Journal of Microbiology

Research Support, Non-U.S. Gov't

Isolation and Characterization of a Marine Algicidal Bacterium against the Harmful Raphidophyceae Chattonella marina: Yun Sook Kim , Dae-Sung Lee , Seong-Yun Jeong , Won Jae Lee , Myung-Suk Lee; J. Microbiol. 2009;47(1):9-18. Published online February 20, 2009; DOI: https://doi.org/10.1007/s12275-008-0141-z

Abstract: A bacterial strain named AB-4 showing algicidal activity against Chattonella marina was isolated from coastal water of Uljin, Republic of Korea. The isolated strain was identified as Bacillus sp. by culture morphology, biochemical reactions, and homology research based on 16S rDNA. The bacterial culture led to the lysis of algal cells, suggesting that the isolated strain produced a latent algal-lytic compound. Amongst changes in algicidal activity by different culture filtrate volumes, the 10% (100 ?/ml) concentration showed the biggest change in algicidal activity; there, estimated algicidal activity was 95%. The swimming movements of Chattonella marina cells were inhibited because of treatment of the bacterial culture; subsequently, Chattonella marina cells became swollen and rounded. With longer exposure time, algal cells were disrupted and cellular components lost their integrity and decomposed. The released algicide(s) were heat-tolerant and stable in pH variations, except pH 3, 4, and 5. Culture filtrate of Bacillus sp. AB-4 was toxic against harmful algae bloom (HAB) species and nontoxic against livefood organisms. Bacillus sp. AB-4 showed comparatively strong activity against Akashiwo sanguinea, Fibriocapsa japonica, Heterosigma akashiwo, and Scrippsiella trochoidea. These results suggest that the algicidal activity of Bacillus sp. AB-4 is potentially useful for controlling outbreaks of Chattonella marina.

Journal Article

Monitoring of Algicidal Bacterium, Alteromonas sp. Strain A14 in its Application to Natural Cochlodinium polykrikoides Blooming Seawater Using Fluorescence In Situ Hybridization: Bo-Kyung Lee , Toshiya Katano , Shin-Ichi Kitamura , Myung-Joo Oh , Myung-Soo Han; J. Microbiol. 2008;46(3):274-282. Published online July 5, 2008; DOI: https://doi.org/10.1007/s12275-007-0238-9

Abstract: The red tide of dinoflagellate, Cochlodinium polykrikoides has frequently occurred in coastal waters, causing severe damage to fisheries. In the present study, the algicidal bacterium Alteromonas sp. A14 isolated from the southern coast of Korea was applied to a red tide of C. polykrikoides in a laboratory experiment. In the experiment, the abundance of the strain A14 was monitored using fluorescence in situ hybridization. Inoculation of the A14 at a final cell density of 9.0×105 cells/ml caused a significant decrease in C. polykrikoides abundance from 1,830 to 700 cells/ml during 2 days, while abundances of harmless diatoms rapidly increased from 3 days. Abundances of both A14 and other bacteria increased to 1 day. After 1 day, with flagellate abundance increased, bacterial abundance decreased. Finally, algicidal bacterial abundance decreased to 3.5×104 cells/ml. In the biological control of harmful algal blooms, in addition to decrease in target algal abundance and not occurrence of other harmful blooms, decrease in abundance of utilized organism is also important. This study emphasizes the importance of monitoring the inoculated bacterium when applying bacterium to natural seawater.

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