Detection and quantification of toxins in cultures of microcystis aeruginosa (pcc 7820) by hplc and protein phosphatase inhibition assayffect of blending various collectors at bulk

Increasing anthropogenic eutrophication in lakes, drinking water reservoirs and coastal waters is a world-wide phenomenon leading to the formation of blooms of toxic cyanobacteria. These pose a significant threat to human and animal health hence the need for sensitive methods for their detection, identification and quantification. This report presents two methods: analytical high power liquid chromatography coupled with photo-diode array detection and protein phosphatase inhibition assay for the analysis of the most frequently encountered cyanobacterial hepatotoxins – the microcystins. Four microcystin variants: microcystin - LR, - LY, - LW and - LF were identified and quantified by HPLC in cells and growth media of cultured Microcystis aeruginosa PCC 7820. The protein phosphatase inhibition assay was used to estimate potential toxicity of cyanobacterial extracts and both methods showed good correlation (R2 = 0.91). Although HPLC provides accurate and specific information on the identity and quantity of each microcystin variant, it is quite expensive. The assay method on the other hand is relatively cheaper and can be modified to measure milligramme quantities of sample on a benchtop spectrophotometer but individual microcystin variants cannot be identified