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篇目详细内容

【篇名】 Experimental strategies to measure the microbial uptake and mineralization kinetics of dissolved organic carbon in soil
【刊名】 Soil Ecology Letters
【刊名缩写】 Soil Ecology Letters
【ISSN】 2662-2289
【EISSN】 2662-2297
【DOI】 10.1007/s42832-020-0035-5
【出版社】
【出版年】 2020
【卷期】 2 卷3期
【页码】 180-187 页,共 8 页
【作者】 Baozhen Li; Tida Ge; Paul W. Hill; Davey L. Jones; Zhenke Zhu; Mostafa Zhran; Jinshui Wu;
【关键词】 14C tracer|Microbial uptake|Carbon mineralization|Turnover

【摘要】

Soil organic matter turnover rates are typically estimated from mass loss of the material over time or from on rates of carbon dioxide production. In the study, we investigated a new way to characterize the concentration-dependent kinetics of amino acids used by measuring microbial uptake and mineralization of 14C-alanine. We measured the depletion from soil solution after additions 14C-alanine. The microbial uptake of 14C-alanine from soil solution was concentration dependent and kinetic analysis indicated the operation of at least three distinct alanine transport systems of differing affinities. Most of the 14C-alanine depletion from the soil solution occurred rapidly within the first 10 – 30 min of the incubation after 10 μM to 1 mM substrate additions. At alanine concentrations less than 250 μM, the kinetic parameters for Km and Vmax of the higher-affinity transporter were 60.0 μM and 1.32 μmol g1 DW soil h1, respectively. The mineralization of alanine was determined and the half-time values for the rapid mineralization process were 45 min to 1.5 h after the addition at alanine concentrations below 1 mM. The time delay after its uptake into microbial biomass suggested that alanine uptake and subsequent respiration was uncoupled pattern. The microbial N uptake rate was calculated by microbial mineralization, and an estimated the Km value of 1731.7±274.6 μM and Vmax value of 486.0±38.5 μmol kg1 DW soil h1. This study provides an alternative approach for measuring the rate of turnover of compounds that turnover very rapidly in soil.

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