Effects of copper sulfate, hydrogen peroxide and N-phenyl-2-naphthylamine on oxidative stress and the expression of genes involved photosynthesis and microcystin disposition in Microcystis aeruginosa.

Algal blooms have been increasing in prevalence all over the world, destroying ecosystems and placing other organisms at risk. Chemical remediation is one of most important methods of controlling algal bloom formation. The effects of copper sulfate, hydrogen peroxide (H(2)O(2)) and N-phenyl-2-naphthylamine on photosynthesis-related and microcystin-related gene transcription and physiological changes of Microcystis aeruginosa were analyzed. The results suggest that transcription of psaB, psbD1 and rbcL was inhibited by the three algaecides, which blocked the electron transport chain, significantly enhanced reactive oxygen species (ROS) accumulation and overwhelmed the antioxidant system. The increase in ROS destroyed pigment synthesis and membrane integrity, which inhibited or killed the algal cells. Furthermore, H(2)O(2) treatment down-regulated mcyD transcription, which indicated a decrease in the microcystin level in the cells. Our results demonstrate that H(2)O(2) has the greatest potential as an algaecide because it not only inhibits algae growth but may reduce microcystin synthesis.