RESUMEN
Cyanobacteria are prokaryotic and photosynthetic organisms, which can produce a wide range of bioactive compounds with different properties; including a variety of toxic compounds, also known as cyanotoxins. In this work, we describe the isolation of seven cyanobacterial strains from two reservoirs in São Paulo State, Brazil. Seven different chemical variants of microcystins (MC-RR, MC-LR, MC-YR, MC-LF, MC-LW, and two demethylated variants, dm-MC-RR and dm-MC-LR) were detected in three of the ten isolated strains. One particular Microcystis aeruginosa strain (LTPNA 02) was chosen to evaluate its growth by cell count, and its toxin production under seven different nutritional regimes. We observed different growth behaviors in the logarithmic growth period for only three experiments (p < 0.05). The total growth analysis identified four experiments as different from the control (p < 0.01). Three microcystin variants (MC-RR, MC-LR and MC-YR) were quantified by liquid chromatography-tandem mass spectrometry. At the experimental end, the toxin content was unchanged when comparing cell growth in ASM-1 (N:P = 1), MLA and BG-11 (N:P = 10) medium. In all other experiments, the lowest microcystin production was observed from cells grown in Bold 3N medium during the exponential growth phase. The highest microcystin content was observed in cultures using BG-11(N:P = 100) medium.
RESUMEN
A N'dena; dans la Vallee de la Bini (Ademaoua) ou la prevalence de l'onchocercose est de 51;4 pour cent d'apres la microfilarodermie; l'importance des atteintes cutanees et oculaires est mesuree. La depigmentation et l'atrophie cutanees s'observent chez 33;1 pour cent des habitants. Et 20;3 pour cent d'entre eux sont porteurs de kystes onchocerquiens. Des microfilaires sont vues dans le segment anterieur de l'oeil chez 23;3 pour cent des sujets et dans la chambre posterieure chez 9;8 pour cent. L'etude du pouvoir pathogene de la souche forestiere locale d'o. volvulus isolee met en evidence un contraste entre; d'une part; une infestation onchocerquienne massive et; d'autre part; la faible repercussion de cette pathologie sur la sante des populations