Properties of an algicidal bacterium (Flavobacterium sp.) against Karenia mikimotoi isolated from Ise Bay, Japan
2004
Iwata, Y. (Mie Univ., Tsu (Japan). Faculty of Bioresources) | Sugahara, I. | Kimura, T. | Kowa, H. | Matsumoto, A. | Noritake, K.
A bacterial strain MA10 which showed algicidal activity against Karenia (=Gymnodinium) mikimotoi was isolated from Ise Bay, Mie pref., Japan. The bacterial strain MA10 was identified as Flavobacterium sp. Strain MA10 had algicidal activity against K. mikimotoi, but did not inhibit the growth of Chattonella antiqua, Chattonella marina, Heterosigma akashiwo or Skektonema costatum. When strain MA10 was inoculated into an axenic culture of K. mikimotoi at the initial bacterial number of 4.5 x 10**1 cfu/ml, the bacteria increased rapidly and reached 6.2 x 10**6 cfu/ml after incubation for 3 days. Simultaneously, the density of K. mikimotoi decreased and no K. mikimotoi cells were observed after 6 days. On the other hand, strain MA10 could not inhibit the growth of K. mikimotoi when the bacteria were inoculated into K. mikimotoi in the presence of the natural bacterial community at the initial bacterial number of 1.1 x 10**1 cfu/ml, but the algicidal effect was shown when the initial bacterial number was more than 1.1 x 10**2 cfu/ml. These results suggested that strain MA10 has algicidal activity against if. mikimotoi at an inoculum size of more than 1.1 x 10**2 cfu/ml in the field.
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