Sorption of Alanine changes microbial metabolism in addition to availability
Sorption of Alanine changes microbial metabolism in addition to availability
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DOI：
10.1016/j.geoderma.2017.01.016
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发表时间：
2017-04-15
期刊：
影响因子：
6.1
通讯作者：
Kuzyakov, Yakov
中科院分区：
文献类型：
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作者：
Apostel, Carolin;Dippold, Michaela A.;Kuzyakov, Yakov
吸附作用是土壤中有机质抵抗微生物矿化的主要过程之一。我们推测，除了减少微生物和酶的可及性，微生物代谢的变化还加强了这种有机物的吸附稳定作用。将位置特异性C-14标记的丙氨酸以溶液形式施加到土壤中或吸附在灭菌土壤上，以研究这种代谢相关的稳定作用的机制。吸附作用使丙氨酸的初始矿化降低了约80%，并使矿化最大值（（CO2）-C-14峰）的持续时间增加了一倍。几乎所有的丙氨酸都被微生物吸收，不依赖于吸附，并且C-1在一天后的糖酵解过程中完全（>99%）脱羧。吸附不能阻止微生物利用丙氨酸，但增加了60%的吸附丙氨酸的碳利用效率（CUE）相比，在溶液中的丙氨酸，并增加了微生物生物量中的C掺入高达四倍。C-14在土壤和微生物生物量中的位置特异性模式表明，与游离丙氨酸相比，吸附丙氨酸中C-2的氧化强烈降低。更高的CUE和延迟的C-2矿化是通过更高的C通量实现的有效的anadministration，或/和较慢的循环细胞components.Limitation的可及性微生物单独不能解释的稳定效果的吸附对有机物质，如氨基酸和所观察到的变化的位置特定的模式。即使所有吸附的丙氨酸在3天内被微生物吸收，C分配向厌氧微生物，较慢的微生物周转和增加CUE增加C保留从吸附的化合物在土壤中，即使在微生物吸收。位置特异性标记清楚地表明，LMWOS通过吸附而不是作为完整的分子稳定，而是在微生物代谢后-作为释放的代谢物或微生物生物量。我们得出的结论是，吸附的间接效应，即1）更多的C分配到土壤中，2）较慢的分解，3）更高的掺入到微生物生物量和4）增加碳利用效率促进C保留在土壤中，可能比直接效应，即不可及性更重要。这一发现，稳定并没有显着阻碍微生物的利用，但吸附大大提高了碳的利用效率有重大影响的概念和数值表示有机质的稳定和土壤中的损失。(C)2017爱思唯尔B. V.保留所有权利。
Sorption is one of the main processes stabilizing organic matter in soil against microbial mineralization. We hypothesize that besides reduced accessibility for microorganisms and enzymes, changes in microbial metabolism additionally intensify this organic matter stabilization effect of sorption. Position-specifically C-14 labeled Alanine was applied to soil as solution or sorbed on sterilized soil to investigate the mechanisms underlying this metabolism related stabilization effect. Sorption decreased initial mineralization of Alanine by-80% and doubled the duration until the mineralization maxima ((CO2)-C-14 peak). Almost all Alanine was taken up by microorganisms independent on sorption, and C-1 was completely (>99%) decarboxylated during glycolysis after one day. Sorption could not prevent microbial utilization of Alanine, but increased the carbon use efficiency (CUE) of sorbed Alanine for 60% compared to Alanine in solution and increased C incorporation in microbial biomass up to four times. The position-specific pattern of C-14 in soil and in microbial biomass showed that oxidation of C-2 from sorbed Alanine was strongly lowered compared to free Alanine. Both higher CUE and delayed C-2 mineralization were achieved by a higher C flux towards efficient anabolism, or/and to slower cycling cell components.Limitation of accessibility for microorganisms alone does not explain the stabilizing effect of sorption on organic substances like amino acids and the observed changed position specific pattern. Even though all sorbed Alanine was taken up by microorganisms within 3 days, C partitioning towards anabolism, slower microbial turnover and increased CUE increased C retention from sorbed compounds in soil even after microbial uptake. Position-specific labeling clearly showed that LMWOS are stabilized by sorption not as intact molecules, but after microbial metabolization- as released metabolites or microbial biomass. We conclude that the indirect effects of sorption, namely 1) more C partitioned to anabolism, 2) slower decomposition, 3) higher incorporation into microbial biomass and 4) increased carbon use efficiency promote C retention in soil and may be even more important than the direct effect, namely inaccessibility. The finding that stabilization did not significantly impede microbial utilization, but sorption greatly increased carbon use efficiency has major implications for conceptual and numerical representation of organic matter stabilization and losses in soils. (C) 2017 Elsevier B.V. All rights reserved.