<i>Microcystis aeruginos</i> strain [D-Leu1] Mcyst-LR producer, from Buenos Aires province, Argentina

Objective: To show the toxicological and phylogenetic characterization of a native Microcystis aeruginosa (M. aeruginosa) strain (named CAAT 2005-3) isolated from a water body of Buenos Aires province, Argentine. Methods: A M. aeruginosa strain was isolated from the drainage canal of the sewage treatment in the town of Pila, Buenos Aires province, Argentina and acclimated to laboratory conditions. The amplification of cpcBA-IGS Phcocyanin (PC, intergenic spacer and flanking regions) was carried out in order to build a phylogenetic tree. An exactive/orbitrap mass spectrometer equipped with an electrospray ionization source (Thermo Fisher Scientific, Bremen, Germany) was used for the LC/ESI-HRMS microcystins analysis. The number of cell/mL and [D-Leu1 ] Mcyst-LR production obtained as a function of time was modelled using the Gompertz equation. Results: The phylogenetic analysis showed that the sequence clustered with others M. aeruginosa sequences obtained from NCBI. The first Argentinian strain of M. aeruginosa (CAAT 2005-3) growing under culture conditions maintains the typical colonial architecture of M. aeruginosa with profuse mucilage. M. aeruginosa CAAT 2005-3 expresses a toxin variant, that was identified by LC-HRMS/Orbitrapas as [D-Leu1 ] microcystin-LR ([M+H]+=1037.8 m/z). Conclusions: [D-Leu1 ] microcystin-LR has been also detected in M. aeruginosa samples from Canada, Brazil and Argentina. This work provides the basis for technological development and production of analytical standards of toxins present in our region.Facultad de Ciencias ExactasFacultad de Ciencias Naturales y Muse