RESUMO
The algal growth and physiological characters of Aphanizomenon flos-aquae were studied under the stress of Sagittaria sagittifolia extract. The results showed that the growth of A. flos-aquae was significantly inhibited by S. sagittifolia extract. The exopolysaccharide (EPS), total soluble protein, intracellular phosphorus (o-PO4-P) contents and malondialdehyde (MDA) contents in A. flos-aquae cells increased significantly. These results suggested that A. flos-aquae can adapt to stress by increasing its normal metabolic activity. The algal cellular antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD), were triggered to different degrees when exposed to S. sagittifolia extract. The MDA contents and activities of SOD, CAT and POD in algal cells suggested that oxidative damage induced by S. sagittifolia extract via the oxidation of ROS (O2·-) might be an important factor responsible for the inhibition of the growth of A. flos-aquae. In addition, SOD may be an important site for the inhibition of S. sagittifolia extract on A. flos-aquae cells. These results indicate that S. sagittifolia may be a good candidate for controlling A. flos-aquae blooms.