Variation of Toxin Production and Composition in Axenic Cultures of Alexandrium catenella and A. tamarense

Abstract

Eight isolates of the dinoflagellates Alexandrium tamarense and A. catenella germinated from benthic cysts were cultivated in axenic and clonal batch conditions, and changes in PSP toxin content and composition were analyzed by HPLC-fluorometric analysis. Toxin content per cell in two isolates of A. tamarense began to increase gradually from the latter half of the light phase to the middle of the dark phase, and then suddenly decreased. This decrease coincided with cell division. In all isolates of A. tamarense and A. catenella examined through growth phases, toxin composition remained relatively constant at least during exponential growth, while total toxin content increased rapidly in early and mid-exponential growth phase and then decreased drastically as the culture aged. These results and our previous result regarding mendelian inheritance of toxin composition suggest that toxin composition differences have a genetic basis in Alexandrium. © 1993, The Japanese Society of Fisheries Science. All rights reserved.