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Soil microbial organic nitrogen uptake is regulated by carbon availability

Farrell, M. and Prendergast-Miller, M. and Jones, D.L. and Hill, P.W. and Condron, L.M. (2014) Soil microbial organic nitrogen uptake is regulated by carbon availability. Soil Biology and Biochemistry, 77. pp. 261-267. DOI: 10.1016/j.soilbio.2014.07.003

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Abstract

Plants and microorganisms intensely compete for nitrogen (N) at many stages of the terrestrial N cycle. In particular, the dissolved organic N (DON) pool, and competition for low molecular weight dissolved organic N (LMWDON) compounds such as amino acids and peptides (and LMW dissolved organic matter; LMWDOM as a whole) has received significant recent research interest. However, as LMWDON compounds contain both N and carbon (C), a question that remains is whether soil microorganisms are primarily taking up LMWDON mainly for the C or the N contained therein. We investigated microbial uptake rates of the model peptide l-trialanine as a rapidly cycling LMWDON compound in temperate grassland soils of differing fertility using 14C labelling to assess how soil fertility status influenced microbial uptake of LMWDON. We then imposed an excess of C as glucose and/or N as NH4Cl to ask whether the uptake of the peptide was affected by C or N excess. Our results demonstrate that l-trialanine is taken up rapidly from the soil solution (t½ < 1.5 min), and that an excess of C, rather than N, resulted in a reduced uptake of the peptide. From this, we conclude that LMWDON is taken up primarily to fulfil the C requirement of soil microorganisms, indicating that they exist in a C-limited state, and are able to respond quickly to a transient influx of an easily metabolisable resource.

Item Type: Article
Subjects: Research Publications
Departments: College of Natural Sciences > School of Environment, Natural Resources and Geography
Date Deposited: 17 Mar 2015 22:52
Last Modified: 23 Sep 2015 02:56
ISSN: 0038-0717
URI: http://e.bangor.ac.uk/id/eprint/3658
Identification Number: DOI: 10.1016/j.soilbio.2014.07.003
Publisher: Elsevier
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