Document Detail


Pulsed nitrogen supply induces dynamic changes in the amino acid composition and microcystin production of the harmful cyanobacterium Planktothrix agardhii.
MedLine Citation:
PMID:  20735475     Owner:  NLM     Status:  In-Process    
Abstract/OtherAbstract:
Planktothrix agardhii is a widespread harmful cyanobacterium of eutrophic waters, and can produce the hepatotoxins [Asp(3)]microcystin-LR and [Asp(3)]microcystin-RR. These two microcystin variants differ in their first variable amino acid position, which is occupied by either leucine (L) or arginine (R). Although microcystins are extensively investigated, little is known about the mechanisms that determine the production of different microcystin variants. We hypothesize that enhanced nitrogen availability will increase the intracellular content of the nitrogen-rich amino acid arginine, and thereby promote the production of the variant [Asp(3)]microcystin-RR. To test this hypothesis, we transferred P. agardhii strain 126/3 from nitrogen-replete to nitrogen-deficient conditions, and after 2 weeks of growth under nitrogen deficiency, we added a nitrogen pulse. We found a rapid increase in the cellular nitrogen to carbon ratio and the amino acids aspartic acid and arginine, indicative of cyanophycin synthesis. This was followed by a more gradual increase of the total amino acid content connected to balanced growth. As expected, the [Asp(3)]microcystin-RR variant increased strongly after the nitrogen pulse, while the [Asp(3)]microcystin-LR increased to a much lesser extent. We conclude that sudden nitrogen enrichment affects the amino acid composition of harmful cyanobacteria, which, in turn, affects the production and composition of their microcystins.
Authors:
Dedmer B Van de Waal; Gonzalo Ferreruela; Linda Tonk; Ellen Van Donk; Jef Huisman; Petra M Visser; Hans C P Matthijs
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2010-08-23
Journal Detail:
Title:  FEMS microbiology ecology     Volume:  74     ISSN:  1574-6941     ISO Abbreviation:  FEMS Microbiol. Ecol.     Publication Date:  2010 Nov 
Date Detail:
Created Date:  2010-11-02     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8901229     Medline TA:  FEMS Microbiol Ecol     Country:  England    
Other Details:
Languages:  eng     Pagination:  430-8     Citation Subset:  IM    
Copyright Information:
© 2010 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.
Affiliation:
Aquatic Microbiology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands.
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