Legrand, C. Dept. of Marine Sciences, University of Kalmar, catherine.legrand@ng.hik.se
Johnsen, G. Norwegian University of Science and Technology, geir.johnsen@vm.ntnu.no
Hummert, C. Inst. of Nutrition and Environment, University of Jena, b5huch@rz.uni-jena.de
GranÚli, E. Dept. of Marine Sciences, University of Kalmar, edna.graneli@ng.hik.se

 
VARIATION IN TOXIN PRODUCTION IN TWO STRAINS OF ALEXANDRIUM TAMARENSE: EFFECTS OF NITROGEN AND PHOSPHORUS REPLETE VS. LIMITED GROWTH CONDITIONS
 
The effect of nitrate-N and phosphate-P ratios (N:P = 1.6-160 by atoms) on PSP toxin content and cellular chemical composition in the dinoflagellate Alexandrium tamarense were examined in non bacteria free semi-continuous cultures. Results were compared between two strains (KAC01, KAC02) of A. tamarense isolated from the same drop of water, for which toxin profiles and abundance of associated bacteria were different. For the two isolates, cellular toxin contents were higher in replete and P-limited cultures compared to N-limited cultures. Toxin content (fmol cell-1) remained at constant levels within the experiment (steady-state phase) for all treatments.The presence of N-sulfocarbamoyltoxins (i.e. Bx, Cx) was only detected in KAC02. In all treatments, except for P-limited cultures, toxin content values (fmol cell-1 ) were comparable between the two strains. KAC02 P-limited cells exhibited higher toxin content. Nitrogen resupply induced an elevation of the toxin content in previously N-limited cells comparable to the highest toxin content observed in P-limited cultures. The fraction of cell-N bound in the form of PSP toxins was larger in P-limited cells than in nutrient replete cells, and varied in inverse proportion with cell-N bound to chlorophyll a on a per cell basis.
 
Day: Friday, Feb. 5
Time: 12:15 - 12:30pm
Location: Eldorado Hotel
 
Code: SS42FR1215E