大型海藻龙须菜对重金属镉胁迫的响应

研究了大型海藻龙须菜在不同培养介质中的生长状况及对不同浓度重金属镉（Cd ）胁迫的响应，并探讨了磷（P）、乙二胺四乙酸（EDTA）对龙须菜生理生化特性的影响。结果表明，在未加P和EDTA的天然海水组，随Cd浓度升高，龙须菜生长逐渐受到抑制，藻体藻红素 (PE)含量明显减少，叶绿素a (Chla) 和可溶性蛋白含量总体呈下降趋势，但变化幅度均不大，过氧化物酶（POD）活性出现先上升后下降趋势，并在Cd浓度为4.5mg/L时达到最大值。当培养介质加了P和EDTA，随Cd浓度升高，龙须菜出现先增长随后逐渐受到抑制，叶绿素a和可溶性蛋白含量总体呈先上升后下降趋势，其中Chla在Cd浓度为3.0 mg/L或4.5 mg/L时达到最大值，POD活性在培养初期总体呈上升趋势，而在大于6 d后则逐渐下降，天然海水+EDTA组在培养时间小于6 d，POD活性总体呈上升趋势，当培养时间大于6 d且Cd浓度大于4.5 mg/L时，POD活性又开始逐渐下降。研究显示龙须菜对低浓度Cd胁迫具有一定的抵抗能力，且Cd对龙须菜的毒害受时间和浓度双重因子的制约；营养元素P和解毒络合剂EDTA对龙须菜抵抗重金属Cd胁迫有一定促进作用。

Response of Seaweed Gracilaria Lemaneiformis to Cadmium Stress

The growth and response of Gracilaria lemaneiformis to Cadmium stress in different cultivation conditions were studied, the effects of physiological and biochemical characteristics of G. lemaneiformis were explored while appending phosphate or ethylenediaminetetra-acetic acid (EDTA) into the cultured medium. The results showed that the growth of G. lemaneiformis was inhabited gradually with the increase of the content of Cadmium, the contents of phycoerythrin, Chlorophyll and soluble protein decreased, the activity of peroxidase increased at first reached the maximum value at 4.5 mg/L of Cadmium, and then dropped. While appending phosphate or EDTA into different cultured medium, the growth of G. lemaneiformis, the contents of Chlorophyll and soluble protein increased and dropped gradually with the increase of the content of Cadmium, the activity of peroxidase increased during the initial days and decreased with the prolong of time (>6 days). All results indicated that the resistance of G. lemaneiformis to Cadmium stress in low content environment was strong, the poisons of Cadmium was restricted to the factors of time and its concentration; meanwhile, phosphate and EDTA could benefit G. lemaneiformis to resist Cadmium stress to some degree.