Microwave oven and boiling waterbath extraction of hepatotoxins from cyanobacterial cells

Low-cost, straightforward methods for the extraction of microcystins and no dularins from cyanobacterial cells were developed using a microwave oven an d boiling waterbath. The use of organic solvents, such as methanol, which c an interfere with sensitive analytical procedures, e.g. immunoassays, can t hus be avoided. Analysis by protein phosphatase inhibition assay and high p erformance liquid chromatography indicated that purified microcystin-LR was unaffected by the microwave oven and boiling waterbath treatments. Four mi crocystins of differing hydrophobicities were successfully extracted from M icrocystis PCC 7813 by both treatments at yields equivalent to those obtain ed by longer protocols using methanol. Assessment of the microwave oven and boiling waterbath extraction methods with laboratory strains and environme ntal samples of cyanobacteria showed good correlation with results from lyo philisation and methanol extraction, when extracts were analysed by high pe rformance liquid chromatography with diode array detection (R(2)greater tha n or equal to 0.92). The microwave and boiling waterbath extraction methods also sterilised the environmental bloom samples, as evidenced by the aboli tion of heterotrophic bacterial growth. (C) 2000 Federation of European Mic robiological Societies. Published by Elsevier Science B.V. All rights reser ved.