【摘要】 采用基于mcyA基因的PCR-DGGE和定量PCR分子技术,研究了太湖夏季蓝藻水华期间不同湖区水柱和表层底泥中产毒蓝藻基因型组成和种群丰度,同时利用高效液相色谱(HPLC)法测定了水体中微囊藻毒素(Microcystin,MC)3种异构体(MC-LR、MC-YR、MC-RR)的浓度,为太湖蓝藻水华治理及其生态风险评估提供基础资料。结果表明,太湖产毒蓝藻有12种主要的基因型,不同湖区水体和底泥中基因型组成及其丰度存在差异,水体中基因型多样性高于底泥,所有样品中占优势的基因型是一致的,富营养化水平对产毒蓝藻群落结构有一定的影响。同时发现,水体中不同湖区产毒藻细胞种群丰度差异显著,富营养化水平高的湖区种群丰度也较高,底泥中产毒藻细胞种群丰度波动较小。水体中微囊藻毒素3种异构体中MC-LR浓度最高,其所占比例在湖区间有一定的差异,总微囊藻毒素浓度范围为0.54～1.08μg·L-1,部分湖区微囊藻毒素浓度超过WHO推荐的安全浓度阈值(<1.0μg·L-1),必须引起足够重视。更多还原

【Abstract】 The community structures and abundances of microcystin-producing cyanobacteria in water column and surface sediment in Tai Lake were investigated using denaturing gradient gel electrophoresis(DGGE) and quantitative real time PCR(qPCR) techniques based on mcyA gene. Meanwhile, we measured the concentrations of three microcystin variants(microcystin-LR, microcystin-YR and microcystin-RR) in water body by high performance liquid chromatography(HPLC). DGGE profiles showed that there were 12 main mcyA genotypes in the toxic cyanobacteria of Tai Lake. The composition of microcystin-producing genotypes and the abundance of each genotype differ spatially in water column and surface sediment. Although mcyA genotype community was more diverse in water body than in sediment, the dominant mcyA genotype in all samples was the same. In addition, microcystin-producing community was affected by the status of eutrophication. qPCR data showed significant spatial variation in the abundance of toxic cyanobacteria in water column, which is high in the water with high status of eutrophication. However, this was not the case for sediment. Microcystin-LR is the main toxin of Microcystis, and its proportion to the total concentration of dissolved microcystin is not constant. The total concentration of microcystin ranged from 0.54 to 1.08 μg·L-1, exceeding the guideline value(1.0 μg·L-1 set by WHO) in some lake areas. This is the first study on the spatial changes in the community structure and abundance of microcystin-producing cyanobacteria in water column and surface sediment of Tai Lake, and our results can be used for assessing the ecological risk as well as the management of water bloom.更多还原