This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Supplementary material
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
Google Scholar
Right arrow Articles by Duarte, S.
Right arrow Articles by Charcosset, J.-Y.
PubMed
Right arrow PubMed Citation
Right arrow Articles by Duarte, S.
Right arrow Articles by Charcosset, J.-Y.
Agricola
Right arrow Articles by Duarte, S.
Right arrow Articles by Charcosset, J.-Y.

 Previous Article  |  Next Article 

Applied and Environmental Microbiology, October 2009, p. 6211-6221, Vol. 75, No. 19
0099-2240/09/$08.00+0     doi:10.1128/AEM.00971-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

Microbial Decomposer Communities Are Mainly Structured by Trophic Status in Circumneutral and Alkaline Streams{triangledown} ,{dagger}

Sofia Duarte,1* Cláudia Pascoal,1 Frédéric Garabétian,2 Fernanda Cássio,1 and Jean-Yves Charcosset2

Centre of Molecular and Environmental Biology (CBMA), Department of Biology, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal,1 EcoLab, Laboratoire d'Ecologie Fonctionnelle, UMR 5245 CNRS-UPS-INPT, Centre National de la Recherche Scientifique, 31055 Toulouse, France2

Received 28 April 2009/ Accepted 23 July 2009

In streams, the release of nitrogen and phosphorus is reported to affect microbial communities and the ecological processes they govern. Moreover, the type of inorganic nitrogen (NO3, NO2, or NH4) may differently impact microbial communities. We aimed to identify the environmental factors that structure aquatic microbial communities and drive leaf litter decomposition along a gradient of eutrophication. We selected five circumneutral (Portuguese) and five alkaline (French) streams differing in nutrient concentrations to monitor mass loss of alder leaves, bacterial and fungal diversity by PCR-denaturing gradient gel electrophoresis, fungal biomass and reproduction, and bacterial biomass during 11 weeks of leaf immersion. The concentrations of inorganic nutrients in the stream water ranged from 5 to 300 µg liter–1 soluble reactive phosphorus, 0.30 to 5.50 mg liter–1 NO3-N, 2 to 103 µg liter–1 NO2-N, and <4 to 7,100 µg liter–1 NH4-N. Species richness was maximum in moderately anthropized (eutrophic) streams but decreased in the most anthropized (hypertrophic) streams. Different species assemblages were found in subsets of streams with different trophic statuses. In both geographic areas, the limiting nutrient, either nitrate or phosphate, stimulated the microbial activity in streams of intermediate trophic status. In the hypertrophic streams, fungal biomass and reproduction were significantly lower, and bacterial biomass dramatically decreased at the site with the highest ammonium concentration. The limiting nutrients that defined the trophic status were the main factor structuring fungal and bacterial communities, whatever the geographic area. A very high ammonium concentration in stream water most probably has negative impacts on microbial decomposer communities.

* Corresponding author. Mailing address: Department of Biology, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal. Phone: 351 253604045. Fax: 351 253678980. E-mail: sduarte{at}bio.uminho.pt

{triangledown} Published ahead of print on 31 July 2009.

{dagger} Supplemental material for this article may be found at http://aem.asm.org/.

Applied and Environmental Microbiology, October 2009, p. 6211-6221, Vol. 75, No. 19
0099-2240/09/$08.00+0     doi:10.1128/AEM.00971-09
Copyright © 2009, 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»