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 Google Scholar
Google Scholar
Right arrow Articles by Bruckner, C. G.
Right arrow Articles by Kroth, P. G.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Bruckner, C. G.
Right arrow Articles by Kroth, P. G.
Agricola
Right arrow Articles by Bruckner, C. G.
Right arrow Articles by Kroth, P. G.

 Previous Article  |  Next Article 

Applied and Environmental Microbiology, December 2008, p. 7740-7749, Vol. 74, No. 24
0099-2240/08/$08.00+0     doi:10.1128/AEM.01399-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Bacteria Associated with Benthic Diatoms from Lake Constance: Phylogeny and Influences on Diatom Growth and Secretion of Extracellular Polymeric Substances{triangledown}

Christian G. Bruckner,1,{dagger} Rahul Bahulikar,1,{dagger},{ddagger} Monali Rahalkar,2,{ddagger} Bernhard Schink,2* and Peter G. Kroth1

Plant Ecophysiology,1 Microbial Ecology, Fachbereich Biologie, Universität Konstanz, Germany2

Received 23 June 2008/ Accepted 9 October 2008

The composition of diatom-associated bacterial communities was studied with 14 different unialgal xenic diatom cultures isolated from freshwater epilithic biofilms of Lake Constance, Germany. A clear dominance of Alphaproteobacteria was observed, followed by Betaproteobacteria, Gammaproteobacteria, Bacteroidetes, and Verrucomicrobia. Pure cultures of the diatom Cymbella microcephala, which was found to be dominant in epilithic biofilms in Lake Constance, were cocultivated with six associated bacterial strains. All these bacterial strains were able to grow in C. microcephala cultures in the absence of organic cosubstrates. Diatom growth was generally enhanced in the presence of bacteria, and polysaccharide secretion was generally increased in the presence of Proteobacteria. The monomer composition of extracellular polysaccharides of C. microcephala changed in relation to the presence of different bacteria, but the dominant monomers were less affected. Our results indicate that these changes were caused by the diatom itself rather than by specific bacterial degradation. One Bacteroidetes strain strongly influenced carbohydrate secretion by the alga via extracellular soluble compounds. Biofilms were formed only in the presence of bacteria. Phylogenetic analysis and coculture studies indicate an adaptation of Proteobacteria and Bacteroidetes to the microenvironment created by the diatom biofilm.

* Corresponding author. Mailing address: Fachbereich Biologie, Universität Konstanz, D-78457 Konstanz, Germany. Phone: 49 (7531) 882140. Fax: 49 (7531) 884047. E-mail: Bernhard.Schink{at}uni-konstanz.de

{triangledown} Published ahead of print on 17 October 2008.

{dagger} C.G.B. and R.B. contributed equally to this work.

{ddagger} Present address: Allgemeine Mikrobiologie, Universität Bremen, Postfach 330440, D-28334 Bremen, Germany.

Applied and Environmental Microbiology, December 2008, p. 7740-7749, Vol. 74, No. 24
0099-2240/08/$08.00+0     doi:10.1128/AEM.01399-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.





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