敌敌畏对鲫鱼的急性毒性及类球红细菌的解毒作用

Acute Toxicity of Dichlorvos to Carassius auratus and the Detoxification by Rhodobacter sphaeroides

敌敌畏是使用最为广泛的有机磷农药之一,具有较高的水溶性,对水生动物的危害较大.为初步探讨水体中敌敌畏降解菌对中毒鱼类的解毒作用,测定了敌敌畏对鲫鱼(Carassius auratus)幼鱼的急性毒性,调查了一株敌敌畏高效降解菌——类球红细菌(Rhodobacter sphaeroides)的解毒作用.结果表明:敌敌畏对鲫鱼幼鱼48、72、96h的LC50分别为45.1、30.4、23.3mg·L-1,安全浓度为2.3mg·L-1,属低毒农药.在不同敌敌畏暴露浓度的养鱼水中添加类球红细菌(5×107CFU·mL-1)可以显著降低鲫鱼的死亡率,20mg·L-1和35mg·L-1敌敌畏暴露浓度下,鲫鱼96h死亡率分别由40%和100%降低至0和15%;利用液相色谱检测了敌敌畏在添加和不添加类球红细菌的养鱼水中的降解规律,发现类球红细菌的解毒作用主要是对水中敌敌畏的快速降解,降解过程中没有积累有毒代谢产物.

Dichlorvos（DDVP）is one of the most widely used organophosphate insecticides, with high water-solubility and high risk to aquatic animals. In order to explore the detoxification of DDVP by degrading strain to poisoned fish, the acute toxicity of DDVP to Carassius auratus was determined, and the detoxifcation by a strain of Rhodobacter sphaeroides, which has high degradation capability to DDVP was investigated. Results showed that the half lethal concentration （LC50）of DDVP to C. auratus at 48, 72 and 96h were 45.1, 30.4 and 23.3mg·L-1, respectively. The safe concentration was 2.3mg·L-1. R. sphaeroides （5 ×107CFU·mL-1）could reduce the mortality of C. auratus significantly. Adding R. sphaeroides （5 ×107CFU·mL-1）to 20mg·L-1 and 35mg·L-1 DDVP treatments reduced C. auratus mortality significantly from 40% and 100% to 0 and 15%, respectively at 96h. The degradation of DDVP was detected by HPLC in fish water with and without R. sphaeroides, respectively. The result showed that the detoxification by R. sphaeroides was mainly due to the rapid degradation of DDVP by R. sphaeroides. There were no toxic degradation products in degradation process.