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:
A. AGUILERA; R. ECHENIQUE; G.L. SALERNO
Lugar:
Mar del Plata
Reunión:
Congreso; X Congreso Argentino de Microbiología General; 2014
Institución organizadora:
Sociedad Argentina de Microbiología General
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.