title: Potassium sensitivity differs among strains of the harmful cyanobacterium Microcystis and correlates with the presence of salt tolerance genes.
abstract: Microcystis aeruginosa is a ubiquitous harmful cyanobacterium that causes problems in eutrophic lakes. Potassium ion (K(+)) addition is one of the suggested methods to combat harmful cyanobacterial blooms. To investigate the effectiveness of this method, we compared the potassium ion sensitivity of four Microcystis strains. Microcystis strains PCC 7005 and NIES-843 were very susceptible to potassium ion concentrations of ∼ 12 mmol L(-1), whereas strain PCC 7806 and its non-toxic mutant PCC 7806 ΔmcyB were not affected by added potassium ions. The origin of the strain appears to be of importance. Strain PCC 7806 originates from brackish water and possesses genes for the synthesis of the compatible solute sucrose, the water channel protein gene aqpZ and the sodium influx gene nhaS2, whereas strains PCC 7005 and NIES-843 have a freshwater origin and lack these genes. We conclude that potassium ion addition will not be a successful mitigation strategy in brackish waters, but may temporarily suppress Microcystis blooms in freshwater lakes. However, in the long run other Microcystis strains or other cyanobacteria with a higher salt tolerance will likely take over. In addition, our results also have implications for the potassium ion concentrations of mineral media used in laboratory studies with cyanobacteria.
authors.affiliation: Department of Aquatic Microbiology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, PO Box 94248, 1090 GE Amsterdam, the Netherlands.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Sandrini
authors.affiliation: Department of Aquatic Microbiology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, PO Box 94248, 1090 GE Amsterdam, the Netherlands.
authors.forename: Jef
authors.initials: J
authors.lastname: Huisman
authors.affiliation: Department of Aquatic Microbiology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, PO Box 94248, 1090 GE Amsterdam, the Netherlands j.c.p.matthijs@uva.nl.
authors.forename: Hans C P
authors.initials: HC
authors.lastname: Matthijs
mesh_terms: D004269:DNA, Bacterial / Q000235:genetics; D005798:Genes, Bacterial; D016680:Genome, Bacterial; D046931:Microcystis / Q000187:drug effects / Q000235:genetics* / Q000472:pathogenicity / Q000502:physiology*; D011188:Potassium / Q000494:pharmacology*; D055049:Salt Tolerance / Q000235:genetics*; D012621:Seasons; D014871:Water Microbiology
chemical_list: D004269:DNA, Bacterial; D011188:Potassium
keywords: compatible solutes; cyanobacteria; harmful algal blooms; lake mitigation; microcystins; salt stress