A UNIFIED BIOSCREEN FOR THE DETECTION OF DIARRHETIC SHELLFISH TOXINS AND MICROCYSTINS IN MARINE AND FRESH-WATER ENVIRONMENTS

Capillary electrophoresis (CE) coupled with liquid chromatography (LC)-linked protein phosphatase (PPase) bioassay was used to detect sensitively both diarrhetic shellfish toxins and hepatotoxic microcystins in marine and freshwater samples. This procedure provided a quantitative bioscreen for the rapid optical resolution of either of these toxin families in complex mixtures such as cultured marine phytoplankton, contaminated shellfish and cyanobacteria (natural assemblages). Following detection, identified toxins were purified by an enzyme bioassay-guided two-step LC protocol. Using the latter approach, at least four microcystins were rapidly isolated from a cyanobacteria bloom (largely Microcystis aeruginosa) collected from a Canadian drinking-water lake, including a novel microcystin termed microcystin-XR, where X is a previously unidentified hydrophobic amino acid of peptide residue molecular mass 193 Da. The unified CE/LC-linked PPase bioscreen described provides a powerful capability to dissect multiple toxin profiles in marine or freshwater samples contaminated with either okadaic acid or microcystin classes of toxin.