水环境中微囊藻毒素的生物降解

微囊藻毒素在水环境中的生物降解是决定其环境归趋和影响其毒性的重要因素。本文综述了水细菌、鱼类、水生植物、水生无脊椎动物、浮游动物等水生生物对微囊藻毒素生物降解方面的研究进展。目前报道的微囊藻毒素降解菌有鞘氨醇单胞菌、铜绿假单胞菌和青枯菌。鞘氨醇单胞菌和铜绿假单胞菌分别以微囊藻毒素酶和碱性蛋白酶降解毒素，青枯菌降解机理未明；而鱼类、水生植物、水生无脊椎动物、浮游动物等水生生物主要通过谷胱甘肽S-转移酶催化形成低毒性的微囊藻毒素-谷胱甘肽结合物进行转化。本文还对水环境微囊藻毒素的生物修复方式进行了初步的探讨。

Biodegradation of microcystin in aquatic environment

Biodegradation is the key factor that determines the fate of microcystin in aquatic ecosystem and its toxicological effects on aquatic organisms. This paper reviewed the studies on biodegradation of microcystin by aquatic bacteria, plants, invertebrates and fishes. Different groups of aquatic organisms showed different pathways of microcystin degradation. Aquatic bacteria Sphingomonas sp, Pseudomonas aeruginosa and Ralstonia solanacearum had the ability of biodegradation of microcystin. Degradation of microcystin-LR in Sphingomonas sp was carried out by at least three intracellular hydrolytic enzymes, one of them was termed microcystinase. While the degradation of microcystin in Pseudomonas aeruginosa was carried out by alkaline protease. The pathway of microcystin degradation in Ralstonia solanacearum was unclear. For aquatic plants, invertebrates and fishes, microcystin was mainly biotransformed into a conjugate product with GSH, which is catalyzed by glutathione S-transferases. This paper also discussed the bioremediation strategies of microcystin in aquatic environments.