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Evaluating the influence of light intensity in mcyA gene expression and microcystin production in toxic strains of Planktothrix agardhii and Microcystis aeruginosa

2016-04Journal article Restricted access
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dc.contributor.authorSalvador, Daniel
dc.contributor.authorChurro, Catarina
dc.contributor.authorValério, Elisabete
dc.date.accessioned2017-03-07T16:38:09Z
dc.date.available2021-02-04T01:30:09Z
dc.date.issued2016-04
dc.description.abstractCyanobacteria are phytoplanktonic organisms widely occurring in freshwaters, being frequently associated with the production of toxins, namely microcystins (MCs). MCs are produced non-ribosomally by a multienzyme complex (mcy genes). It has been reported that environmental factors, such as light intensity, can influence toxin production. The aim of this study was to assess the influence of light intensity in the transcription of the mcyA gene and corresponding production of microcystins in toxic isolates of Planktothrix agardhii, where little is known, and compare them to Microcystis aeruginosa. For that purpose, cultures were exposed to three different light intensities (4, 20 and 30 μmol photons m(-2) s(-1)) for 18 days at 20 ± 1 °C. The growth was followed daily using absorbance readings. Samples were collected at each growth stage for cell counting, microcystins quantification and RNA extraction. The level of transcripts was quantified by RT-qPCR and the relative expression determined using 16S rDNA, gltA and rpoC1 as reference genes. The most stable reference genes in M. aeruginosa were rpoC1 and gltA, whereas in P. agardhii were 16S rDNA and gltA. There was a correspondence between the growth rate and light intensity in M. aeruginosa and P. agardhii. The growth rates for both species were lower at 4 and higher at 30 μmol photons m(-2) s(-1). Microcystin concentration per cell was similar between light intensities in M. aeruginosa and over time, while in P. agardhii it was higher in the stationary phase at 4 μmol photons m(-2) s(-1). There were differences in the expression of mcyA between the two species. In M. aeruginosa, the highest levels of expression occurred at 4 μmol photons m(-2) s(-1) in the adaptation phase, whereas for P. agardhii it was at 4μmol photons m(-2) s(-1) in the exponential growth phase. Our results indicate that the light intensities tested had distinct influences on the growth, microcystin production and mcyA expression levels, presenting considerable differences in M. aeruginosa and P. agardhii.pt_PT
dc.description.sponsorshipThis research was partially supported by the European Regional Development Fund (ERDF) through the COMPETE – Operational Competitiveness Program – and FCT — Foundation for Science and Technology national funds through Ph.D research grant SFRH/ BD65706/2009 to C. Churro and Post-Doc research grant SFRH/BPD/ 75922/2011 to E. Valério.pt_PT
dc.description.versioninfo:eu-repo/semantics/publishedVersionpt_PT
dc.identifier.citationJ Microbiol Methods. 2016 Apr;123:4-12. doi: 10.1016/j.mimet.2016.02.002. Epub 2016 Feb 3pt_PT
dc.identifier.doi10.1016/j.mimet.2016.02.002pt_PT
dc.identifier.issn0167-7012
dc.identifier.urihttp://hdl.handle.net/10400.18/4552
dc.language.isoengpt_PT
dc.peerreviewedyespt_PT
dc.publisherElsevierpt_PT
dc.relation.publisherversionhttp://www.sciencedirect.com/science/article/pii/S0167701216300197pt_PT
dc.subjectBacterial Proteinspt_PT
dc.subjectCyanobacteriapt_PT
dc.subjectGene Expression Regulation, Bacterialpt_PT
dc.subjectLightpt_PT
dc.subjectMicrocystinspt_PT
dc.subjectMicrocystispt_PT
dc.subjectÁgua e Solopt_PT
dc.titleEvaluating the influence of light intensity in mcyA gene expression and microcystin production in toxic strains of Planktothrix agardhii and Microcystis aeruginosapt_PT
dc.typejournal article
dspace.entity.typePublication
oaire.citation.endPage12pt_PT
oaire.citation.startPage4pt_PT
oaire.citation.titleJournal of Microbiological Methodspt_PT
oaire.citation.volume123pt_PT
rcaap.rightsopenAccesspt_PT
rcaap.typearticlept_PT

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