Cianotoxinas em ostras e em águas de cultivo da costa norte do Brasil

Abstract

Cyanobacteria are photosynthetic prokaryotic organisms and under conditions favorable to their growth can form blooms. They are also capable of producing cyanotoxins, secondary metabolites that have a toxic effect on eukaryotic organisms including man. As part of phytoplankton the cyanobacteria participate in the food chains, thus the ingestion of shellfish, that have been continuously fed toxic cyanobacteria and accumulated the toxins in their tissues generates the possibility of transfer to the man through their consumption bringing serious risks to their health. There is still very little research on the contamination (by cyanotoxins) of shellfish intended for human consumption. Therefore, this study was to verify the occurrence of cyanotoxins in culture waters and in the tissue of oysters destined for human consumption. The water and oyster samples were collected from two municipalities located in the northeast of Pará. The cyanotoxins research was performed using High Performance Liquid Chromatography (HPLC). The cyanobacteria present in the water, isolated and cultured from oyster shells were identified. No microcystins and saxitoxins were detected in water samples and oyster extracts from both growing sites. However, three genera of cyanobacteria - Aphanizomenon, Oscillatoria and Phormidium were identified in Curuçá and three genera of cyanobacteria in São Caetano de Odivelas - Aphanothece, Oscillatoria and Phormidium, all known to contain toxic species. The presence of saxitoxins in extracts from cyanobacterial cultures was detected from the oyster shells of both growing sites, indicating the presence of toxic species despite the absence of bloom. In this study, it was verified that the cultivation of oyster sites are suitable for consumption, free of contamination by microcystins and saxitoxins, however, it is necessary to implement specific legislation and the monitoring of these crops in order to ensure consumer health.