典型封闭型海湾生境滩涂沉积物微生物群落结构及功能对沙蚕生态修复的响应

Sansha bay is a typical enclosed bay in China. It is the only inner bay for large yellow croaker spawning and the largest marine cage breeding base in China. Sansha bay also carries production sewage and living sewage of over 200 million people. Thus the problem of environmental pollution is increasing. Traditionally, the environmental quality is assessed by physical, chemical indicators or a number of large plants and animals, and visible small benthic organisms. Although microorganisms are more sensitive to environmental changes and are better indicators for environmental quality assessment, they have not been adopted due to the limit of detection means and people's poor understanding for them. One ongoing Ocean Public Welfare Research Project in our college is to restore the polluted mudflat sediments in Sansha bay using clamworm. With the convenience of sampling and data sharing of the ongoing project, and from the point of view of microbes, which play an important role in gulf ecosystem, the proposed project here aims to follow the microbial community structures and functions and their dynamics during the bioremediation through a combined approach involving clone libraries constructions, denaturing gradient gel electrophoresis(DGGE), Southern blot，biolog and high-throughput sequencing, etc. The relationship between microbes and environmental factors and people's repair activities will be analyzed, and the microbial indicators that can sensitively reflect environment changes will be found. The study will enable us to examine the environmental conditions of the typical closed bay habitat from a totally different new data and new point of view. The results revealed in this study will provide foundation for the optimization of the bioremediation measures and the improvement of environmental assessment indicators. The results will also provide data for further studies regarding the inshore ecosystem structure and function, the biogenic elements in biogeochemical cycles, and the pollutants transformation.

三沙湾是我国典型封闭型海湾，全国唯一内湾性大黄鱼产卵场及最大海水网箱养殖基地。三沙湾还承纳着周边200多万人口生产生活污水，环境污染问题日趋严重。传统的环境状况评估多采用物理、化学指标和大型动植物，及肉眼可见的小型底栖生物。而更能灵敏表征环境状况改变的微生物，由于检测手段的限制及人们对其知之甚少而未被采用。本项目从在生态系统结构和功能上起重要作用的微生物入手，借助本单位正承担相关海洋公益项目的便利条件，用构建克隆文库、DGGE、Southern杂交、biolog、高通量测序等手段，研究海湾生境沙蚕生态修复过程沉积物中活性微生物的群落结构、功能及动态变化，分析其与环境因子和修复行为间的关系，研究可灵敏反映环境状况变化的微生物参数，以全新数据和视角审视典型封闭型海湾生境环境状况。为优化修复措施、完善环评指标奠定基础，并为近岸海域生态系统结构功能、生源要素的生物地球化学循环及污染物的转化提供数据

三沙湾是我国典型封闭型海湾，环境污染问题日趋严重。传统的环境状况评估多采用理化指标、大型生物及肉眼可见的小型底栖生物指标，而更能灵敏表征环境变化的微生物未被采用。本项目综合运用传统分子生物学技术和高通量测序手段，初步阐明了三沙湾等滩涂沉积物中细菌、古菌、微型真核生物及氨氧化细菌、氨氧化古菌等的群落结构、动态变化、活性及其与环境因子和底栖动物扰动之间的关系。滩涂底泥中共有45个细菌门和5个古菌门。δ和γ-变形菌是优势类群，其他较丰富的类群包括拟杆菌、酸杆菌、浮霉状菌、绿弯菌和奇古菌等。普遍存在奇古菌MGI、泉古菌MCG和广古菌MBG-D等类群，MGI占优势地位。亚硝化单胞菌属和亚硝化螺菌属是氨氧化细菌主要类群，活性氨氧化古菌主要是海洋沉积物族群Cluster M。微型真核生物共分为10个类群，其中环节动物门、节足动物门为优势类群，腹毛动物门、线虫门为次优势类群。细菌对碳水化合物类、氨基酸类、聚合物类的利用率较高，对羧酸类、胺类以及其他化合物的利用率较低。与环境理化指标相比，微生物群落结构对季节变化和底栖动物的扰动响应迅速、明显，可以作为敏感指标指示环境变化。微生物的群落结构与采样时间/季节极显著相关,与pH和OrgN显著相关。播种底栖动物后一些有重要生态功能的细菌属丰度上升，而另一些属的丰度下降。底栖动物的扰动作用降低了氨氧化细菌的多样性，增加了古菌、活性氨氧化古菌和微型真核生物的多样性；刺激了MCG类群和氨氧化古菌Cluster1和3的生长，抑制了亚硝化单胞菌、古菌MGI类群、氨氧化古菌cluster2的生长；环节动物门和节足动物门所占比例增加，而腹毛动物门、丝足虫门和囊泡虫总门所占比例下降。沙蚕扰动显著刺激了细菌的活性，提高了细菌群落的碳源利用多样性，刺激了微生物对碳水化合物和氨基酸类碳源的利用，降低了对多聚物类碳源的利用。研究结果为将来开发海洋微型生物实时动态环境检测系统奠定了坚实的基础。