Toxic cyanobacteria strains in lowland dam reservoir [Sulejow Res., Central Poland]: amplification of mcy genes for detection and identification

Excessive eutrophication causes the growth of microcystin-producing Cyanobacteria and leads to an increased human health risk. This paper reports the analyses of Cyanobacteria toxigenicity (the degree of potential toxicity) in lowland dam reservoir (Sulejów Reservoir, Central Poland) by the use of PCR-based methods. The reservoir (area 22 km², mean depth 3.3 m) is very eutrophic water body permanently blooming with blue-green algae (mainly Microcystis aeruginosa). For identification of cyanobacterial genus the 16S rRNA region was used. Cyanobacterial genus was detected during the whole monitoring period in summer 2003. The potential toxicity of cyanobacteria was determined by amplification of selected mcyA,B,E genes in the microcystin biosynthesis pathway. All of the analyzed genes were detected at the beginning of the growing season during low cyanobacterial biomass (0.67 mg l⁻¹). 89% of the samples were found to be positive for mcyA detection. Early detection of mcy genes at the beginning of summer preceded a period of the highest microcystins concentration (2.91 µg l⁻¹ in maximum) and toxicity established by ELISA (enzyme-linked immunosorbent assay – enables determination of microcystins concentration) and PPIA (protein phosphatase inhibition assay – enables estimation of microcystins toxicity). We show that toxigenic (potentially toxic) strains of cyanobacteria occurred in Sulejów Reservoir throughout the summer and genetic markers were effective in early identification of microcystin-producing genera. Application of molecular methods in parallel with toxicity testes can provide complete information to prevent any human health risk.