1ST REPORT OF MICROCYSTINS FROM A BRAZILIAN ISOLATE OF THE CYANOBACTERIUM MICROCYSTIS-AERUGINOSA

This is the first report on microcystins, cyclic heptapeptide hepatotoxins, from Brazilian water supplies. A colony isolate (NPJB-1) of the colonial cyanobacterium Microcystis aeruginosa from Lagoa das Garcas, Sao Paulo, was cultured under non-axenic conditions. Exponential phase cells were harvested, concentrated and lyophilized for mouse bioassays and toxin extraction. The LD100 of lyophilized cell suspensions was approximately 31 mg kg-1 (dry cell weight/animal weight). Isolation, purification and characterization of the toxins were carried out by reversed phase HPLC, HPLC amino acid analysis and fast atom bombardment mass spectrometry. Strain NPJB-1 produces two different hepatotoxic heptapeptide microcystins. The main one was microcystin-LR, the most commonly reported microcystin from cyanobacteria. The other was microcystin-LF, the phenylalanine variant of microcystin-LR. This is the first published report for microcystin-LF.