Screening of Algicidal Bacteria and Development of Bio-Eco Ceramic System for Controlling Harmful Algal Blooms (Cochlodinium polykrikoides) in Fish-Raising Farm

Abstract

Harmful algal blooms (HABs) have made massive economic losses and marine environmentaldisturbances. Normally, loess was scattered to control HABs in Korea, but it arises secondary contamination problems. Therefore, development of highly effective and eco-friendly strategies are required to control the HABs. In the present study about 300 bacterial strains were screened which kills the Cochlodinium polykrikoides, a major kind of HABs in Korea. From the screening result, strain 2R1 was selected for further study which showed 98.9% algicidal activity against C. polykrikoides at their optimal growth conditions (modified marine broth with 1% NaCl at 28℃). Moreover, selective algicidal activity of strain 2R1 was also tested against few more HABs in Korea such as Chatonella marina, Heterocapsa triquetra, Heterosigma akashiwo, Scrippsiella trochoidea, Skeletonema costatum and Prorocentrum minimum. Strain 2R1 did not showed any activity against these algal blooms. To supply and preserve strain 2R1 continuously, an algicidalreactor with bio-eco ceramics was developed consisting of the strain and multi-pore ceramics. This system resulted in more than 94.0% of algicidal activity when the bacteria grown on their optimal conditions. From this study, it was determined that the strain 2R1 have selective algicidal activity against C. polykrikoides and the strain had no efficiency about other six kinds of HABs. The eeffective and eco-friendly strategiesare required to control the HABs. In the present study about 300 bacterial strains were screened which kills the Cochlodinium polykrikoides, a major kind of HABs in Korea. From the screening result, strain 2R1 was selected for further study which showed 98.9% algicidal activity against C. polykrikoides at their optimal growth conditions (modified marine broth with 1% NaCl at 28℃). Moreover, selective algicidal activity of strain 2R1 was also tested against few more HABs in Korea such as Chatonella marina, Heterocapsa triquetra, Heterosigma akashiwo, Scrippsiella trochoidea, Skeletonema costatum and Prorocentrum minimum. Strain 2R1 did not showed any activity against these algal blooms. To supply and preserve strain 2R1 continuously, an algicidal reactor with bio-eco ceramics was developed consisting of the strain and multi-pore ceramics. This system resulted in more than 94.0% of algicidal activity when the bacteria grown on theiroptimal conditions. From this study, it was determined that the strain 2R1 have selectivealgicidal activity against C. polykrikoides and the strain had no efficiency about other six kinds of HABs. The extracted algicidal activity materials were further analyzed by GC-MSD which indicated them as 7-Methyl-8-hydroxyquinoline and 1-Methyl-β-carboline. In conclusion, the present research have devised an innovative bioreactor system which have very high potential to control HABs. In addition, two promising algicidal compounds are also identified having HABs removal activity.