Domoic acid-binding substance found in bacteria isolated from causative diatom of domoic acid

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研究成果の概要（英文）：Domoic acid (DA) is a compound with anthelmintic activity which was identified for the first time in a red algae Chondria armata. On the other hand, DA was found to be the causative toxin for Amnesic Shellfish Poisoning (ASP) that was first recognized in Canada in 1978. Accumulation of DA in shellfish was observed during the bloom of Pseudo-nitzschia multiseries, Thus this species was considered to be the causative species. Soon it was confirmed by culture experiment. Now several species of Pseudo-nitzschia are considered to be the causative species. The species identification of Pseudo-nitzschia spp. is usually performed by electron microscope. Thus it is impossible to know relation between DA accumulation and bloom of toxic Pseudo-nitzschia species. We developed an ELSA for DA and tried to survey the relation between the DA level in plankton samples and that accumulated in the shellfish. Interestingly, the DA level of shellfish did not increase during when significant level of DA was observed in plankton samples. In contrast, DA of shellfish increased much around 1 week after DA in plankton samples disappeared. These facts strongly suggest the occurrence of DA-binding substance in plankton cells. -DA may be released when the DA-binding substance was digested by the shellfish. In the present study, we could show the possible occurrence of the DA-binding substance in bivalve that accumulates high level of DA.