Role of substrate supply on microbial carbon use efficiency and its role in interpreting soil microbial community-level physiological profiles (CLPP)
Role of substrate supply on microbial carbon use efficiency and its role in interpreting soil microbial community-level physiological profiles (CLPP)
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DOI：
10.1016/j.soilbio.2018.04.014
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发表时间：
2018-08-01
影响因子：
9.7
通讯作者：
Murphy, D. V.
中科院分区：
文献类型：
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作者：
Jones, D. L.;Hill, P. W.;Murphy, D. V.
碳利用效率（CUE）描述了土壤微生物群落内合成代谢和分解代谢过程之间碳（C）的相对分配。此外，它是调节通过土壤食物网营养级级联的碳量的主要因素。然而，CUE 与 C 供应的关系仍然知之甚少。本研究的主要目的是确定 CUE 如何在一系列空间尺度上随着 C 底物供应的变化而变化。我们的次要目标是了解底物 CUE 的变化如何影响群落水平生理特征 (CLPP) 的解释。我们使用 16 种不同的 C-14 标记底物（包括氨基酸、糖、有机酸和氨基糖）以及在田间、区域和大陆范围内收集的土壤，测量了底物吸收和矿化的速率，并据此计算了 CUE。在所有土壤 (n = 114) 和基质 (n = 16) 中，微生物群落的平均 CUE 为 0.568 +/- 0.004（范围 0.492-0.794）。虽然 72 小时内底物 C 在生物质中的分配（固定/矿化）对于某些底物（例如葡萄糖）而言是高度保守的，但其他底物在整个样品（例如缬氨酸）中的 CUE 表现出很大的变异性。在 CLPP 方法的背景下，我们表明，无论统计分析是基于微生物底物吸收率还是矿化率，各个位点都可以在统计上彼此分离。然而，我们的结果确实表明，由于基质之间的 CUE 存在很大差异，因此在将观察到的 CLPP 差异归因于土壤中运行的单个 C 途径的重要性时需要谨慎。总之，我们提出了新的机制证据来支持这一范式，即生态系统 CUE 的变化可能部分反映了提供给微生物生物量的 C 类型的差异。
Carbon use efficiency (CUE) describes the relative partitioning of carbon (C) between anabolic and catabolic processes within the soil microbial community. Further, it represents a major factor regulating the amount of C cascading through the trophic levels of the soil food web. How CUE relates to C supply, however, remains poorly understood. The primary aim of this study was to determine how CUE varies across a range of spatial scales as a function of C substrate supply. Our secondary aim was to understand how variations in substrate CUE influences the interpretation of community level physiological profiles (CLPP). Using 16 different C-14-labelled substrates (including amino acids, sugars, organic acids and amino sugars) and soils collected at the field, regional and continental scale, we measured the rate of substrate uptake and mineralization from which we calculated CUE. Across all soils (n = 114) and substrates (n = 16), the average CUE for the microbial community was 0.568 +/- 0.004 (range 0.492-0.794). While the partitioning of substrate-C within the biomass (immobilization/mineralization) over 72 h was highly conserved for some substrates (e.g. glucose), others showed a wide variability in CUE across the samples (e.g. valine). In the context of the CLPP methodology, we showed that individual sites could be statistically separated from each other, irrespective of whether the statistical analysis was based on microbial substrate uptake rate or mineralization rate. However, our results do suggest that caution is needed when ascribing observed CLPP differences to the importance of individual C pathways operating in soil due to the wide variation of CUE between substrates. In conclusion, we present new mechanistic evidence to support the paradigm that variation in ecosystem CUE may in part reflect differences in the types of C supplied to the microbial biomass.