Competition for light between toxic and nontoxic strains of the harmful Cyanobacterium Microcystis

Kardinaal, W. Edwin A., Tonk, Linda, Janse, Ingmar, Hol, Suzanne, Slot, Pieter, Huisman, Jef and Visser, Petra M. (2007) Competition for light between toxic and nontoxic strains of the harmful Cyanobacterium Microcystis. Applied and Environmental Microbiology, 73 9: 2939-2946. doi:10.1128/AEM.02892-06

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Author Kardinaal, W. Edwin A.
Tonk, Linda
Janse, Ingmar
Hol, Suzanne
Slot, Pieter
Huisman, Jef
Visser, Petra M.
Title Competition for light between toxic and nontoxic strains of the harmful Cyanobacterium Microcystis
Formatted title
Competition for light between toxic and nontoxic strains of the harmful Cyanobacterium Microcystis
Journal name Applied and Environmental Microbiology   Check publisher's open access policy
ISSN 0099-2240
1098-5336
Publication date 2007-05
Sub-type Article (original research)
DOI 10.1128/AEM.02892-06
Open Access Status File (Publisher version)
Volume 73
Issue 9
Start page 2939
End page 2946
Total pages 8
Editor L. Nicholson Ornston
Place of publication Washington, DC, U.S.A.
Publisher American Society for Microbiology
Language eng
Subject 0605 Microbiology
Abstract The cyanobacterium Microcystis can produce microcystins, a family of toxins that are of major concern in water management. In several lakes, the average microcystin content per cell gradually declines from high levels at the onset of Microcystis blooms to low levels at the height of the bloom. Such seasonal dynamics might result from a succession of toxic to nontoxic strains. To investigate this hypothesis, we ran competition experiments with two toxic and two nontoxic Microcystis strains using light-limited chemostats. The population dynamics of these closely related strains were monitored by means of characteristic changes in light absorbance spectra and by PCR amplification of the rRNA internal transcribed spacer region in combination with denaturing gradient gel electrophoresis, which allowed identification and semiquantification of the competing strains. In all experiments, the toxic strains lost competition for light from nontoxic strains. As a consequence, the total microcystin concentrations in the competition experiments gradually declined. We did not find evidence for allelopathic interactions, as nontoxic strains became dominant even when toxic strains were given a major initial advantage. These findings show that, in our experiments, nontoxic strains of Microcystis were better competitors for light than toxic strains. The generality of this finding deserves further investigation with other Microcystis strains. The competitive replacement of toxic by nontoxic strains offers a plausible explanation for the gradual decrease in average toxicity per cell during the development of dense Microcystis blooms.
Keyword Cyanobacterium Microcystis
Microcystins
Water management
Microcystis blooms
Nontoxic strains
Q-Index Code C1

Document type: Journal Article
Sub-type: Article (original research)
Collections: Excellence in Research Australia (ERA) - Collection
Centre for Marine Studies Publications
 
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