芦苇化感物质EMA对铜绿微囊藻生长及藻毒素产生和释放的影响

研究了芦苇化感物质2-甲基乙酰乙酸乙酯（ethyl-2-methylacetoacetate,EMA）对铜绿微囊藻PCC7806的生长抑制特性以及对微囊藻毒素MC-LR产生和释放的影响.结果表明,EMA在培养1周内对铜绿微囊藻PCC7806具有较强的抑制作用,EC_50,7d值为2.0 mg·L^-1,但EMA的抑制效果随时间的延长而减弱.整个培养期间,EMA对MC-LR的胞外释放无显著影响.培养7　d后,单位藻细胞内MC-LR的含量随EMA浓度的增加而升高,EMA投加浓度为1.5　mg·L^-1时,单位藻细胞MC-LR的含量为25 ng·(10⁶个)^-1,比对照组增加了39%.但单位体积培养液中MC-LR总量（胞内和胞外的总和）随EMA浓度增加先略微升高后显著降低,EMA投加浓度为3 mg·L^-1时,培养液中MC-LR胞内胞外总量为28 μg·L^-1,约为对照组的一半;16　d后,EMA对单个细胞内MC-LR的含量以及MC-LR总量均无显著影响.

Effects of Allelochemical EMA from Reed on the Production and Release of Cyanotoxins in Microcystis aeruginosa

The growth inhibition of ethyl-2-methylacetoacetate (EMA) isolated from common reed (Phragmites australis Trin. or Phragmites communis Trin.) on the growth of Microcystis aeruginosa PCC7806 was investigated and the intracellular and extracellular concentration of cyanotoxin (MC-LR) after treatment of EMA were tested. The experimental results indicated that EMA has significant inhibitory effect on the growth of M. aeruginosa PCC7806, and the value of EC(50,7d) was 2.0 mg x L(-1). However, the inhibition declined with the cultivation time. During the whole cultivation period, EMA showed no significant effect on the release of MC-LR from cells to the culture. After 7 days, the amount of intracellular MC-LR per cell unit increased with the increasing of EMA concentration. The amount of MC-LR per cell unit was 25 ng x (10(6) cells)(-1) after the treatment with 1.5 mg x L(-1) EMA, which was increased by 39% compared with the control. The total MC-LR production (including intracellular and extracellular MC-LR) first slightly increased and then decreased significantly with the increase of EMA concentration. After the treatment with 3 mg x L(-1) EMA, the total MC-LR production was 28 microg x L(-1) (only half of that in the control). After 16 days, EMA showed no significant effect on both the amount of MC-LR per cell and the total MC-LR production.