INBIOTEC   24408
INSTITUTO DE INVESTIGACIONES EN BIODIVERSIDAD Y BIOTECNOLOGIA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Morphologic and molecular characterization of two native toxigenic bloom-forming cyanobacteria
Autor/es:
AGUILERA ANABELLA; RICARDO ECHENIQUE; GRACIELA SALERNO
Lugar:
Mar del Plata
Reunión:
Congreso; X Congreso Argentino de Microbiología General SAMIGE; 2014
Resumen:
Under certain environmental conditions, some cyanobacteria (Cyanophytes, Cyanoprokaryotes, also known as blue-green algae) are capable of growing rapidly and form harmful blooms (CHABs), phenomena that consists in a rapid increase in the density of one or two species that dominate the phytoplankton. The major problem associated with CHABs is that many species are capable of producing toxic compounds called cyanotoxins that constitute a health-risk for human beings worldwide via recreational and drinking water. In Argentina, the potential public health risk due to exposure to CHABs has grown in the last decades. In this study, we report the presence of Raphidiopsis mediterranea (Nostocales) and Planktothrix agardhii (Oscillatoriales) in Los Patos shallow lake, a small eutrophic reservoir located on Ensenada city, 60 Km South-West of Buenos Aires city (34º 50´ 44´´S, 57º 57´ 26´´W). Both species are known to co-occur in eutrophic shallow lakes and have been reported in other Argentinean freshwater bodies. One strain of each species was isolated and grown in MLA medium. Morphological traits of the two strains were analyzed by light microscopy and transmission electron microscope. Molecular analyses were performed using the sequences of the 16S rRNA gene and the cpcBA-IGS region, which includes the highly variable intergenic spacer (IGS) region between two phycobilisome (bilin) sub-units genes (cpcB and cpcA). R. mediterranea has been associated with the production of several cyanotoxins, such as homoanatoxin-a, anatoxin-a and cylindrospermopsin, while P. agardhii is known to synthesize microcystins. Thus, we investigated the presence of genes related with microcystin (MYC) and cylindrospermopsin (CYN) production by using primers specially designed for Planktothrix and Raphidiopsis, respectively. Isolated strains were successfully cultured on MLA medium and are now part of the culture collection of the FIBA-INBIOTEC laboratory. The identification of the strains as P. agardhii and R. mediterranea by morphological characterization was also supported by phylogenetic analyses. PCR analyses of P. agardhii were positive for the microcystin synthetase gene E (mcyE), whereas the cyrC gen, involved in CYN production, was absent in R. mediterranea. This it is the first report on the molecular characterization of filamentous bloom forming cyanobacteria native from Argentina.