Production of ciguatoxin and maitotoxin by strains of Gambierdiscus australes, G. pacificus and G. polynesiensis (Dinophyceae) isolated from Rarotonga, Cook Islands

The isolation and culturing of toxic Gambierdiscus species is desirable for obtaining reliable sources of toxins responsible for Ciguatera Fish Poisoning (CFP) in order to provide reference materials and purified standards for chemical analyses and bioassays. Gambierdiscus polynesiensis CAWD212, G. pacificus CAWD213 and G. australes CAWD149 and 216 have been isolated from samples of sea water from the Cook Islands. G. polynesiensis produced ciguatoxins (CTX; 18.2 pg per cell) and G. australes CAWD149 produced maitotoxin (MTX; 8.3 pg per cell) and in both extracts putative MTX-3 was detected. G. pacificus also produced putative MTX-3. The toxicities of extracts of G. polynesiensis and G. pacificus were similar by i.p. injection (LD50s of 1.0 mg/kg and 0.8 mg/kg respectively), but when administered by gavage, the MTX-3 analogue producing G. pacificus (LD50 251 mg/kg) was 30-times less toxic than the CTX-producing G. polynesiensis (LD50 7.9 mg/kg). Consumption of fish contaminated by CFP has caused illness and even death in the Cook Islands and throughout the Pacific region and is now considered a globally neglected disease. Large-scale cultures of these organisms are now available, and isolation of the toxins they produce is in progress.