南京玄武湖微囊藻水华种类组成的研究

Composition of Microcystis Species of the Cyanobacterial Bloom in Xuanwu Lake of Nanjing

2005-08～2006-10采集蓝藻水华样品,通过形态学特征和ITS序列分子标记的方法对南京玄武湖水华的优势种类进行了鉴定.结果表明,玄武湖水华主要由微囊藻构成,通过形态特征鉴定主要种类为铜绿微囊藻（M.aeruginosa）、M.novacekii和惠氏微囊藻（M.wesenbergii）.3种藻的生物量在水华中的相对比例分别为30%～45%、35%～40%和10%～15%.采用分子标记的方法对2种优势种类进行了分子鉴定.PCR扩增ITS序列并进行测序,通过基因序列比对和基于ITS序列的系统发生树分析,进一步确定了优势种类为M.aeruginosa和M.novacekii;通过检测产毒基因mcyB来确认2株优势微囊藻的产毒特性,PCR扩增结果均出现了大约为780bp的特异性片段,表明这2种藻均为产毒种.对水华提取物的高效液相色谱（HPLC）测定表明,玄武湖水华中微囊藻毒素的种类主要是MC-LR和MC-RR.

The aim of the present study was to clarify the community composition of cyanobacterial bloom in Xuanwu Lake of Nanjing city. The Microcystis colonies in cyanobacterial blooms sampled from Xuanwu Lake during August 2005 and September 2006 were identified by morphological characteristics and internal transcribed spacer sequence （ITS）. The results indicated that the bloom was composed mainly by Microcystis aeruginosa, M.novacekii and M. wesenbergii. The biomass percentage of them was 30% - 45%, 35% - 40% and 10% 15%, respectively. ITS of two dominant Microcystis strains were amplified by PCR and sequenced to identify their species. The analysis of ITS sequences and the ITS phylogenetic tree demonstrated that the two dominant species should be M. aeruginosa and M.novacekii. A microcystin-producing gene mcyB was detected to test toxic strain. A unique product of approximately 780 bp was amplified in two dominant strains. It indicated that beth of them were of microcystin-producing genotype. High performance liquid chromatography （HPLC） analysis showed that the toxins in the native bloom biomass were mainly MC-LR and MC-RR.