Publicaciones del III Congreso Ibérico de Cianotoxinas (Blanes, 2013)The study and monitoring of cyanobacterial blooms often involves the use of preserved samples to avoid cellular degradation.
However, preserved samples may not be suitable for molecular biology studies because preservation methods can interfere
with DNA quality/quantity. Real-time quantitative PCR analysis (qPCR) has been widely applied in molecular analysis and
is considered a promising method for monitoring purposes. This study intended to evaluate the applicability of the real-time
qPCR technique in samples that were subjected to different methods of preservation: (1) 15% Lugol’s iodine solution (2) 4%
formaldehyde and (3) 25% glutaraldehyde. The ability to amplify and quantify DNA extracted from Planktothrix agardhii
was assessed using the rpoC1 gene as the target fragment in both raw water samples and in vitro cultures.
No reliable DNA amplification was obtained from glutaraldehyde-preserved samples. Successful amplification was obtained
from Lugol’s and formaldehyde-preserved samples. In this case, however, the quantification that was achieved by real-time
PCR cannot be used to infer cell numbers, because the Ct values that were obtained from the Lugol’s and formaldehydepreserved samples were significantly higher than the Ct values that were obtained from the unpreserved samples. Therefore
real-time PCR can be used for the detection and identification of cyanobacteria in preserved samples but no reliable cell
quantification can be performed using this method.This research was supported by the Fundação para Ciência e Tecnologia, Portugal (FCT)
through the project PPCDT/AMB/67075/2006.
The authors also acknowledge the PhD research grant SFRH/BD65706/2009 to C. Churro and the Post-Doc research grant SFRH/BPD/75922/2011
to E. Valério
