Deciphering the diversity and concentrations of cyanopeptides from blooms in Ontario and Quebec, Canada

E. McCann, D. McMullin* Cyanobacteria blooms release mixtures of biologically active compounds into freshwater systems. These poorly studied compounds pose undetermined risks to both human and ecosystem health, and negatively impact local economies that depend on freshwater resources. While microcystins are extensively studied, little is known about the chemistry, structural diversity, toxicology and environmental concentrations of less studied cyanopeptide groups such as, anabaenopeptins, cyanobactins, cyanopeptolins, microginins and aeruginosins. The application of mass spectrometry and metabolomic data processing techniques are powerful tools for deciphering the mixtures of compounds released by cyanobacteria. A Non-targeted high resolution tandem mass spectrometry-based metabolomics approach was used to detect more than one-hundred unique cyanopeptides from fifty-five bloom samples collected from fifteen watercourses near the city of Ottawa in Canada. Microcystins and select other cyanopeptides were quantified with reference materials. The concentrations of other cyanopeptide groups for example, anabaenopeptins cyanopeptolins and microginins, were determined semi-quantitatively. Sixty of the compounds detected contributed significantly to the variation in cyanopeptide profiles between watercourses. The most commonly detected cyanopeptide groups were anabaenopeptins (thirty-three congeners) and cyanopeptolins (thirty-two congeners). Microcystins were detected in forty-one of the fifty-five bloom samples, where microcystin-LR was detected most often; however, microcystin-LA amounts were consistently the highest when detected for this toxin group