Temperature sensitivity of soil enzyme kinetics under N‐fertilization in two temperate forests
Temperature sensitivity of soil enzyme kinetics under N‐fertilization in two temperate forests
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DOI：
10.1111/j.1365-2486.2011.02545.x
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发表时间：
2012-03
影响因子：
11.6
通讯作者：
M. Stone;M. Weiss;C. Goodale;M. Adams;I. Fernandez;D. German;S. Allison
中科院分区：
文献类型：
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作者：
M. Stone;M. Weiss;C. Goodale;M. Adams;I. Fernandez;D. German;S. Allison
土壤微生物产生胞外酶，降解土壤有机质中的含碳聚合物。由于胞外酶活性可能对增加的氮（N）和温度变化敏感，我们测量了长期N添加和短期温度变化对缅因州熊溪硬木林和西弗吉尼亚州费尔诺森林土壤酶动力学的影响。我们确定了五种水解酶的Vmax和Km参数：α-葡萄糖苷酶、β-葡萄糖苷酶、β-木糖苷酶、纤维二糖水解酶和N-乙酰氨基葡萄糖苷酶。Vmax和Km的温度敏感性进行了评估，在土壤样品进行了一系列的温度。我们假设（1）N添加会导致微生物C限制，导致较高的酶Vmax值和较低的Km值;（2）Vmax和Km在较高的温度下都会增加。最后，我们测试是否温度敏感性的酶动力学介导的N添加。氮添加显着或轻微显着增加Vmax值的所有酶，特别是在费尔诺。氮施肥导致显着降低Km值的所有酶在熊溪，但变量Km的反应在费尔诺森林。Vmax和Km都是温度敏感的，酶Vmax的Q10值范围为1.64-2.27，酶Km的Q10值范围为1.04-1.93。对于Vmax，没有酶显示出N和温度敏感性之间的显著相互作用，并且对于Km，只有β-木糖苷酶显示出N和温度敏感性之间的显著相互作用。我们的研究是第一个实验证明土壤酶Km和温度之间的正相关关系。Vmax相对于Km的较高温度敏感性意味着衬底退化将随温度而增加。此外，Vmax和Km对N的响应表明在N添加下更大的底物降解。我们的研究结果表明，在美国东北部的森林温度和氮的可用性增加将导致水解酶的活性增加，尽管积极的温度敏感性公里。
Soil microbes produce extracellular enzymes that degrade carbon (C)‐containing polymers in soil organic matter. Because extracellular enzyme activities may be sensitive to both increased nitrogen (N) and temperature change, we measured the effect of long‐term N addition and short‐term temperature variation on enzyme kinetics in soils from hardwood forests at Bear Brook, Maine, and Fernow Forest, West Virginia. We determined the Vmax and Km parameters for five hydrolytic enzymes: α‐glucosidase, β‐glucosidase, β‐xylosidase, cellobiohydrolase, and N‐acetyl‐glucosaminidase. Temperature sensitivities of Vmax and Km were assessed within soil samples subjected to a range of temperatures. We hypothesized that (1) N additions would cause microbial C limitation, leading to higher enzyme Vmax values and lower Km values; and (2) both Vmax and Km would increase at higher temperatures. Finally, we tested whether or not temperature sensitivity of enzyme kinetics is mediated by N addition. Nitrogen addition significantly or marginally significantly increased Vmax values for all enzymes, particularly at Fernow. Nitrogen fertilization led to significantly lower Km values for all enzymes at Bear Brook, but variable Km responses at Fernow Forest. Both Vmax and Km were temperature sensitive, with Q10 values ranging from 1.64–2.27 for enzyme Vmax and 1.04–1.93 for enzyme Km. No enzyme showed a significant interaction between N and temperature sensitivity for Vmax, and only β‐xylosidase showed a significant interaction between N and temperature sensitivity for Km. Our study is the first to experimentally demonstrate a positive relationship between Km and temperature for soil enzymes. Higher temperature sensitivities for Vmax relative to Km imply that substrate degradation will increase with temperature. In addition, the Vmax and Km responses to N indicate greater substrate degradation under N addition. Our results suggest that increasing temperatures and N availability in forests of the northeastern US will lead to increased hydrolytic enzyme activity, despite the positive temperature sensitivity of Km.