The degradation of Karenia brevis toxins utilizing ozonated seawater

Florida red tides impose both an economic and health impact on the state. The purpose of this research was to examine the effectiveness of ozone to reduce the numbers of Florida red tide organism (Karenia brevis Davis) and its associated toxins in an artificial seawater environment. The results obtained in this experiment showed an approximate 1.25 log10 unit reduction in the major toxin groups recovered after 10 min of ozone exposure (approximately 135 mg). In initial trials, K. brevis toxins were extracted and reintroduced into an artificial seawater (ASW) media. Subsequent experiments exposed whole cell K. brevis culture to ozone treatment. Samples from both experiments displayed approximately 1.10 log10 unit reduction in total toxin and an approximate 1.25 log10 unit reduction in three of the six major toxins associated with K. brevis (PxTx-1, -2, -9). The reduction in toxin concentration, as measured by high performance liquid chromatography (HPLC) analysis, displayed a positive correlation with the reduction of toxicity as determined by a fish (Cyprinodon variegatus) bioassay. Despite large total doses of ozone applied, as compared to levels that might be found at a commercial ozonation facility, some toxins were still recoverable by HPLC after ozone treatment.