Biochemistry of hexose and pentose transformations in soil analyzed by position-specific labeling and 13C-PLFA
Biochemistry of hexose and pentose transformations in soil analyzed by position-specific labeling and 13C-PLFA
复制标题
DOI：
10.1016/j.soilbio.2014.09.005
复制
发表时间：
2015-01-01
影响因子：
9.7
通讯作者：
Kuzyakov, Yakov
中科院分区：
文献类型：
--
作者：
Apostel, Carolin;Dippold, Michaela;Kuzyakov, Yakov
微生物转化是土壤有机质形成、稳定和分解的关键过程。位置特异性C-13标记与化合物特异性C-13- plfa分析相结合是一种追踪代谢途径的新工具。该组合用于分析田间条件下土壤中两种关键单糖：葡萄糖和核糖的短期转化（施用示踪剂后3天和10天）。糖的转化通过C-13在土壤、微生物生物量（通过CFE）和按C-13- plfa分类的微生物群细胞膜中的单个分子位置的结合来量化。革兰氏阴性菌中C-13的掺入比所有其他微生物群高一个数量级。第3天土壤中回收的C-13全部分配在微生物生物量中。然而，在第10天，部分C-13在不可提取的微生物细胞成分或微生物排泄物中被回收。由于缺乏带电荷的官能团，糖不能被矿物颗粒吸收，因此一般认为糖可以从土壤溶液中快速矿化。然而，微生物将糖转化为代谢物的速度较慢。C-13从单个葡萄糖位置进入土壤和微生物生物量表明，生物体内的糖酵解和戊糖磷酸两种主要葡萄糖利用途径在土壤中平行存在。然而，C-13从单个葡萄糖位置结合到PLFAs的模式表明，通过糖异生和两种葡萄糖利用途径的混合，增加的C-13进行了密集的再循环。核糖C的位置特异性结合模式也显示了戊糖磷酸途径的初始利用，但在第10天再次由于密集的循环和混合而重叠。这表明葡萄糖和核糖作为普遍存在的底物，在各种代谢途径中被使用，它们的C在微生物生物量中被密集地循环利用。通过位置特异性标记分析单个C原子的命运，极大地提高了我们对微生物群利用糖（和其他化合物）的途径以及土壤C通量的理解。(C) 2014 Elsevier Ltd.版权所有。
Microbial transformations are key processes of soil organic matter (SOM) formation, stabilization and decomposition. Combination of position-specific C-13 labeling with compound-specific C-13-PLFA analysis is a novel tool to trace metabolic pathways. This combination was used to analyze short-term transformations (3 and 10 days after tracer application) of two key monosaccharides: glucose and ribose in soil under field conditions. Transformations of sugars were quantified by the incorporation of C-13 from individual molecule positions in bulk soil, microbial biomass (by CFE) and in cell membranes of microbial groups classified by C-13-PLFA.The C-13 incorporation in the Gram negative bacteria was higher by one order of magnitude compared to all other microbial groups. All of the C-13 recovered in soil on day 3 was allocated in microbial biomass. On day 10 however, a part of the C-13 was recovered in non-extractable microbial cell components or microbial excretions. As sugars are not absorbed by mineral particles due to a lack of charged functional groups, their quick mineralization from soil solution is generally expected. However, microorganisms transformed sugars to metabolites with a slower turnover. The C-13 incorporation from the individual glucose positions into soil and microbial biomass showed that the two main glucose utilizing pathways in organisms - glycolysis and the pentose phosphate pathway - exist in soils in parallel. However, the pattern of C-13 incorporation from individual glucose positions into PLFAs showed intensive recycling of the added C-13 via gluconeogenesis and a mixing of both glucose utilizing pathways. The pattern of position-specific incorporation of ribose C also shows initial utilization in the pentose phosphate pathway but is overprinted on day 10, again due to intensive recycling and mixing. This shows that glucose and ribose - as ubiquitous substrates - are used in various metabolic pathways and their C is intensively recycled in microbial biomass.Analyzing the fate of individual C atoms by position-specific labeling deeply improves our understanding of the pathways of microbial utilization of sugars (and other compounds) by microbial groups and so, of soil C fluxes. (C) 2014 Elsevier Ltd. All rights reserved.