【作者】 刘腾腾；

【导师】 刘丽； 夏雪山；

【作者基本信息】 昆明理工大学 ， 生物化工， 2012， 硕士

【摘要】 目前全球海洋和淡水湖水体富营养化日益严重,导致蓝藻水华现象频繁发生,水域生态环境受到严重破坏。滇池是云贵高原最大的湖泊,水体富集营养化非常严重,近几年,政府对滇池投入大量资金进行治理、清除蓝藻,但还是频繁爆发蓝藻水华。作为特异性感染蓝藻的病毒,噬藻体在水生态系统中具有非常重要的作用,可作为蓝藻水华的控制因子,越来越多的研究针对噬藻体和蓝藻的遗传多样性以及它们之间的遗传关系。本研究以云南滇池为研究对象,每个月定时采取滇池的相同地点的水样,根据采样时的环境因素的检测以及水体的综合指数,初步研究滇池一年四个季节的蓝藻和噬藻体的遗传多样性,并研究滇池中蓝藻和其噬藻体的遗传关系以及它们之间的水平基因转移。每个月定时在滇池的相同地点采集水样,采集水样时检测水体的温度、pH值等环境指数,并结合滇池水体的综合指数,结果发现：滇池一年中的水体pH值变化不大,但一直维持在弱碱性；滇池的富集营养化主要是因为总氮含量超标,总磷有时也会超标,不同季节的滇池水华蓝藻现象有所不同。利用分子生物学方法对水样中的蓝藻和噬藻体进行实验研究,通过对滇池蓝藻的16S-23S rDNA ITS建立系统进化树来分析滇池蓝藻的遗传多样性,对滇池噬藻体的psbA基因序列分析,然后构建系统进化树研究分析滇池噬藻体的遗传多样性,结果发现：1、滇池蓝藻主要类型为微囊藻属,主要有铜绿微囊藻、水华微囊藻、惠氏微囊藻等,也含有少量的鱼腥藻和念珠藻,表明了滇池蓝藻丰富的遗传多样性,不同季节的蓝藻类型有所差异,可能由于温度等环境因素的变化导致,2、滇池噬藻体的序列分布在系统进化树的许多分支,显示了丰富的遗传多样性,噬藻体主要类型为铜绿微囊藻的噬藻体,也有少许的聚球藻的噬藻体,并且不同季节的噬藻体类型差异很大。分别扩增滇池蓝藻和噬藻体的psbA基因,然后对同一时间的蓝藻和噬藻体的psbA序列构建系统进化树,在进化树中分析蓝藻和噬藻体之间的遗传关系以及基因转移。结果发现：尽管系统进化树中确信值比较低,推测噬藻体的光合作用基因最初来源于宿主蓝藻中,噬藻体能介导不同蓝藻之间的光合作用基因的交换,滇池中的蓝藻与噬藻体频繁的进行着光合作用基因的水平基因转移。通过以上的研究,初步了解了滇池的蓝藻和噬藻体的主要种类以及遗传多样性,并初步分析了滇池中的噬藻体和其宿主蓝藻的光合作用基因的水平基因转移,能更好的研究蓝藻和噬藻体的进化史,也为进一步研究噬藻体在治理蓝藻提供了一定的理论证据。更多还原

【Abstract】 At present the eutrophication of waterbodies worldwide becoming more and more serious. The incidence of cyanobacterial blooms is increasing, which pose serious risks for human and animal health, aquatic ecosystem sustainability. Dianchi Lake is the largest lake in the Yunnan-Guizhou Plateau, a lake of serious eutrophication. In recent years, the government invested the massive funds to improve the water quality, but cyanobacterial blooms still outbreaking frequently. As a specific infected viruse of cyanobacteria, cyanophage has a very important role in aquatic ecosystems and can be use as a controlling factor in cyanobacterial blooms, which was considered as a promising biological algicide. More and more research has been in the phylogenetic diversity of cyanophages and cyanobacteria and their genetic relationship.In this study we take the Dianchi Lake as our object, collecting water samples in the same place every month.According to environmental factors and composite index of water bodies,we have a preliminary study of genetic diversity and the genetic relationship and horizontal gene transfer between cyanobacteria and cyanophage.We collect water samples in Dianchi Lake at the same location every monthl and measure the water temperature and pH value and the other biochemical parameters. Combinaing the composite index of the Dianchi Lake, we found that:the pH value in Dianchi Lake changed little in a year, but has remained at a very high value; the entrophication in Dianchi Lake was mainly due to excessive total nitrogen content, andtotal phosphorus sometimes excessive; the cyanobacteria phenomenon in Dianchi Lake was different as season changing.We study the cyanobacteria and cyanophage in water samples in use of molecular biology, establishing the phylogenetic tree of16S-23SrRNA ITS to analyze the genetic diversity of the cyanobacteria, and combinaing the the phylogenetic tree of psbA to analyze the genetic diversity of cnanophage.we found that:1、the main type of cyanobacteria was Microcystis, included Microcystis aeruginosa, Bloom Microcystis, Microcystis wesenbergii, and a small amounts of Anabaena and Nostoc, indicating that the rich genetic diversity of cyanobacteria in Dianchi Lake. The temperature and other environmental factors changed in different seasons resulted in different type of cyanobacteria.2、The cyanophage sequences located in the many branches of the phylogenetic tree, showing the rich genetic diversity of cyanophage in Dianchi Lake, the main type of cyanophage was cyanophage of Microcystis aeruginosa snd little Synechococcus cyanophage and the type of cyanophage was great changed in different seasons.The cyanobacteria and cyanophage psbA gene was amplified and established the phylogenetic tree of cyanobacteria and cyanophage psbA at the same time.According to the phylogenetic tree, we analysised the genetic relationship and gene transfer between cyanobacteria and cyanophage. The result showed that:the psbA gene in the cyanophage was originated from the cyanobacteria as the convinced values in phylogenetic tree was relatively low, we concluded that the cyanophage can mediate the exchange of psbA in different cyanobacteria.The horizontal gene transfer of psbA in cyanobacteria and cyanophage occurred frequently.Through the above research, we have a preliminary understanding in the main types and the genetic diversity of cyanobacteria and cyanophage, and have a preliminary analysis of the horizontal gene transfer of psbA between cyanobacteria and cyanophage in the Dianchi Lake. The result in this study can make us have a better research on the evolutionary history of the cyanobacteria and cyanophage, and provide theory of evidence in the cyanophage governancing cyanobacteria.更多还原