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研究报告

Effect of copper stress on cell proliferation and production of microcystin Microcystis aeruginosa

基金项目：国家水体污染控制与治理科技重大专项子课题（No.2012ZX07313001-002）；陕西省青年科技新星项目（No.2013KJXX-55）

摘要：以硝酸盐和磷酸氢盐为主要氮源和磷源，通过测定一定初始氮、磷条件下不同Cu²⁺浓度培养液中藻密度及藻毒素浓度来研究微量元素Cu对铜绿微囊藻生长的影响.结果表明：当Cu²⁺浓度为1和10 μg·L^-1时，藻细胞的生长情况最好，藻密度取得所有浓度梯度中最大值；当Cu²⁺浓度为1 μg·L^-1时，藻细胞产毒素总量最大；Cu²⁺严重缺乏（0.01 μg·L^-1）和过量（100 μg·L^-1）时，藻毒素的合成均受到严重抑制.Cu²⁺浓度变化影响铜绿微囊藻对硝氮的利用效率，当Cu²⁺浓度为0.01、0.1及100 μg·L^-1时，氮元素的利用效率都相对较低.细胞比增长率与单细胞产毒量之间的相关性分析及线性拟合结果表明，单细胞产毒素量与细胞比增长率之间存在很好的线性关系：在Cu²⁺浓度处于0.01~10 μg·L^-1范围内，二者表现为正相关；Cu过量时（100 μg·L^-1），表现为负相关，依据此结果可通过比增长率来预测单细胞的产毒素水平.

Abstract：The effect of Cu²⁺ stress on the cell proliferation and production of microcystin Microcystis (M.) aeruginosa were studied by batch experiments. Nitrate and hydrophosphate were used as the main source of nitrogen and phosphorous. Cell density and concentration of total microcystin under different Cu²⁺ concentrations (C_Cu) were measured. The results showed that M. aeruginosa presented the optimum growth condition when C_Cu was 1 μg·L^-1 and 10 μg·L^-1, and the cell density acquired the maximum values under these two C_Cu concentrations. Furthermore, the microcystin concentration reached the maximum value at C_Cu of 1 μg·L^-1. In contrast, microcystin production was significantly inhibited when Cu was deficient (0.01 μg·L^-1) or excess (100 μg·L^-1) due to limited capacity of M. aeruginosa for nitrogen uptake under an extremely low or high C_Cu. The cellular microcystin and specific growth rate were linearly dependent on each other, which presented positive correlation when C_Cu was in the range of 0.01 to 10 μg·L^-1 while negative correlation when C_Cu was excess (100 μg·L^-1) and as a result the microcystin production was able to be deduced by specific growth rate.