Effects of microcystins-containing cyanobacteria from a temperate ecosystem on human lymphocytes culture and their potential for adverse human health effects

The present study confirmed the domination of two cyanobacterial genera Microcystis aeruginosa and Aphanizomenon sp. in the summer season in Jeziorsko Reservoir (Central Poland). On the basis of mcyE gene analysis, toxigenic cyanobacterial strains were detected throughout the monitoring period. The highest concentration and toxicity of microcystins (above 2 mu g L-1), with domination of the hydrophobic variant microcystin-YR, appeared in August and reached the cell concentrations for The First Alert Level, according to WHO guidelines for recreational water. For the estimation of the potential threat to human health from regular exposure to microcystins-containing cyanobacteria, in the second phase of study, cultured human lymphocytes were assessed by: XTT reduction test, comet assay and micronucleus test. The effects of three different variants of cyanobacterial extracts including: (i) crude microcystins-containing extracts and (ii) purified microcystins-containing and (iii) nonmicrocystins-containing extracts were investigated. The present study indicated the highest cytotoxicity and genotoxicity of the purified extract containing microcystins (MC-LR, MC-RR and MC-YR). Additionally, no significant effect or clear relation between microcystins concentration in crude extracts and human lymphocytes mortality and DNA damage was observed. The data indicated the influence of other compounds, apart from microcystins, present in the extracts. This research supports the necessity of application of additional tests for determination of total threat from natural cyanobacterial blooms, apart from determination of concentration and toxicity of the main group of cyanotoxins. (C) 2011 Elsevier B.V. All rights reserved.