Factors Influencing the Increase in the Proportion of Toxigenic Cyanobacteria of the Microcystis Genus (Chroococcales, Cyanobacteria) in Water Supply Sources

The current data on the factors influencing the toxicity of cyanobacteria of the genus Microcystis and their synthesis of hepatotoxic peptides (microcystins) are summarized. Environmental factors are analyzed and hypotheses are presented explaining their influence on the ratio of toxigenic and nontoxigenic strains in water supply sources and the expression of genes responsible for microcystin synthesis. Particular attention is paid to temperature, illumination, eutrophication, oxidative stress, and the presence of microelements. Information is provided on methods for monitoring toxigenic populations, including molecular biological approaches (PCR, RT-PCR). Research of the environmental factors that promote the growth of toxigenic strains of cyanobacteria of the genus Microcystis may potentially be used to predict the probability of detecting toxins in water supply sources. Based on these studies, it may also be possible to determine optimal sampling intervals for quantitative analysis of microcystins in water supply sources.