적조생물 살조세균 탐색 1 . 유해 적조생물 Cochlodinium polykrikoides 살조세균 = Isolation of Marine Bacteria Killing Red Tide Microalgae 1 . Isolation and Algicidal Properties of Micrococcus sp . LG-1 Possessing Killing Activity for Harmful Dinoflagellate , Cochlodinium polykrikoides

다국어 초록 (Multilingual Abstract)

In this study, we have investigated the distributions and killing effects of marine bacteria that tend to kill the red tide microalgae, C. polylaikoides in the area of Masan bay from June to October, 1996. To summarize, C. polykrikoides killing bacteria were detected at 10² to 10³ cells/㎖ of seawater samples during the survey period, and the bloom was observed in September by containing 4.8×10` cells/㎖. It appears, however, that the number of these bacteria is decreased (2.0× 10² cells/㎖) in October. A total of 110 strains were isolated from seawater samples and seawater filtrate (pore size, 0.8 ㎛)-containing mixed culture of C. polykrikoides in which the mixed culture was grown in f/2 medium. As results, we have successfully isolated Micrococcus sp. LG-1 which shows a remarkable killing effect against the C. polykrikaides. The cell numbers of C. polykrikoides were decreased to less than 10 cells/㎖ within 6days and 5days after inoculation of Micrococcus sp. LG-1 into the lag and logarithmic growth phases of C. polykrikoides, respectively. Therefore, it appears that inoculation of Micrococcus sp. LG-1 against the logarithmic C. polykrikoides is more effective than the lag growth phase. In addition, the killing effects were increased in accordance with bacterial cell densities inoculated in a dose dependent manner. Especially, the filtrate of killing bacterium culture (pore size, 0.2㎛) revealed a dramatic effect in which C. polykrikoides were decreased to less than 10 cells/㎖ of culture within 1 hr, 1.5 hrs, 1.5 hrs, 3.5 hrs. and 5.5 hrs after inoculations of the culture filtrate with concentration of 30%, 20%, 10%, 5% and 2.5%, respectively. Moreover, Micrococcus sp. LG-1 showed a selective specificity against C. polykrikoides and any other killing effects of Micrococcus sp. LG-1 were not observed against Alexandrium tamarense, Prorocentrum micans, Scrippsiella trochoidea. and Gymnodinium sanguineum.