• Korean Journal of Microbiology
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• v.41 no.2
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• pp.112-116
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• 2005

Moderately halophilic bacterium, Kordia algicida gen. nov., sp. novo was isolated from seawater of Masan Bay, Korea, during algal blooming caused by Skeletonema costatum. This bacterium was grown on the ZoBell 2216e medium supplied aged seawater, but not grown the medium supplied $3\%$ NaCl. This bacterium showed absolute requirements for mono and divalent cations such as $Na^+,\;Mg^{2+}\;and\;Ca^{2+}$, since no growth was observed in the medium, which is not supplemented with one of $Na^+,\;Mg^{2+}\;and\;Ca^{2+}$ ions. In kinetic studies for three kinds of cation, Km values of $Na^+,\;Ca^{2+}\;and\;Mg^{2+}$ were determined to 0.202 M, 0.089 mM, and 0.189 mM, respectively. Also, $V_{max}({\mu}max)$ was 0.442 h, 0.411 hand 0.316 h. The bacterial cells were quickly lysed in the condition limited by the cations. This result should be suggested that Kordia algicida originated from marine.

• Journal of Life Science
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• v.15 no.4 s.71
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• pp.578-583
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• 2005

Cell-free culture broth of marine halophilic bacterium, Kordia algicida was shown to possess specific algicidal ability against red tide organism, Cochlodinium polykrikides. Physiochemical characteristics of algicidal material originated in the bacterial culture broth were analyzed that its molecular weight was estimated to a 3,000 dalton and it was stable in heat and pH treatment. The algicidal fraction against C. polykrikoides obtained from gel permeable chromatography contained high concentration of ammonium ion as analyzed by ICP/Mass spectrum. C. polykrikoides by the fraction was quickly lysed within 1 min. It was shown that the effective concentration for algicide against C. polykrikoides was over 1mM of ammonium chloride. On the other hand, other metal ions presented in the algicidal fraction showed no algicidal effect against C. polykrikoides. In additon, ammonium ion exhibited species-specific killing spectrum for two species of red tide organisms, C. polykrikoides and Gymnodinium sanguieum. Therefore, further researches on the killing mechanism against C. polykrikoides exerted by ammonium ion, and subsequent development of replaceable algicidal materials will perform to provide useful tools for the control of red tide.