Production of C2 toxin by Alexandrium tamarense CI01 using different culture methods

Abstract

The dinoflagellate Alexandrium tamarense CI01 wasgrown in three types of cultures: batch culture, semi-continuous culture andtemporary culture, to investigate the effects of different culture methods oncell growth and the productivity of C2 toxin (C2, a paralytic shellfish toxin).In the batch cultures, cells grew in three phases: a short lag phase, anexponential phase with a specific growth rate (μ) of 0.78day−1 and a relatively long stationary phase. Themaximum toxin productivity was 1.2 μmol L−1 or77 fmol cell−1 in 9 days. In the semi-continuouscultures, cells grewin response to the dilution cycles, with μ values being 0.64, 0.32 and 0.35day−1 for one-day, two-day and three-day cycles,respectively. The toxin yield was about one half of that of the batch cultures.A "temporary" culture method was used to maintain the metabolically activecellsremoved from the semi-continuous cultures, in a nutrient-depleted condition, toachieve a high toxin productivity of 1.0 μmolL−1 in 4 days. Thus,the semi-continuous culture method provided an efficient means to generateamounts of metabolically active algal cells. The temporary culture offered aneffective way to produce C2. The highest yields of C2 were obtained in3–4days when the temporary cultures were aerated.