Effects of water temperature on paralytic shellfish poisoning toxin content and toxin composition of Alexandrium catenella (toxic dinoflagellate) under nitrogen- or phosphorus-limited conditions
2007
Matsuda, A.(Kochi Univ., Nankoku (Japan). Faculty of Agriculture) | Nishijima, T. | Fukami, K. | Adachi, M.
The purpose of this study is to unveil the variation in paralytic shellfish poisoning (=PSP) toxin content and toxin composition in Alexandrium catenella under nitrogen- or phosphorus-limited conditions at various temperatures. An axenic clone of A. catenella (strain TNY7) has been grown in nitrogen- or phosphorus-limited semi-continuous culture at 10, 15 and 20 deg C. The dilution rate was set to 0.055/d. PSP toxin content and composition of the cells collected just before cell divisions were analyzed using an HPLC-fluorometric analyzer. The cellular toxin content under nitrogen-limited condition at 15 deg C (5.0 fmol/cell) was similar to that at 20 deg C (3.8 fmol/cell). The cellular toxin content under nitrogen limited condition at 10 deg C (19.1 fmol/cell) was higher than that at 15 and 20 deg C. The cellular toxin content under phosphorus- limited condition at 15 deg C (61.0 fmol/cell) was almost the same as that at 20 deg C (64.1 fmol/cell). Under phosphorus-limited condition at 10 deg C, cellular toxin content of 104.2 fmol/cell, which is the highest content ever found during our studies, was obtained. Toxin composition and ratio remained constant independent of nitrogen or phosphorus limitation and water temperature. This study shows that water temperature (15-20 deg C) does not have a significant effect on cellular toxin content and low water temperature (10 deg C) increases cellular toxin content under nutrient-limited conditions.
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