Detection of potentially producing cylindrospermopsin and microcystin strains in mixed populations of cyanobacteria by simultaneous amplification of cylindrospermopsin and microcystin gene regions.

Cyanobacterial blooms are frequently formed by heterogeneous populations of toxin-producing and non-producing strains. Microcystins (MC) and cylindrospermopsin (CYN) are the most representative cyanobacterial toxins. We have developed a multiplex PCR assay that allows simultaneous detection of MC(+) and/or CYN(+) strains in mixed populations of cyanobacteria. Various primer sets were designed using mcy and aoa gene sequences related with MC and CYN synthesis respectively, to amplify at the same time aoa and mcy sequences. Purified DNA, cultured cell mixtures and field samples with MC and CYN producing strains were used as DNA template. The results show: (i) the expected amplicons were only observed with toxic strains; (ii) cells were suitable as a source of purified DNA for the multiplex PCR; (iii) the assay could detect simultaneously 3 aoa and 3 mcy gene regions with mixed CYN(+) and MC(+) cyanobacteria cells. The method could be applied to environmental samples, allowing in a rapid, economical and easy way to detect simultaneously the presence of CYN(+) and MC(+) cyanobacteria in sestonic fractions of water samples.