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Article

Influence of Environmental Factors on Occurrence of Cyanobacteria and Abundance of Saxitoxin-Producing Cyanobacteria in a Subtropical Drinking Water Reservoir in Brazil

1
Department of Hydraulics and Sanitation, São Carlos School of Engineering, University of São Paulo, 400 Trabalhador São Carlense Avenue, São Carlos 13566-590, Brazil
2
Environment and Toxicology, DHI, Agern Alle 5, 2970 Hørsholm, Denmark
3
Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg, Denmark
*
Author to whom correspondence should be addressed.
Academic Editor: Katarzyna Kowalczewska-Madura
Water 2021, 13(12), 1716; https://doi.org/10.3390/w13121716
Received: 14 May 2021 / Revised: 12 June 2021 / Accepted: 17 June 2021 / Published: 21 June 2021
(This article belongs to the Special Issue Water Quality Changes of Lakes and Rivers)
Blooms of cyanobacteria are frequent in Brazilian water reservoirs used for drinking water. The warning for the presence of potential toxin-producing cyanobacteria is typically based on time-consuming microscopy, rather than specific molecular detection of toxic genes in cyanobacteria. In this study, we developed a quantitative PCR assay for the detection of cyanobacteria producing the neurotoxin saxitoxin (STX). The assay targets the sxtA gene in the sxt gene cluster. Potential and dominant STX-producers in the Itupararanga reservoir were the genera Raphidiopsis, Aphanizomenon and Geitlerinema. Numbers of the sxtA gene varied from 6.76 × 103 to 7.33 × 105 cells mL−1 and correlated positively with SXT concentrations in the water. Concentrations of STX and the sxtA gene also correlated positively with TN:TP ratio and pH, but correlated negatively with inorganic nutrients and turbidity, confirming that regulation of the SXT production was impacted by environmental variables. In contrast, the occurrence of another cyanotoxin, microcystin, did not correlate with any environmental variables. The developed qPCR assay was found to be a rapid and robust approach for the specific quantification of potential STX-producing cyanobacteria and should be considered in future investigations on toxic cyanobacteria to provide an early warning of potential toxin episodes. View Full-Text
Keywords: Itupararanga reservoir; toxic cyanobacteria; cyanotoxins; qPCR; sxtA Itupararanga reservoir; toxic cyanobacteria; cyanotoxins; qPCR; sxtA
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MDPI and ACS Style

Moraes, M.A.B.; Rodrigues, R.A.M.; Schlüter, L.; Podduturi, R.; Jørgensen, N.O.G.; Calijuri, M.C. Influence of Environmental Factors on Occurrence of Cyanobacteria and Abundance of Saxitoxin-Producing Cyanobacteria in a Subtropical Drinking Water Reservoir in Brazil. Water 2021, 13, 1716. https://doi.org/10.3390/w13121716

AMA Style

Moraes MAB, Rodrigues RAM, Schlüter L, Podduturi R, Jørgensen NOG, Calijuri MC. Influence of Environmental Factors on Occurrence of Cyanobacteria and Abundance of Saxitoxin-Producing Cyanobacteria in a Subtropical Drinking Water Reservoir in Brazil. Water. 2021; 13(12):1716. https://doi.org/10.3390/w13121716

Chicago/Turabian Style

Moraes, Munique A.B., Raphaella A.M. Rodrigues, Louise Schlüter, Raju Podduturi, Niels O.G. Jørgensen, and Maria C. Calijuri 2021. "Influence of Environmental Factors on Occurrence of Cyanobacteria and Abundance of Saxitoxin-Producing Cyanobacteria in a Subtropical Drinking Water Reservoir in Brazil" Water 13, no. 12: 1716. https://doi.org/10.3390/w13121716

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