“Non-metabolizable” glucose analogue shines new light on priming mechanisms: Triggering of microbial metabolism
“Non-metabolizable” glucose analogue shines new light on priming mechanisms: Triggering of microbial metabolism
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DOI：
10.1016/j.soilbio.2016.12.015
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发表时间：
2017-04
影响因子：
9.7
通讯作者：
K. Mason-Jones;Y. Kuzyakov
中科院分区：
文献类型：
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作者：
K. Mason-Jones;Y. Kuzyakov
引发土壤有机质分解的研究引起了人们极大的兴趣，然而对这一现象的结论性机理解释仍然是难以捉摸的。一种观点认为，低分子量有机物质可能会“触发”微生物新陈代谢的加速。我们首次将葡萄糖类似物应用于土壤，以证明微生物代谢的触发，并估计其对引发的相对贡献。“非代谢”葡萄糖类似物已广泛用于纯培养研究以模拟葡萄糖，但从未用于土壤生物化学。我们假设，类似物分子将引发微生物的代谢反应，尽管有限的catalysts，从而证实了所提出的triggering.14 C-标记的3-O-甲基-D-葡萄糖（OMG）-一种常见的“非代谢”葡萄糖类似物-对土壤有机质矿化的影响进行了比较，14 C-标记的D-葡萄糖。OMG矿化，但其矿化最初受阻，大大延迟，相对于葡萄糖。OMG在前24 h引起短暂但强烈的启动，分别增加了0.49、2.4和4.9 μmol OMG g− 1土壤的未标记CO2排放量，分别比对照增加了173%、89%和36%。相反，葡萄糖在第一天引起低或负启动。在第一天OMG添加后，引发和OMG矿化之间的负相关性表明，触发是一个有效的机制，在饥饿-盛宴过渡期间的微生物激活，但短暂的。葡萄糖矿化的第二天达到峰值，为中等和高添加，在正引发的峰值相吻合。最大的底物矿化也正好在启动峰值为中等和高OMG水平，但这些发生在9和11天后，分别。这揭示了非触发引发机制，这对引发的贡献最大，并与基质矿化密切相关。通过将能量和底物依赖性代谢过程与触发过程分离，葡萄糖类似物3-O-甲基-d-葡萄糖使触发得以证明，但葡萄糖触发的发生对引发没有很大贡献。
Priming of soil organic matter decomposition has attracted much research interest, yet a conclusive mechanistic explanation of the phenomenon remains elusive. One proposal is that low molecular weight organic substances might “trigger” an acceleration of microbial metabolism. For the first time, we applied a glucose analogue to soil to demonstrate triggering of microbial metabolism, and to estimate its relative contribution to priming. “Non-metabolizable” glucose analogues have been widely used in pure culture studies to mimic glucose, but never in soil biochemistry. We hypothesized that analogue molecules will elicit a metabolic response in microorganisms despite limited catabolism, and thereby confirm the proposed triggering.The effect of14C-labeled 3-O-methyl-d-glucose (OMG) – a common “non-metabolizable” glucose analogue – on soil organic matter mineralization was compared to that of14C-labeledd-glucose. OMG was mineralized, but its mineralization was initially impeded and substantially delayed, relative to glucose. OMG caused brief but strong priming in the first 24 h, increasing unlabeled CO2efflux by 173%, 89% and 36% above control for additions of 0.49, 2.4 and 4.9 μmol OMG g−1soil, respectively. In contrast, glucose caused low or negative priming on the first day. On the first day after OMG addition, a negative correlation between priming and OMG mineralization indicated that triggering is a valid mechanism of microbial activation during a famine-feast transition, but is short-lived.Glucose mineralization peaked on the second day for medium and high additions, coinciding with peaks in positive priming. Maximum substrate mineralization also coincided with peaks in priming for medium and high OMG levels, but these occurred 9 and 11 days after addition, respectively. This revealed non-triggering priming mechanisms, which contributed most to priming and were closely coupled to substrate mineralization. By separating energy- and substrate-dependent metabolic processes from triggering processes, the glucose analogue 3-O-methyl-d-glucose enabled triggering to be demonstrated, but triggering by glucose occurs without contributing greatly to priming.