Properties of an algicidal bacterium (Flavobacterium sp.) against Karenia mikimotoi isolated from Ise Bay, Japan [Chinese]

摘要

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 Skeletonema 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 K. mikimotoi at an inoculum size of more than 1.1 x 10(2) cfu/ml in the field. [References: 11]