Molecular and phylogenetic characterization of potentially toxic cyanobacteria in Tunisian freshwaters |
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Authors: | Fathalli Afef Jenhani Amel Ben Rejeb Moreira Cristiana Welker Martin Romdhane Mohamed Antunes Agostinho Vasconcelos Vitor |
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Affiliation: | a Unité de Recherche Ecosystèmes et Ressources Aquatiques, Institut National Agronomique de Tunisie, 43, Avenue Charles-Nicolle, 1082 Tunis Mahrajène, Tunisia;b Centro Interdisciplinar de Investigação Marinha e Ambiental-CIIMAR/CIMAR, Rua dos Bragas, 289, 4050-123 Porto, Portugal;c AnagnosTec GmbH, Am Mühlenberg 11, 14476 Potsdam, Germany;d FG Umweltmikrobiologie, Technische Universität Berlin, Franklinstr. 29, 10587 Berlin, Germany;e Departamento de Biologia, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal |
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Abstract: | This study presents a genetic characterization of 27 potentially toxic cyanobacterial strains isolated from seven reservoirs located in the north and centre of Tunisia. These strains belonged mainly to Microcystis aeruginosa, Cylindrospermopsis raciborskii and Planktothrix agardhii species. Their toxicological potential was evaluated by molecular biology tools, which showed that none of the isolated strains carried segments of the gene cluster responsible for the production of cylindrospermopsin and saxitoxin. The majority of Microcystis isolates were able to synthesize microcystin, since they presented the six characteristic segments of the microcystin synthetase mcy cluster (mcyA, -B, -C, -D, -E and -G). This was further confirmed by MALDI-TOF analysis that showed the presence of eight microcystin variants, including microcystin-LR. The taxonomic identification of the strains was assessed based on the variability of the 16S rRNA gene sequences. Furthermore, the 16S-23S rRNA ITS sequences of Microcystis isolates and rpoC1 sequences of Cylindrospermopsis strains were also used in the phylogenetic analysis. |
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Keywords: | Cyanobacteria Cyanotoxins Microcystins Phylogeny Tunisia |
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