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Open AccessArticle

Isolation and Characterization of Cylindrospermopsis raciborskii Strains from Finished Drinking Water

Department of Environmental Health, National Institute of Health Dr. Ricardo Jorge (INSA), Av. Padre Cruz, 1649-016 Lisbon, Portugal
Department of Sea and Marine Resources, Portuguese Institute for the Sea and Atmosphere (IPMA), Rua Alfredo Magalhães Ramalho, 6, 1495-006 Lisbon, Portugal
Centre for the Studies of Animal Science (CECA), Institute of Agrarian and Agri-Food Sciences and Technologies (ICETA), Oporto University, 4051-401 Oporto, Portugal
Author to whom correspondence should be addressed.
Toxins 2020, 12(1), 40;
Received: 21 November 2019 / Revised: 27 December 2019 / Accepted: 3 January 2020 / Published: 8 January 2020
In the summer of 2015, an intense cyanobacterial bloom producing geosmin/2-methylisoborneol (MIB) occurred in the Roxo freshwater reservoir in Alentejo, Portugal. The drinking water supplied from the Roxo water treatment plant (WTP) exhibited an unpleasant odor/taste and a significant cyanobacteria density was detected in the finished water at the exit of the WTP. Cyanobacteria were not evaluated downstream of the WTP, namely, at the city reservoir. The aim of this work was to isolate and characterize viable cyanobacteria present in finished water (exit of the WTP and city reservoir) that withstand conventional water treatment. Treated water samples collected at both sites were inoculated in Z8 culture medium to provide the conditions for putative cyanobacterial growth. After 30 days, filamentous cyanobacteria were observed in cultures inoculated with samples from the exit point of the WTP. Viable trichomes were isolated and identified as Cylindrospermopsis raciborskii by morphometric and molecular analysis. None of the isolates were cylindrospermopsin/microcystin producers, as confirmed by ELISA and amplification of corresponding genes (PS/PKS and mcyA-cd/mcyAB/mcyB). ELISA results were positive for saxitoxin, but saxitoxin and derivatives were not detected by liquid chromatography with fluorescence detection (LC-FLD), nor were their related genes (sxtA/sxtA4/sxtB/sxtM/sxtPer/sxtI). To our knowledge, this is the first report on the establishment of cultures of C. raciborskii that resisted water treatment processes. View Full-Text
Keywords: Cylindrospermopsis raciborskii; finished water; saxitoxin; culture collection Cylindrospermopsis raciborskii; finished water; saxitoxin; culture collection
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MDPI and ACS Style

Menezes, C.; Valério, E.; Botelho, M.J.; Dias, E. Isolation and Characterization of Cylindrospermopsis raciborskii Strains from Finished Drinking Water. Toxins 2020, 12, 40.

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