Temporal effect of straw addition on amino acid utilization by soil microorganisms
Temporal effect of straw addition on amino acid utilization by soil microorganisms
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DOI：
10.1016/j.ejsobi.2012.09.006
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发表时间：
2012-11-01
影响因子：
4.2
通讯作者：
Ludwig, Bernard
中科院分区：
文献类型：
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作者：
Geisseler, Daniel;Joergensen, Rainer Georg;Ludwig, Bernard
微生物可以直接吸收含有有机分子的简单氮(N)，也可以先对其脱氨，然后吸收释放出来的铵。本研究旨在探讨秸秆入土对土壤微生物氮吸收途径的影响。土壤样品在20℃下添加和不添加秸秆孵育84 d。用n -15标记的氨基酸测定氨基酸的矿化率。在第一周内，秸秆的添加导致净氮的固定和矿物氮库的枯竭。添加的氨基酸在24 h内被矿化或被土壤微生物吸收。第1周添加的氨基酸矿化比例较低，说明70 ~ 95%的氨基酸被直接吸收。不断增长的微生物群落需要氨基酸来合成蛋白质，这可能有利于它们的直接摄取。第1周后，矿化率增加，直接吸收量仅占60-70%。我们的研究结果表明，直接吸收有机氮通常是首选途径，但当氮严重限制时，胞外氨化可能是一个重要的替代途径。(C) 2012 Elsevier Masson SAS。版权所有。
Microorganisms may take up simple nitrogen (N) containing organic molecules directly or they may deaminate them first and take up the ammonium released. The present study was carried out to investigate how the incorporation of straw into soil affects the N uptake pathway of soil microorganisms. Soil samples were incubated for 84 days at 20 degrees C with and without straw addition. The mineralization rate of amino acids was determined using N-15-labeled amino acids. The addition of straw resulted in net N immobilization and the depletion of the mineral N pool during the first week. Added amino acids were either mineralized or taken up by soil microorganisms within 24 h of their addition. The proportion of added amino acids mineralized during the first week was low, suggesting that 70-95% of the added amino acids were taken up directly. The need for amino acids for the synthesis of proteins for the growing microbial community likely favored their direct uptake. After the first week however, the mineralization rate increased and the direct uptake accounted for only 60-70%. Our results suggest that the direct uptake of organic N was generally the preferred pathway, but that the extracellular ammonification may be an important alternative when N is severely limiting. (C) 2012 Elsevier Masson SAS. All rights reserved.