Quantification of microcystin-producing and non-microcystin producing Microcystis populations during the 2009 and 2010 blooms in Lake Taihu using quantitative real-time PCR  

作　　者：Daming Li Fanxiang Kong Xiaoli Shi Linlin Ye Yang Yu Zhen Yang 

机构地区：[1]State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China [2]Graduate University of Chinese Academy of Sciences, Beijing 100049, China

出　　处：《Journal of Environmental Sciences》2012年第2期284-290,共7页环境科学学报（英文版）

基　　金：supported by the National Basic Research Program (973) of China (No. 2008CB418000)

摘　　要：Lake Taihu,a large,shallow hypertrophic freshwater lake in eastern China,has experienced lake-wide toxic cyanobacterial blooms annually during summer season in the past decades.Spatial changes in the abundance of hepatotoxin microcystin-producing and nonmicrocystin producing Microcystis populations were investigated in the lake in August of 2009 and 2010.To monitor the densities of the total Microcystis population and the potential microcystin-producing subpopulation,we used a quantitative real-time PCR assay targeting the phycocyanin intergenic spacer（PC-IGS） and the microcystin synthetase gene（mcyD）,respectively.On the basis of quantification by real-time PCR analysis,the abundance of potential toxic Microcystis genotypes and the ratio of the mcyD subpopulation to the total Microcystis varied significantly,from 4.08×104 to 5.22×107 copies/mL,from 5.7% to 65.8%,respectively.Correlation analysis showed a strong positive relationship between chlorophyll-a,toxic Microcystis and total Microcystis;the abundance of toxic Microcystis correlated positively with total phosphorus and ortho-phosphate concentrations,but negatively with TN：TP ratio and nitrate concentrations.Meanwhile the proportion of potential toxic genotypes within Microcystis population showed positive correlation with total phosphorus and ortho-phosphate concentrations.Our data suggest that increased phosphorus loading may be a significant factor promoting the occurrence of toxic Microcystis bloom in Lake Taihu.Lake Taihu,a large,shallow hypertrophic freshwater lake in eastern China,has experienced lake-wide toxic cyanobacterial blooms annually during summer season in the past decades.Spatial changes in the abundance of hepatotoxin microcystin-producing and nonmicrocystin producing Microcystis populations were investigated in the lake in August of 2009 and 2010.To monitor the densities of the total Microcystis population and the potential microcystin-producing subpopulation,we used a quantitative real-time PCR assay targeting the phycocyanin intergenic spacer（PC-IGS） and the microcystin synthetase gene（mcyD）,respectively.On the basis of quantification by real-time PCR analysis,the abundance of potential toxic Microcystis genotypes and the ratio of the mcyD subpopulation to the total Microcystis varied significantly,from 4.08×104 to 5.22×107 copies/mL,from 5.7% to 65.8%,respectively.Correlation analysis showed a strong positive relationship between chlorophyll-a,toxic Microcystis and total Microcystis;the abundance of toxic Microcystis correlated positively with total phosphorus and ortho-phosphate concentrations,but negatively with TN：TP ratio and nitrate concentrations.Meanwhile the proportion of potential toxic genotypes within Microcystis population showed positive correlation with total phosphorus and ortho-phosphate concentrations.Our data suggest that increased phosphorus loading may be a significant factor promoting the occurrence of toxic Microcystis bloom in Lake Taihu.

关 键 词：microcystin-producing Microcystis real-time PCR toxic cyanobacterial bloom microcystin synthetase gene cluster 

分 类 号：X52[环境科学与工程—环境工程] Q75[生物学—分子生物学]