A litter-slurry technique elucidates the key role of enzyme production and microbial dynamics in temperature sensitivity of organic matter decomposition
A litter-slurry technique elucidates the key role of enzyme production and microbial dynamics in temperature sensitivity of organic matter decomposition
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DOI：
10.1016/j.soilbio.2011.12.009
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发表时间：
2012-04
影响因子：
9.7
通讯作者：
M. Wallenstein;M. Haddix;D. D. Lee-D.;R. Conant;E. Paul
中科院分区：
文献类型：
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作者：
M. Wallenstein;M. Haddix;D. D. Lee-D.;R. Conant;E. Paul
有机物分解的速度通常随着温度的升高而增加，除非它受到物理化学保护而不受酶解聚的影响。分解的温度敏感性应随反应速率的降低而增加，对应于分解化合物的活化能的增加。检验这种碳质量温度假设的一种方法是研究温度对凋落叶分解的影响，因为新鲜的地表凋落叶是不受保护的。然而，其他因素如湿度随温度共同变化，生物过程如酶的产生和微生物种群的生长也可能是热敏的。我们开发了一种凋落物浆法来分离温度和凋落物质量对分解的影响。研究发现，松木凋落物分解速度快于栎树凋落物，与C:N和木质素：N比较低一致。在分解的前14天，25°C和35°C孵育的凋落物的分解速率没有差异。35°C时潜在的酶活性较低，表明35°C时酶的产生比25°C时受到抑制，导致两种温度下的原位酶活性相似。14天后，两种孵育温度下的酶池相似，这导致温度越高，分解速度越快，符合酶动力学理论。在第14天，优质松木凋落物的分解速率比劣质栎树凋落物的分解速率对温度更敏感，说明这一阶段的温度敏感性是由可溶性池的质量而非体积化学决定的。28 d后，栎树凋落物分解比松木凋落物对温度更敏感，符合碳温度-质量假设。研究表明，生物对温度的响应会影响分解的表观温度敏感性，因此需要进一步研究微生物对温度的响应。
The rate at which organic matter decomposes generally increases with temperature, unless it is physico-chemically protected from enzymatic depolymerization. The temperature sensitivity of decomposition should increase with decreasing reaction rates, corresponding to increasing activation energy of the decomposing compounds. One approach to testing this carbon-quality temperature hypothesis is to study the effect of temperature on leaf litter decomposition, because fresh surface litter is unprotected. However, other factors such as humidity co-vary with temperature, and biological processes such as enzyme production and microbial population growth may also be thermally sensitive. We developed a litter slurry approach to isolate the effect of temperature and litter quality on decomposition. We found that pine litter decomposed faster than oak litter, consistent with a lower C:N and lignin:N ratio. During the first 14 days of decomposition, there was no difference in decomposition rate for litter incubated at 25 °C compared to 35 °C. Lower potential enzyme activity at 35 °C suggested that enzyme production was suppressed at 35 °C compared to 25 °C, resulting in similar in situ enzyme activities at the two temperatures. After 14 days, enzyme pools were similar between the two incubation temperatures, which resulted in faster decomposition at the warmer temperature, consistent with enzyme kinetic theory. At Day 14, the decomposition rate of the high quality pine litter was more temperature sensitive than the decomposition rate of the lower quality oak litter, suggesting that the quality of soluble pool rather than bulk chemistry determined the temperature sensitivity during this stage. After 28 days of incubation, oak litter decomposition was more temperature sensitive than pine litter, consistent with the carbon temperature-quality hypothesis. The litter slurry approach revealed that biological responses to temperature can affect the apparent temperature sensitivity of decomposition, and highlight a need for further research into microbial responses to temperature.