. It is planned to reveal the mechanism of interaction between Ricinus communis L.and the functional microbial communities in the ex-situ remediation of Pb-Zn contaminated sediment process through investigating the effects of the functional microbial communities on the uptake and translocation of lead and zinc in Ricinus communis L., analyzing antioxidant system response and metabonomics in Ricinus communis L., and recording the evolution of the functional microbial communities in different growth stage and the environment change in root zone of Ricinus communis L.in its whole growth cycle.

生物量小、抗逆性差是影响蓖麻修复铅锌污染底泥效果和经济利用价值的主要限制性因素。目前利用单一植物促生菌强化植物修复的研究较多，但根据污染特性，有目的地选取多菌株复合体系用于强化植物修复能力的研究却鲜有报道。通过构建具有耐铅锌与植物促生性能的复合功能菌群用以强化蓖麻根际对环境的适应性与修复能力，显著增强其抗逆性并有效提高其生物量，对铅锌污染底泥的修复具有重要的理论意义和实际应用价值。申请项目拟以耐铅锌能源植物蓖麻为研究对象，将所构建的复合功能菌群应用于盆栽试验，考察其对蓖麻铅锌摄取和转运的影响；分析蓖麻抗氧化系统响应及代谢组学差异，监测蓖麻全生命周期中不同生长阶段该菌群的演替及蓖麻根区环境的变化规律，从而较系统地揭示蓖麻与功能菌群相互作用的机理和内在联系。研究成果可为复合菌群强化植物异位修复重金属污染底泥方面提供科学依据和应用基础。

铅锌毒害与生物量小是影响Ricinus communis L.修复效果和经济利用价值的限制性因素，而改善根际环境可以有效降低重金属危害同时提高植物生物量，这与根际微生物菌群的功能密切相关。本课题在前期研究的基础，进一步优化构成复合功能菌群菌株的种类与比例，通过调整接种比例、碳源、氮源、pH、温度、培养基、培养时间等因素使之具有最佳的铅锌耐性、铅锌去除能力与植物促生活性，提升了重金属去除能力和植物促生性能。.将优选得到的复合功能菌群接种于蓖麻根部，考察了其对底泥中铅锌提取、转运能力、铅锌存赋形态、蓖麻生物量影响，结果表明，在低浓度铅锌胁迫下，处于Ricinus commumis L.萌发初期（0-8d），复合功能菌群的促生效果更为明显，特别是植物茎部生长最为显著；而在高浓度铅锌胁迫下，萌发初期，复合功能菌群仅显示出来较强的耐性，Ricinus commumis L.的成活率较高。在测试范围内，相同浓度梯度下，复合菌群组合主要促进了Ricinus commumis L.根毛的生长，可以使得根部总生物量提高12-26%。在蓖麻生长过程中监测复合功能菌群对蓖麻光合特性、抗氧化酶系统与叶片激素水平的影响，结果均表明，添加功能菌群后，对植物生理生化指标的影响主要体现在蓖麻生长早期，后期的影响不太明显。此外，数据记录表明，蓖麻生长后期，环境温度与光照条件可能也是较为重要的因素，后续研究需要加以考虑。.本课题还通过高通测序技术对蓖麻根际微生物群落结构及多样性进行了分析。总体上，铅锌胁迫下，芽孢杆菌纲与δ-变形菌纲相对丰度最大，占其细菌总量的较大部分，只有少部分细菌产生或消失，表明此类细菌群落具有一定的稳定性。在铅锌污染环境中，真菌类群十分单一，子囊菌门（Ascomycota）、粪壳菌纲（Sordariomycetes）、镰刀菌属（Fusarium）是群落在门、纲、属分类水平上的优势菌，曲霉属（Aspergillus）在铅锌胁迫后真菌总量中所占比重极显著高于无铅锌胁迫所占比重。由于研究时间有限，本研究仅对微生物的结构及多样性有了初步认知，但要了解铅锌胁迫对微生物群落结构以及添加复合功能菌群的影响机制，还需进一步深入研究。