LAUSR

Using Microcystis aeruginosa as a research receptor, the inhibitory effects of 0.3-1.1 g/L root, stem and leaf extracts from Alternanthera philoxeroides on algae growth and their underlying mechanisms were studied. The biomass, oxygen radical (O2), malondialdehyde (MDA), nucleic acid, microcystin and polysaccharide contents were determined and cell morphological and structural variations were observed. Results showed that the extracts from A. philoxeroides significantly inhibited the growth of M. aeruginosa in a concentration-dependent manner. In particular, root extract had the strongest inhibition effect, followed by stem and leaf extract. The growth of more than 80% of all M. aeruginosa was inhibited after 96 h exposure to 1.1 g/L root extract. Besides, the damage degree of cells treated with root extract after 72 h was shown by the scanning electron microscope. With the accumulation of O2, the contents of all physiological indicators increased with higher extract concentrations, except for MDA content, which decreased first after 24 h culture at 0.3 g/L treatment. In conclusion, A. philoxeroides had a certain ecological control capacity on M. aeruginosa growth by aggravating oxidative stress, destroying membrane permeability, changing cell structure and finally inducing plasmatorrhexis, but the specific action of allelochemicals it contained remained to be further explored.