Glaser Bruno, Gross Simone
Institute of Soil Science and Soil Geography, University of Bayreuth, D-95440 Bayreuth, Germany.
Rapid Commun Mass Spectrom. 2005;19(11):1409-16. doi: 10.1002/rcm.1913.
There is strong scientific evidence that microbial residues such as amino sugars may be stabilized in soil. However, up to now, no investigation has been carried out to quantify both the amount and timing of such stabilization. This is primarily due to methodological constraints, because it is not possible to differentiate between stabilized (old) and recently produced (new) amino sugars when these biomarkers are conventionally analyzed, e.g. by means of gas chromatography and flame ionization detection. Therefore, the aim of the present study was to test whether compound-specific isotope analysis (delta13C) of amino sugars extracted from soil could be used to differentiate between old and new microbial residues. For this aim a method for the delta13C analysis of individual amino sugars was developed and optimized. First results of delta13C values of glucosamine, galactosamine, mannosamine, and muramic acid in soil samples from two different ecological studies are presented, clearly indicating that discrimination between soil inherent and newly formed amino sugars is possible in stable isotope labeling experiments. Our results further showed that, in the short term (within 1 month), only few amino sugars were built, thus making highly 13C-enriched substrates necessary for the quantification of new amino sugar production and for the determination of amino sugar turnover rates.
有充分的科学证据表明，微生物残体（如氨基糖）可能在土壤中被稳定下来。然而，到目前为止，尚未开展任何研究来量化这种稳定作用的数量和时间。这主要是由于方法上的限制，因为在对这些生物标志物进行常规分析（例如通过气相色谱和火焰离子化检测）时，无法区分稳定的（旧的）和新产生的（新的）氨基糖。因此，本研究的目的是测试从土壤中提取的氨基糖的化合物特异性同位素分析（δ13C）是否可用于区分旧的和新的微生物残体。为了实现这一目标，开发并优化了一种用于单个氨基糖δ13C分析的方法。本文给出了来自两项不同生态研究的土壤样品中葡萄糖胺、半乳糖胺、甘露糖胺和胞壁酸的δ13C值的初步结果，清楚地表明在稳定同位素标记实验中区分土壤固有和新形成的氨基糖是可能的。我们的结果还表明，在短期内（1个月内），只有少量氨基糖生成，因此需要使用高度富集13C的底物来量化新氨基糖的产生并确定氨基糖的周转率。
