Optimization of Algicidal Activity for Alteromonas sp. FDHY-03 against Harmful Dinoflagellate Prorocentrum donghaiense

Abstract

Prorocentrum donghaiense is a harmful-algal-bloom-forming species of planktonic dinoflagellates widely distributed around the world, which threatens the marine environment and human health. Bacteria are promising biological agents to control algal growth in HABs. Previously, we isolated an Alteromonas sp. FDHY-03, a P. donghaiense-lysing bacteria strain, from Xiapu Sea area of China. In order to improve the algicidal activity of this strain, we optimized the medium composition and culture conditions. Based on single-factor method experiment design, the optimum medium component of algicidal effect for strain FDHY-03 was sucrose and peptone. The result of Plackett–Burman design indicated that three significant factors (sucrose, peptone, and rotational speed) appeared. Finally, the concentrations of key factors were confirmed by central composite design (CCD) and response surface methodology (RSM). Under the optimized medium, the algicidal rate of strain FDHY-03 against P. donghaiense improved by 67.15%, and the OD600 value increased by 2.86-fold. The optimal source and condition were sucrose 0.46% (w/v), peptone 4.25% (w/v) addition, and rotation speed 255 rpm. Overall, this study provides an optimized method and optimum medium for improving the algicidal activity against P. donghaiense, and has a positive influence on algae-lysing bacteria for controlling the blooms of the algae in the environment.