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| Inhibitory effects of a-linolenic acid on the red tide microalgae Heterosigma akashiwo |
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Abstract The inhibitory effects of a-linolenic acid on the red tide microalgae Heterosigma akashiwo were studied. The possible algicidal mechanism was investigated through the membrane permeability, antioxidant enzymes, and photosynthesis of the microalgae cells. Results showed that the growth of H. akashiwo was inhibited obviously by high concentrations of a-linolenic acid. The 7-day IC50 was 2.4μL/L. The membrane permeability was destroyed by the a-linolenic acid treatment with the intracellular concentration of Na+, K+, Mg2+ and Ca2+ decreased significantly after 36h. The soluble protein content of algal cells decreased during the experimental process with the antioxidant enzymes superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) content elevated at 8h, then decreased significantly gradually until 24h, and finally lower than the control group at 36h. The malondialdehyde (MDA) content indicated the lipid peroxidation stress and the membrane damage degree by the a-linolenic acid treatment. It significantly elevated at 12h, and then decreased gradually until 36h. The photosynthetic oxygen evolution decreased during the period of 8h. The results of this study revealed that the a-linolenic acid could destroy the structure of red tide algal cells by changing the cell membrane permeability and free radical reactions, and in this way the inhibitory effects on the algae were achieved.
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Received: 01 August 2011
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