Ecoenzymatic stoichiometry of recalcitrant organic matter decomposition: the growth rate hypothesis in reverse
Ecoenzymatic stoichiometry of recalcitrant organic matter decomposition: the growth rate hypothesis in reverse
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DOI：
10.1007/s10533-010-9482-x
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发表时间：
2011-01-01
期刊：
影响因子：
4
通讯作者：
Shah, Jennifer J. Follstad
中科院分区：
文献类型：
--
作者：
Sinsabaugh, Robert L.;Shah, Jennifer J. Follstad
碳和营养物质从植物生产流入碎屑食物网是由释放到环境中的微生物酶（生态酶）介导的。生态酶活性与微生物代谢和环境资源可用性有关。在本文中，我们扩展了生态酶化学计量学的理论和经验框架，从养分的有效性，碳组成相关的β-1，4-葡萄糖苷酶（BG），酸性（碱性）磷酸酶（AP），β-N-乙酰氨基葡萄糖苷酶（NAG），亮氨酸氨肽酶（AKP）和酚氧化酶（POX）的活性在土壤中的比例，以衡量有机质的可吸收性，使用数据来自28个生态系统。BG和POX活性是不相关的，即使两者都是木质纤维素降解所需的。然而，BG：POX活性的比例与柠檬酸碳的相对丰度呈负相关。与BG不同，POX活性与（NAG + NAG）和AP活性正相关。本文提出，有机质胁迫对微生物C：N和C：P阈值元素比（TER）的影响可用BG、AP和（NAG + NAG）活性对POX活性的归一化来表示。这些比率之间的标度关系表明，增加分解有机物的增重有效地扭转了增长率假设的化学计量理论，减少碳和养分的可用性和减缓增长，这增加TERN：P。这种效果是一致的平均元素C：N比的土壤有机质和微生物生物量之间的差异很小，与N富集的抑制作用的分解和微生物代谢率为增重的有机物。从这些研究结果，我们提出了一个概念框架，自下而上的分解模型，整合到一般生态理论的ecoenzymatic活动的化学计量。
The flow of carbon and nutrients from plant production into detrital food webs is mediated by microbial enzymes released into the environment (ecoenzymes). Ecoenzymatic activities are linked to both microbial metabolism and environmental resource availability. In this paper, we extend the theoretical and empirical framework for ecoenzymatic stoichiometry from nutrient availability to carbon composition by relating ratios of beta-1,4-glucosidase (BG), acid (alkaline) phosphatase (AP), beta-N-acetylglucosaminidase (NAG), leucine aminopeptidase (LAP) and phenol oxidase (POX) activities in soils to measures of organic matter recalcitrance, using data from 28 ecosystems. BG and POX activities are uncorrelated even though both are required for lignocellulose degradation. However, the ratio of BG:POX activity is negatively correlated with the relative abundance of recalcitrant carbon. Unlike BG, POX activity is positively correlated with (NAG + LAP) and AP activities. We propose that the effect of organic matter recalcitrance on microbial C:N and C:P threshold element ratios (TER) can be represented by normalizing BG, AP and (NAG + LAP) activities to POX activity. The scaling relationships among these ratios indicate that the increasing recalcitrance of decomposing organic matter effectively reverses the growth rate hypothesis of stoichiometric theory by decreasing carbon and nutrient availability and slowing growth, which increases TERN:P. This effect is consistent with the narrow difference between the mean elemental C:N ratios of soil organic matter and microbial biomass and with the inhibitory effect of N enrichment on rates of decomposition and microbial metabolism for recalcitrant organic matter. From these findings, we propose a conceptual framework for bottom-up decomposition models that integrate the stoichiometry of ecoenzymatic activities into general theories of ecology.