Stimulation and inhibition effects of algae-lytic products from Bacillus cereus strain L7 on Anabaena flos-aquae

摘要

Alga-bacterium relationships between a Bacillus cereus strain L7 and Anabaena flos-aquae were studied based on the effects of the algicidal substances on algal growth indicators such as enzyme activity and membrane lipid peroxidation. When exposed to algae-lytic products at a concentration of 0.05 mg mL-1, chlorophyll a (Chla), protein and phycobiliprotein contents increased significantly (p<0.05); superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activities and malondialdehyde (MDA) concentrations increased slightly to stimulate the algae growth. When exposed to algae-lytic products at a concentration of 0.5 mg mL-1, algae growth and composition were inhibited. Chla, protein and phycobiliprotein concentrations decreased significantly (p<0.05 for protein, p<0.01 for Chla and phycobiliprotein). MDA concentrations increased significantly (p<0.05). POD and CAT activities increased by approximately six and three times, respectively, in 24 h compared with the control, then decreased to the initial level in 4 days. Algae-lytic products have not only inhibition but also stimulation effects on A. flos-aquae. Such effects are associated with antioxidative/oxidative reactions as indicated by the biomarkers SOD, POD, CAT, and MDA.