Nutritional supplementation to increase growth and paralytic shellfish toxin productivity by the marine dinoflagellate Alexandrium tamarense

The effects of supplementation with bicarbonate and K-nutrients on the growth and C2 toxin (C2T) productivity by a model dinoflagellate, Alexandrium tamarense ATCI01, were investigated in batch cultures. Supplementation with bicarbonate at a level of 5 mM increased both the cell density and toxin yield to 140 and 210\%, respectively, compared with the non-supplemented control culture, and achieving 13.6 x 10(3) cells/ml and 875 mug toxin/l. Supplementation at the start or at day 6 of the cultures produced similar effects. The results confirm that carbon can be limiting in cultures of this photosynthetic dinoflagellate, where dense growth was intentionally maintained for high toxin yield. When the cultures were supplemented both with bicarbonate at 5 mM and K-nutrients to double the nitrate and phosphate supply, the cell density and toxin yield further increased to 29.8 x 10(3) cells/ml and 1080 mug toxin/l, respectively, regardless of whether the supplementation of the cultures was made at the start or at day 6. The results indicate that supplementation with bicarbonate and K-nutrients would increase the yield of C2T in mass production operations using this model dinoflagellate strain. (C) 2002 Elsevier Science B.V. All rights reserved