Enzymatic activities and microbial communities in an Antarctic dry valley soil: Responses to C and N supplementation
Enzymatic activities and microbial communities in an Antarctic dry valley soil: Responses to C and N supplementation
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DOI：
10.1016/j.soilbio.2008.03.022
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发表时间：
2008-09
影响因子：
9.7
通讯作者：
D. Hopkins;A. Sparrow;L. Shillam;L. English;P. Dennis;P. Novis;B. Elberling;E. Gregorich;L. Greenfield
中科院分区：
文献类型：
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作者：
D. Hopkins;A. Sparrow;L. Shillam;L. English;P. Dennis;P. Novis;B. Elberling;E. Gregorich;L. Greenfield
南极干旱山谷的土壤暴露在极其干燥和寒冷的条件下。然而，它们含有小型微生物群落，有助于生物元素的生物地球化学转化，尽管速度较慢。我们通过对南极干旱山谷现场实验收集的土壤进行实验室分析，确定了脱氢酶、β-葡萄糖苷酶、酸性和碱性磷酸酶以及芳基硫酸酯酶的活性以及呼吸速率（二氧化碳产生量）。现场实验的目的是测试土壤微生物群落对添加简单形式（葡萄糖和 NH4Cl）和复杂形式（来自邻近湖泊的甘氨酸和湖泊碎屑，主要包括蓝细菌坏死物）的 C 和 N 的反应。土壤样本是在实验处理实施后三年采集的。在未改良的土壤中，检测到所有酶活性和呼吸作用，表明土壤中存在矿化有机 C、P 和 S 化合物的酶能力，尽管有机质含量非常低。相对于对照（未改良的土壤），除最小的 NH4Cl 添加量（1mg N g−1soil）和最小的碎屑添加量（1.5mg C g−1soil 和 0.13mg N g−1soil）外，所有实验添加的 C 和 N 均显着增加了呼吸作用。除脱氢酶外，所有酶的活性均因C和大量C（10mg C g−1soil）和N的添加而增加，但通过仅添加N或仅添加N（高达10mg N g−1soil）和仅以葡萄糖和NH4Cl形式添加少量C（1mg C g−1soil）而没有变化或减弱。这表明在存在大量氮的情况下，酶生物合成的碳供应是有限的。当对土壤呼吸进行标准化时，只有每单位呼吸的芳基硫酸酯酶显示出随着葡萄糖和NH4Cl等C和N的添加而显着增加，这与当C和N限制得到缓解时的S限制一致。基于酶活性的积极反应，碎屑似乎提供了比以特定化合物（葡萄糖、NH4Cl 或甘氨酸）形式添加的类似量的 C 和更多的 N 产生更大的生物反应的条件或资源。通过酯连接脂肪酸 (ELFA) 分析对土壤微生物群落进行评估，没有发现碳和氮补充处理导致群落结构发生变化的证据。因此，呼吸和酶活性对补充的反应发生在结构明显稳定或无反应的微生物群落中。
The soils of the Antarctic dry valleys are exposed to extremely dry and cold conditions. Nevertheless, they contain small communities of micro-organisms that contribute to the biogeochemical transformations of the bioelements, albeit at slow rates. We have determined the dehydrogenase, β-glucosidase, acid and alkaline phosphatase and arylsulphatase activities and the rates of respiration (CO2production) in laboratory assays of soils collected from a field experiment in an Antarctic dry valley. The objective of the field experiment was to test the responses of the soil microbial community to additions of C and N in simple (glucose and NH4Cl) and complex forms (glycine and lacustrine detritus from the adjacent lake comprising principally cyanobacterial necromass). The soil samples were taken 3years after the experimental treatments had been applied. In unamended soil, all enzyme activities and respiration were detected indicating that the enzymatic capacity to mineralize organic C, P and S compounds existed in the soil, despite the very low organic matter content. Relative to the control (unamended soil), respiration was significantly increased by all the experimental additions of C and N except the smallest NH4Cl addition (1mg N g−1soil) and the smallest detritus addition (1.5mg C g−1soil and 0.13mg N g−1soil). The activities of all enzymes except dehydrogenase were increased by C and combined large C (10mg C g−1soil) and N additions, but either unchanged or diminished by addition of either N only or N (up to 10mg N g−1soil) with only small C (1mg C g−1soil) additions in the form of glucose and NH4Cl. This suggests that in the presence of a large amount of N, the C supply for enzyme biosynthesis was limited. When normalized with respect to soil respiration, only arylsulphatase per unit of respiration showed a significant increase with C and N additions as glucose and NH4Cl, consistent with S limitation when C and N limitations have been alleviated. Based on the positive responses of enzyme activity, detritus appeared to provide either conditions or resources which led to a larger biological response than a similar amount of C and more N added in the form of defined compounds (glucose, NH4Cl or glycine). Assessment of the soil microbial community by ester-linked fatty acid (ELFA) analysis provided no evidence of changes in the community structure as a result of the C and N supplementation treatments. Thus the respiration and enzyme activity responses to supplementation occurred in an apparently structurally stable or unresponsive microbial community.