Enantioselective changes in oxidative stress and toxin release in Microcystis aeruginosa exposed to chiral herbicide diclofop acid.
Enantioselective oxidative stress and toxin release from Microcystis aeruginosa after exposure to the chiral herbicide diclofop acid were investigated. Racemic diclofop acid, R-diclofop acid and S-diclofop acid induced reactive oxygen species (ROS) generation, increased the concentration of malondialdehyde (MDA), enhanced the activity of superoxide dismutase (SOD) and triggered toxin release in M. aeruginosa to varying degrees. The increase in MDA concentration and SOD activity in M. aeruginosa occurred sooner after exposure to diclofop acid than when the cyanobacteria was exposed to either the R- and the S-enantiomer. In addition, enantioselective toxicity of the enantiomers was observed. The R-enantiomer trigged more ROS generation, more SOD activity and more toxin synthesis and release in M. aeruginosa cells than the S-enantiomer. Diclofop acid and its R-enantiomer may collapse the transmembrane proton gradient and destroy the cell membrane through lipid peroxidation and free radical oxidation, whereas the S-enantiomer did not demonstrate such action. R-diclofop acid inhibits the growth of M. aeruginosa in the early stage, but ultimately induced greater toxin release, which has a deleterious effect on the water column. These results indicate that more comprehensive study is needed to determine the environmental safety of the enantiomers, and application of chiral pesticides requires more direct supervision and training. Additionally, lifecycle analysis of chiral pollutants in aquatic system needs more attention to aide in the environmental assessment of chiral pesticides.
School of Chemical and Environmental Engineering, Shanghai Institute of Technology, Shanghai 201418, China; MOE Key Lab of Environmental Remediation and Ecosystem Health, College of Natural Research and Environmental Sciences, Zhejiang University, Hangzhou 310058, China.
Jing
J
Ye
Department of Environmental Science, East China Normal University, Shanghai 200241, China.
Ying
Y
Zhang
School of Urban Development and Environment Engineering, Shanghai Second Polytechnic University, Shanghai 201209, China.
Shengwen
S
Chen
School of Chemical and Environmental Engineering, Shanghai Institute of Technology, Shanghai 201418, China.
Chaonan
C
Liu
School of Chemical and Environmental Engineering, Shanghai Institute of Technology, Shanghai 201418, China.
Yongqiang
Y
Zhu
MOE Key Lab of Environmental Remediation and Ecosystem Health, College of Natural Research and Environmental Sciences, Zhejiang University, Hangzhou 310058, China. Electronic address: wliu@zju.edu.cn.
Weiping
W
Liu
D008387:Marine Toxins; D052998:Microcystins / Q000032:analysis / Q000378:metabolism*; D046931:Microcystis / Q000187:drug effects*; D018384:Oxidative Stress / Q000187:drug effects*; D010647:Phenyl Ethers / Q000633:toxicity*; D011422:Propionates / Q000633:toxicity*; D017382:Reactive Oxygen Species / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000633:toxicity*
C529887:2-(4-(2,4-dichlorophenoxy)phenoxy)propionic acid; D008387:Marine Toxins; D052998:Microcystins; D010647:Phenyl Ethers; D011422:Propionates; D017382:Reactive Oxygen Species; D014874:Water Pollutants, Chemical; D013482:Superoxide Dismutase; C057862:cyanoginosin LR
Diclofop acid; Enantioselectivity; Environmental toxicology; Toxin release