AEM
Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow An author's correction has been published
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 arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Avrahami, S.
Right arrow Articles by Braker, G.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Avrahami, S.
Right arrow Articles by Braker, G.
Agricola
Right arrow Articles by Avrahami, S.
Right arrow Articles by Braker, G.
Applied and Environmental Microbiology, November 2002, p. 5685-5692, Vol. 68, No. 11
0099-2240/02/$04.00+0     DOI: 10.1128/AEM.68.11.5685-5692.2002
Copyright © 2002, American Society for Microbiology. All Rights Reserved.

Effect of Soil Ammonium Concentration on N2O Release and on the Community Structure of Ammonia Oxidizers and Denitrifiers

Sharon Avrahami, Ralf Conrad, and Gesche Braker*

Max-Planck-Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse, 35043 Marburg, Germany

Received 30 May 2002/ Accepted 6 August 2002

The effect of ammonium addition (6.5, 58, and 395 µg of NH4+-N g [dry weight] of soil-1) on soil microbial communities was explored. For medium and high ammonium concentrations, increased N2O release rates and a shift toward a higher contribution of nitrification to N2O release occurred after incubation for 5 days at 4°C. Communities of ammonia oxidizers were assayed after 4 weeks of incubation by denaturant gradient gel electrophoresis (DGGE) of the amoA gene coding for the small subunit of ammonia monooxygenase. The DGGE fingerprints were invariably the same whether the soil was untreated or incubated with low, medium, or high ammonium concentrations. Phylogenetic analysis of cloned PCR products from excised DGGE bands detected amoA sequences which probably belonged to Nitrosospira 16S rRNA clusters 3 and 4. Additional clones clustered with Nitrosospira sp. strains Ka3 and Ka4 and within an amoA cluster from unknown species. A Nitrosomonas-like amoA gene was detected in only one clone. In agreement with the amoA results, community profiles of total bacteria analyzed by terminal restriction fragment length polymorphism (T-RFLP) showed only minor differences. However, a community shift occurred for denitrifier populations based on T-RFLP analysis of nirK genes encoding copper-containing nitrite reductase with incubation at medium and high ammonia concentrations. Major terminal restriction fragments observed in environmental samples were further described by correspondence to cloned nirK genes from the same soil. Phylogenetic analysis grouped these clones into clusters of soil nirK genes. However, some clones were also closely related to genes from known denitrifiers. The shift in the denitrifier community was probably the consequence of the increased supply of oxidized nitrogen through nitrification. Nitrification activity increased upon addition of ammonium, but the community structure of ammonium oxidizers did not change.

* Corresponding author. Mailing address: Max-Planck-Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse, D-35043 Marburg, Germany. Phone: 06421/178 810. Fax: 06421/178 999. E-mail: braker{at}mailer.uni-marburg.de.

Applied and Environmental Microbiology, November 2002, p. 5685-5692, Vol. 68, No. 11
0099-2240/02/$04.00+0     DOI: 10.1128/AEM.68.11.5685-5692.2002
Copyright © 2002, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:



Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
J. Bacteriol. Microbiol. Mol. Biol. Rev. Eukaryot. Cell All ASM Journals

Copyright © 2002 by the American Society for Microbiology. All rights reserved.