A study of toxin production by Gambierdiscus toxicus in culture.

The dinoflagellate Gambierdiscus toxicus was cultivated under different environmental conditions. By an improved toxin extraction procedure the toxicity of methanol extracts was evaluated. Medium composition, temperature decrease, origin (clonal or not clonal) and culture age did not significantly modify toxin production. The discharge of trichocysts and the abundance of bacteria did not affect the toxicity of the dinoflagellate. The toxin yield of G. toxicus cultures was quite stable and a mean of 1100 cells were sufficient to kill one 20 g mouse within 24 hr.