Early detection of cyanotoxin threat in freshwater bodies by quantitative PCR

Increased frequency of cyanobacterial blooms, caused by rising temperatures and eutrophication, is creating a growing need for reliable methods for early cyanotoxin threat detection in water bodies. Current methods are time-consuming and sensitive to taxonomic inconsistencies. On top of that, they only enable detection of potentially toxin-producing cells when they have already multiplied to a relatively large number. To develop a tool for earlier detection of potentially toxic cyanobacterial strains, we are using qPCR to target genes involved in crucial parts of cyanotoxin synthesis. Detection and quantification of these genes, if incorporated in regular monitoring, might serve as an early warning in case of increased potential for cyanotoxin production. Toxins and genes of interest in this study are microcystins (mcyE), saxitoxins (sxtA) and cylindrospermopsins (cyrJ). The analyses will be carried out on 28 phytoplankton and 23 phytobenthos samples from 15 different freshwater bodies in Slovenia. This way we will include also understudied benthic cyanobacteria and their ability to produce toxic metabolites. Results will be compared with taxa list obtained by traditional microscopic identification methods and with cyanotoxin content evaluated by LC-MS/MS. The study has a potential to prepare the ground for improving current monitoring programs by complementing them with highly sensitive molecular methods. This can provide more in-depth information about dynamics of toxic cyanobacterial populations in water bodies and thus help with adopting appropriate mitigation strategies.