Soil microbial organic nitrogen uptake is regulated by carbon availability
Soil microbial organic nitrogen uptake is regulated by carbon availability
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DOI：
10.1016/j.soilbio.2014.07.003
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发表时间：
2014-10-01
影响因子：
9.7
通讯作者：
Condron, Leo M.
中科院分区：
文献类型：
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作者：
Farrell, Mark;Prendergast-Miller, Miranda;Condron, Leo M.
在陆地氮循环的许多阶段，植物和微生物都在激烈地竞争氮。特别是，溶解有机氮（DON）库，和竞争低分子量溶解有机氮（LMWDON）化合物，如氨基酸和肽（和LMW溶解有机物; LMWDOM作为一个整体）已收到显着的最近的研究兴趣。然而，由于LMWDON化合物含有N和碳（C），因此仍然存在的问题是土壤微生物主要是为了其中所含的C还是N而摄取LMWDON。我们研究了微生物的吸收率的模型肽L-三丙氨酸作为一个快速循环的LMWDON化合物在温带草原土壤的不同肥力使用C-14标记，以评估土壤肥力状况如何影响微生物吸收LMWDON。然后，我们施加过量的C作为葡萄糖和/或N作为NH 4Cl，以询问肽的摄取是否受到C或N过量的影响。我们的结果表明，L-三丙氨酸从土壤溶液中被迅速吸收（t（1/2），< 1.5 min），并且过量的C而不是N导致肽的吸收减少。由此，我们得出结论，LMWDON主要是为了满足土壤微生物的C需求，这表明它们存在于C限制状态，并且能够快速响应易代谢资源的瞬时涌入。(C)2014作者爱思唯尔有限公司出版
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.