Algicidal Effect of Serratia sp. PDGS120915 against Harmful Dinophyceae Algae

Harmful algal blooms (HABs) can cause massive economic losses. In this study, the bacterial strain PDGS120915 produced a red pigment (prodigiosin). It was isolated from lightly contaminated stream water taken from Busan, Korea. The isolated strain was identified as Serratia sp. by 16S rDNA sequence analysis and morphological characteristics. Prodigiosin from Serratia sp. PDGS120915 was extracted and purified by high-performance liquid chromatography (HPLC). This pigment showed algicidal activity against dinophyceae, Alexandrium catenella, Gymnodinium impudicum, and Cochlodinium polykrikoides. The algicidal activity of this prodigiosin against dominant bloom-forming dinophyceae on the Korean coast was examined, and it exhibited high algicidal activity against A. catenella (83.4%), G. impudicum (92.1%), and C. polykrikoides (92.3%). Furthermore, prodigiosin from Serratia sp. PDGS120915 showed a broad range of algicidal activity against raphidophyceae (Chattonella marina, Heterosigma akashiwo), coscinodiscophyceae (Skeletonema costatum), and bacillariophyceae (Nitzschia pungens). The optimum concentration of this activity was observed at 5 ppb. Additionally, algicidal activity increased rapidly after 9-h and showed more than 80% algicidal activity at 12-h. Our research suggested that the algicidal bacterium Serratia sp. PDGS120915 and its algicidal compound, prodigiosin, could be a potential bio-agent for the prevention and control of harmful algal blooms.