The pH optimum of soil exoenzymes adapt to long term changes in soil pH
The pH optimum of soil exoenzymes adapt to long term changes in soil pH
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DOI：
10.1016/j.soilbio.2019.107601
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发表时间：
2019-11
影响因子：
9.7
通讯作者：
J. Puissant;Briony A. Jones;T. Goodall;D. Mang;A. Blaud;H. Gweon;A. Malik;Davey L. Jones;
中科院分区：
文献类型：
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作者：
J. Puissant;Briony A. Jones;T. Goodall;D. Mang;A. Blaud;H. Gweon;A. Malik;Davey L. Jones;
微生物释放的土壤外源酶分解有机质，在调节C、N、P循环中起着至关重要的作用。已知土壤pH影响酶活性，也是微生物群落组成的强大驱动力；但关于土壤pH的变化如何影响酶活性以及这是如何由微生物群落调节的，人们知之甚少。为了评估酶对土壤pH的长期适应性，我们在Rothamsted Park Grass长期实验中保持在pH 5或7的两个历史管理土壤上进行了缓冲pH水平下的酶测定。参与C、N、P循环的一系列胞外酶的最适pH值在两种土壤中不同，其变化的方向是向源土壤的pH方向移动，表明土壤微生物群落产生了与pH相适应的同工酶。通过扩增序列测定，土壤细菌和真菌群落在pH 5和土壤pH 7之间明显不同，这可能解释了酶反应的差异。此外，从后基因组中提取的β-葡萄糖苷酶基因序列显示，在pH为5的土壤中，酸性细菌产生菌的丰度增加，在pH为7的土壤中，放线菌的数量增加。我们的发现表明，土壤外源酶的最适pH适应土壤pH的长期变化，其方向取决于土壤pH的变化；我们提供了进一步的证据，证明功能微生物群落的变化可能支持这一现象，尽管现在需要新的研究将酶活性最适变化与微生物群落直接联系起来。更广泛地说，我们的新发现对于在不断变化的环境条件下模拟不同微生物酶过程的效率具有重大意义。
Soil exoenzymes released by microorganisms break down organic matter and are crucial in regulating C, N and P cycling. Soil pH is known to influence enzyme activity, and is also a strong driver of microbial community composition; but little is known about how alterations in soil pH affect enzymatic activity and how this is mediated by microbial communities. To assess long term enzymatic adaptation to soil pH, we conducted enzyme assays at buffered pH levels on two historically managed soils maintained at either pH 5 or 7 from the Rothamsted Park Grass Long-term experiment. The pH optima for a range of exoenzymes involved in C, N, P cycling, differed between the two soils, the direction of the shift being toward the source soil pH, indicating the production of pH adapted isoenzymes by the soil microbial community. Soil bacterial and fungal communities determined by amplicon sequencing were clearly distinct between pH 5 and soil pH 7 soils, possibly explaining differences in enzymatic responses. Furthermore, β-glucosidase gene sequences extracted from metagenomes revealed an increased abundance of Acidobacterial producers in the pH 5 soils, and Actinobacteria in pH 7 soils. Our findings demonstrate that the pH optimum of soil exoenzymes adapt to long term changes in soil pH, the direction being dependent on the soil pH shift; and we provide further evidence that changes in functional microbial communities may underpin this phenomena, though new research is now needed to directly link change in enzyme activity optima with microbial communities. More generally, our new findings have large implications for modelling the efficiency of different microbial enzymatic processes under changing environmental conditions.