15N-amino sugar stable isotope probing (15N-SIP) to trace the assimilation of fertiliser-N by soil bacterial and fungal communities
15N-amino sugar stable isotope probing (15N-SIP) to trace the assimilation of fertiliser-N by soil bacterial and fungal communities
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DOI：
10.1016/j.soilbio.2019.107599
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发表时间：
2019-11
影响因子：
9.7
通讯作者：
M. Reay;A. Charteris;Davey L. Jones;R. Evershed
中科院分区：
文献类型：
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作者：
M. Reay;A. Charteris;Davey L. Jones;R. Evershed
虽然氨基糖是土壤有机氮（ON）的主要组成部分，但土壤细菌和真菌将硝酸盐（NO3-）和铵（NH 4+）同化为氨基糖（AS）是全球氮循环中被忽视的一个方面。更深入地了解AS对氮肥添加的反应可能有助于提高农业系统内的氮素利用效率（NUE）。我们的目的是扩展一个敏感的compound-specific 15 N-稳定同位素探测（SIP）的方法开发的氨基酸（AAs），无机N固定到一系列的氨基糖（胞壁酸，葡萄糖胺，半乳糖胺，甘露糖胺）。在实验室培养条件下，以农业相关比例（15 NH 4+和15 NO3-分别为190和100 kg N ha− 1）施用15 N-铵和15 N-硝酸盐，以获得32 d内草原土壤AS库中N同化的定量测量。利用气相色谱-燃烧-同位素比值质谱（GC-C-IRMS），我们发现，δ 15 N值的个别AS反映了不同的路由所施加的铵和硝酸盐。对比细菌和真菌群落的N-同化动力学表现出通过测定的15 N掺入诊断AS。N-同化动力学的细菌群落的改变与应用基板，而真菌N-同化动力学不受影响。速率和通量的应用N-底物到细菌AS池反映了已知的AS的生物合成途径，与真菌葡糖胺似乎是生物合成进一步从应用的基板比细菌葡糖胺由于不同的周转率。这种敏感和特定的化合物特异性15 N-SIP方法使用AS，建立在现有的方法与AA，使微生物群落内的N-同化动力学的分化和微生物NUE与农业相关的施肥率的评估。
Although amino sugars represent a major component of soil organic nitrogen (ON), the assimilation of nitrate (NO3−) and ammonium (NH4+) into amino sugars (AS) by soil bacteria and fungi represents a neglected aspect of the global N cycle. A deeper knowledge of AS responses to N fertiliser addition may help enhance N use efficiency (NUE) within agricultural systems. Our aim was to extend a sensitive compound-specific15N-stable isotope probing (SIP) approach developed for amino acids (AAs) to investigate the immobilization of inorganic N into a range of amino sugars (muramic acid, glucosamine, galactosamine, mannosamine). Laboratory incubations using15N-ammonium and15N-nitrate applied at agriculturally relevant rates (190 and 100 kg N ha−1for15NH4+and15NO3−, respectively) were carried out to obtain quantitative measures of N-assimilation into the AS pool of a grassland soil over a 32-d period. Using gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) we found that δ15N values for individual AS reflected differences in routing of the applied ammonium and nitrate. The contrasting N-assimilation dynamics of bacterial and fungal communities were demonstrated through determinations of percentage15N incorporation into diagnostic AS. N-assimilation dynamics of the bacterial community were altered with the applied substrate whilst fungal N-assimilation dynamics were unaffected. Rates and fluxes of the applied N-substrates into the bacterial AS pool reflected known biosynthetic pathways for AS, with fungal glucosamine appearing to be biosynthetically further from the applied substrates than bacterial glucosamine due to different turnover rates. This sensitive and specific compound-specific15N-SIP approach using AS, building on existing approaches with AAs, enables differentiation of N-assimilation dynamics within the microbial community and assessment of microbial NUE with agriculturally relevant fertilisation rates.