Warm Seawater Microalgae: Growth and Toxic Profile of Ostreopsis Spp. from European Coasts

Abstract

Palytoxin (PLTX) is a complex marine toxin synthesized by the soft coral Palythoa toxica and by species of the benthic dinoflagellate Ostreopsis spp. The toxin binds to the active Na, K-ATPase pump in the cellular membrane. This interaction changes the protein conformation and produces a non-specific cation channel. Using the Fluorescent Polarization (FP) technique to quantify the PLTX concentration, the production of PLTX-like products was measured in several cultures of Ostreopsis ovata and Ostreosis siamensis. The cultures were grown under different conditions to study the optimal parameters to grow and to produce toxins. Serious difficulties were found to quantify the number of cells at the end of the exponential phase. In order to avoid any toxin loss, the weight of the pellet obtained after careful filtration was used as reliable parameter to calculate the growth of the cultures. Also, this parameter was used to refer the results of toxin concentration. In addition the toxicity of the cultures was measured by mouse bioassay. In these conditions, the optimal parameters to grow these strains are 24°C, 37‰ of salinity and 16:8 h light-dark photoperiod. Within these parameters high amounts of PLTX-like compounds with different toxin profiles were obtained.