Journal
SOIL BIOLOGY & BIOCHEMISTRY
Volume 77, Issue -, Pages 261-267Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.soilbio.2014.07.003
Keywords
Peptide; Grassland soil; C-14; Rapid uptake; Nutrient limitation; Dissolved organic nitrogen
Categories
Funding
- CSIRO Sustainable Agriculture Flagship
- UK Natural Environment Research Council [NE/1012303/1]
- Natural Environment Research Council [NE/I012303/1] Funding Source: researchfish
- NERC [NE/I012303/1] Funding Source: UKRI
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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 C-14 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 (t(1/2), < 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. (C) 2014 The Authors. Published by Elsevier Ltd.
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