饮用水源水中微囊藻毒素生物滤池降解机制研究

The effective removal of microcystins (MC) for drinking water treatment is still challenging. This program aims to explore an effective treatment method for MC-polluted drinking water, and to disclose the biodegradation mechanism of microcystins by biological aerated filter (BAF). We have isolated several MC-degrading bacteria and algaecidal bacteria from the sediments of Taihu Lake, the intestines of loach and silver carp, and the dominant bacteria for MC degradation has been enriched. The removal of extracellular dissolved MC and algae by BAF will be studied. The interchange of intracellular and extracellular MC of algae trapped by BAF will also be studied. Intermediates and final products of MC degradation will be tested by HPLC-ESI/MS and NMR. Then the possible degradation pathways can be proposed and site that susceptible to bio-oxidation can alsobe found. Meanwhile, toxicity test using Caenorhabditis elegans as the model organism will be carried out to study the detoxification effect of MC and to confirm the toxicity of final products. The PCR-DGGE and T-RFLP technologies will be employed to investigate successional rules of microbial communities in the process of MC degradation and to clarify the synergies and cometabolism characteristics between the filter media and biofilm communities. This proposed program will provide theoretical basis and methodological guidance for the reasonable selection of eutrophic water treatment processes and the obtainment of safe drinking water from water source polluted by eutrophic algaes.

针对饮用水中MC难以有效去除这一难题，探索饮用水中MC污染有效处理方法与降解机制，利用我们已获得的从太湖河浜底泥、泥鳅和白鲢鱼肠中成功地分离的MC降解菌和溶藻细菌为菌种来源，采用优势菌种内循环生物挂膜法在水厂预处理富营养化水源水的曝气生物滤池中培养能高效降解MC的生物膜，在此基础上研究BAF滤池对溶解态胞外MC和藻体的去除特性及滤池中截留藻体的胞内外MC转换特性；采用HPLC-ESI/MS和NMR跟踪测试MC降解中间产物和终产物单体结构，推测可能的降解路径和易被生物氧化的位点，同时以秀丽隐杆线虫为模式生物进行毒性试验，推测降解过程对MC的脱毒效果，达到确认终产物的毒性。采用PCR-DGGE和T-RFLP技术研究生物膜在降解MC过程中微生物种群的演替规律，弄清滤料和生物膜群落间的协同作用和共代谢特征。为从富营养化藻类污染水源水制取安全饮用水，合理选择富营养化水处理工艺提供理论依据和方法指导。

项目针对饮用水源地藻类暴发和藻毒素超标污染等问题，优化曝气生物滤池（BAF）预处理微污染水源水滤料类型和级配。从太湖底泥、芦苇及鱼内脏中成功筛选得到4株高效溶藻和藻毒素降解菌，同时利用高效溶藻菌R1与MC降解菌JZ-4构建双效工程菌Y-1。所获菌种制备的菌剂可高效强化BAF对藻类和藻毒素去除，揭示了BAF对溶解状胞外MC和藻体的去除特性及滤池中截留藻体的胞内外MC转换特性。采用PCR-DGGE和T-RFLP研究生物膜在降解MC过程中微生物种群的演替规律，弄清了滤料表面生物膜群落结构、微生物多样性，阐明了溶藻、MC降解具有协同作用和共代谢特征。基于三维荧光光谱和红外吸收光谱探明了BAF控藻及去MC-LR途径。基于发光细菌毒性检测技术和USEPA非致癌健康风险评价模型，构建了菌剂强化协同BAF预处理微污染水源水的急性毒性和MC-LR非致癌健康风险评价体系，测定MC降解过程中的脱毒效应，证实了菌剂强化BAF工艺可消除含MC饮用水源水的急性毒性和致突变风险。. 项目发表论文16篇，申请发明专利7项，培养研究生8名，均超额完成任务。