Algicidal characteristics of Pseudomonas 2-4:based on ecological risk assessment

Abstract:

[Objective]To explore the inhibitory effects of Pseudomonas 2-4 and its product on algae based on ecological risk assessment.[Methods]Algicidal bacterial strain 2-4(Pseudomonas sp.) was isolated,and the suppression of strain 2-4 and its product on algae was examined based on orthogonal test and kinetic stimulation.Acute toxicity test was conducted to evaluate the ecological risks.[Results] Under the optimal conditions,strain 2-4(V/V=15%) removed 92.81% of the Microcystis aeruginosa in 4 days,and the algal inhibition could be characterized by the first-order kinetic model (t_1/2=126 h).Strain 2-4 had a broad-spectrum inhibitory activity and the inhibitory effects of Pseudomonas sp.on Ulothrix sp.,Chlorella pyrenoidosa,and Tetradesmus obliquus were reported for the first time.The product (<500 Da) from strain 2-4 had inhibitory effects on algae,but could be destroyed by high temperature and strong acid and alkali.The results of acute toxicity test showed the bacterial liquid at>1.5%(V/V) was toxic to Daphnia magna and the product at>2%(V/V) was toxic to D.magna and Gobiocypris rarus but nontoxic to Photobacterium phosphoreum.At the safe concentration,strain 2-4(V/V=1.5%) and its product (V/V=10%) decreased chlorophyll a in the lake with algae bloom by 4.83%–42.94% and 30.62%–68.69%,respectively.[Conclusion] We analyzed the algicidal effect of strain 2-4 and its product in the safe concentration and clarified the relationship between the ecological toxicity and the inhibitory effects of strain 2-4,hoping to provide a reference for biocontrol of algae.