This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Google Scholar
Right arrow Articles by de Werra, P.
Right arrow Articles by Maurhofer, M.
PubMed
Right arrow PubMed Citation
Right arrow Articles by de Werra, P.
Right arrow Articles by Maurhofer, M.
Agricola
Right arrow Articles by de Werra, P.
Right arrow Articles by Maurhofer, M.

 Previous Article  |  Next Article 

Applied and Environmental Microbiology, June 2009, p. 4162-4174, Vol. 75, No. 12
0099-2240/09/$08.00+0     doi:10.1128/AEM.00295-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

Role of Gluconic Acid Production in the Regulation of Biocontrol Traits of Pseudomonas fluorescens CHA0{triangledown}

Patrice de Werra,1 Maria Péchy-Tarr,2 Christoph Keel,2* and Monika Maurhofer1*

Institute of Integrative Biology, Plant Pathology, Swiss Federal Institute of Technology, CH-8092 Zurich,1 Department of Fundamental Microbiology, University of Lausanne, CH-1015 Lausanne, Switzerland2

Received 5 February 2009/ Accepted 13 April 2009

The rhizobacterium Pseudomonas fluorescens CHA0 promotes the growth of various crop plants and protects them against root diseases caused by pathogenic fungi. The main mechanism of disease suppression by this strain is the production of the antifungal compounds 2,4-diacetylphloroglucinol (DAPG) and pyoluteorin (PLT). Direct plant growth promotion can be achieved through solubilization of inorganic phosphates by the production of organic acids, mainly gluconic acid, which is one of the principal acids produced by Pseudomonas spp. The aim of this study was to elucidate the role of gluconic acid production in CHA0. Therefore, mutants were created with deletions in the genes encoding glucose dehydrogenase (gcd) and gluconate dehydrogenase (gad), required for the conversion of glucose to gluconic acid and gluconic acid to 2-ketogluconate, respectively. These enzymes should be of predominant importance for rhizosphere-colonizing biocontrol bacteria, as major carbon sources provided by plant root exudates are made up of glucose. Our results show that the ability of strain CHA0 to acidify its environment and to solubilize mineral phosphate is strongly dependent on its ability to produce gluconic acid. Moreover, we provide evidence that the formation of gluconic acid by CHA0 completely inhibits the production of PLT and partially inhibits that of DAPG. In the {Delta}gcd mutant, which does not produce gluconic acid, the enhanced production of antifungal compounds was associated with improved biocontrol activity against take-all disease of wheat, caused by Gaeumannomyces graminis var. tritici. This study provides new evidence for a close association of gluconic acid metabolism with antifungal compound production and biocontrol activity in P. fluorescens CHA0.

* Corresponding author. Mailing address for M. Maurhofer: Plant Pathology, Institute of Integrative Biology, Swiss Federal Institute of Technology, Universitätstrasse 2, CH-8092 Zürich, Switzerland. Phone: 41-44-632-3868. Fax: 41-44-632-1572. E-mail: monika.maurhofer{at}agrl.ethz.ch. Mailing address for C. Keel: Department of Fundamental Microbiology, Biophore Building, University of Lausanne, CH-1015 Lausanne, Switzerland. Phone: 41-21-692-5636. Fax: 41-21-692-5605. E-mail: christoph.keel{at}unil.ch

{triangledown} Published ahead of print on 17 April 2009.

Applied and Environmental Microbiology, June 2009, p. 4162-4174, Vol. 75, No. 12
0099-2240/09/$08.00+0     doi:10.1128/AEM.00295-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Guo, Y. B., Li, J., Li, L., Chen, F., Wu, W., Wang, J., Wang, H. (2009). Mutations That Disrupt Either the pqq or the gdh Gene of Rahnella aquatilis Abolish the Production of an Antibacterial Substance and Result in Reduced Biological Control of Grapevine Crown Gall. Appl. Environ. Microbiol. 75: 6792-6803 [Abstract] [Full Text]  


Copyright © 2009 by the American Society for Microbiology.   For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»