白腐真菌强化修复新烟碱农药污染洞庭湖湿地的作用机制及微生物群落响应研究

The pollution caused by neonicotiniods is a major threat to ecological environment in wetland and human health, which is one of the most urgent problems. It was confirmed that white-rot fungi can degrade neonicotiniods. However, the remediation efficiency and related mechanisms in real wetland environment are unclear. In this project, Dongting Lake will be selected as the research area. White-rot fungi will be applied to accelerate neonicotiniods degradation in wetland of Dongting Lake. On the base of understanding the effects of remediation pattern and the main wetland soil properties on white-rot fungi bioaugmentation bioremediation, researches will be focused on investigating the role of functional enzymes in white-rot fungi as well as the degradation pathway and toxicity of the degraded products of neonicotioids during the bioremediation process. Moreover, the native microbial community structure and metabolic ability to white-rot fungi bioaugmentation will be also analyzed to reveal the molecular response mechanism of microbial community. Finally, the remediation process will be understood scientifically from the two aspects of remediation behavior and microbial community response associated with soil micro-environmental and self-purification. The study could provide a theoretical basis and references for development of white-rot fungi-based technology in remediation of neonicotiniods contaminated wetland, which also benefit to the effective treatment of neonicotiniods contaminated wetland and the improvement of micro-ecosystem.

新烟碱农药造成的污染威胁着湿地生态环境及人类健康，是亟待解决的问题。目前已证实白腐真菌能有效降解新烟碱农药，但其在湿地实际环境中的修复效果及其机理尚不清楚。本项目拟以洞庭湖为研究区域，采用白腐真菌强化修复，加速新烟碱农药在湿地中的降解，在掌握白腐真菌修复实施方式及湿地土壤主要参数对修复效果影响的基础上，重点考察修复过程中白腐真菌功能酶的作用特征、新烟碱农药降解途径及产物的生物毒性，剖析白腐真菌作用下土著微生物群落结构及代谢功能变化规律，揭示微生物群落的分子响应机制，最终从白腐真菌修复的行为机理和引起微生物群落响应而影响湿地土壤微环境和自净能力这两个层面，来洞悉白腐真菌修复新烟碱污染湿地的全过程。本项目有望为发展白腐真菌技术有效用于新烟碱农药污染修复的方法提供理论依据和方法参考，有利于实现新烟碱农药污染湿地的有效处理和微生态环境改善。

本项目针对新烟碱农药大量使用引起的湿地污染和生态风险问题，采用环境功能微生物—白腐真菌进行强化修复，系统研究了白腐真菌对新烟碱农药污染湿地的强化修复作用机制及其微生物群落响应。本项目研究结果为发展白腐真菌技术有效应用于有机污染湿地修复的方法提供理论依据和方法参考，同时有利于实现新烟碱农药污染环境的有效处理和微生态环境改善。主要研究结果如下：.（1）白腐真菌对新烟碱农药展现出优秀的降解能力，能分别在7天和25天左右将10 mg/L的吡虫啉和噻虫嗪降解90%以上；白腐真菌驱动醌氧化还原的生物高级氧化过程促进羟基自由基的产生及功能酶活性可增强其对新烟碱农药的降解能力，此过程需要铁/锰的参与。.（2）木质素过氧化物酶和锰过氧化物酶在存在吡虫啉作底物时活性增高；吡虫啉分子与LiP和MnP酶主要通过范德华力驱动结合，形成了稳定的空间构象，有利于酶促氧化还原；MnP可能主要参与了吡虫啉分子的羟基化代谢过程;细胞色素P450在菌体降解噻虫嗪过程发挥重要作用。.（3）黄孢原毛平革菌以孢子态和秸秆预发酵形式接种对湿地土壤中的吡虫啉和噻虫嗪降解效果最佳；修复过程中，土壤有机碳含量降低、pH升高；白腐真菌强化处理增加了土壤蔗糖酶活性、降低了脲酶活性，对过氧化氢酶活性影响不大。.（4）白腐真菌对新烟碱农药的降解主要通过硝基还原、脱硝、脱氯、羟基化、C-N键断裂及开环等过程；基于产物毒性预测、典型微生物生长测试、种子萌发实验等，白腐真菌能一定程度上实现新烟碱农药的脱毒，各产物的毒性与受试生物有关；在添加白腐真菌的部分土壤中发现了异于土著微生物条件下的噻虫嗪的代谢产物。.（5）添加的白腐真菌能在湿地土壤中定殖并发挥功能；土壤微生物群落的多样性和丰度变化与白腐真菌的添加形式有关；孢子态接种的白腐真菌土壤微生物结构与对照组相似度最高；接种白腐真菌增强了土壤中有关异生物质降解和代谢的途径功能及相应的基因丰度，实现了对新烟碱农药的强化去除。