Isolation of algicidal bacteria chemotaxiing toward blooming microalgae and its application as a "missile" for the prevention of red tide

从微生物学角度出发，对赤潮的微生物防治进行了初步的研究，目的是分离出能杀灭微藻的抑藻菌群，或对某些特殊藻类趋化的抑藻菌群。在2年的研究中，新分离出88株杀藻菌，其中23株仅能杀灭有害的赤潮浮游植物——mikimotoi裸子藻。我们还分离到了12株可移动的杀藻菌株，其中6株对两种赤潮浮游植物均表现出趋化特性。一株仅被古查托纳菌吸引的菌株与一种藻类混合时，对米基motoi和古查托纳菌均有杀灭能力。然而，当该细菌接种到两种藻类的混合培养物中时，它首先抑制了C. antiqua的生长，对G. mikimotoi的抑制作用延迟。这些结果表明，细菌对微藻的物种特异性抑制在一定程度上可以用杀藻细菌的趋化特性来解释，这类细菌可以作为“导弹”来预防赤潮。

We tried to isolate algicidal bacteria killing some restricted taxonomical groups of blooming microalgae, or those chemotaxiing toward some special algal species, for the microbiological prevention of red tides. During the study for 2 years, 88 strains of algicidal bacteria were newly isolated, and 23 strains out of 88 killed only Gymnodinium mikimotoi, a noxious red tide phytoplankton. We also isolated 12 motile algicidal strains, and among those, 6 bacteria showed chemotactic properties toward either of red tide phytoplankton species. One strain attracted only by Chattonella antiqua showed killing ability against both G. mikimotoi and C. antiqua when it was mixed with one algal species. However, when this bacterium was inoculated into mixed cultures of the two alagal species, it suppressed the growth of C. antiqua at first and inhibition against G. mikimotoi was delayed. These results suggest that a part of species-specific suppression against microalgae by bacteria would be able to be explained by chemotactic properties of algicidal bacteria, and that such bacteria could be useful for preventing red tide by applying them as a "missile".