Norris Tracy B, Wraith Jon M, Castenholz Richard W, McDermott Timothy R
Thermal Biology Institute and Department of Land Resources and Environmental Sciences, Montana State University, Bozeman 59717, USA.
Appl Environ Microbiol. 2002 Dec;68(12):6300-9. doi: 10.1128/AEM.68.12.6300-6309.2002.
In this study microbial species diversity was assessed across a landscape in Yellowstone National Park, where an abrupt increase in soil temperature had occurred due to recent geothermal activity. Soil temperatures were measured, and samples were taken across a temperature gradient (35 to 65 degrees C at a 15-cm depth) that spanned geothermally disturbed and unimpacted soils; thermally perturbed soils were visually apparent by the occurrence of dead or dying lodgepole pine trees. Changes in soil microbial diversity across the temperature gradient were qualitatively assessed based on 16S rRNA sequence variation as detected by denaturing gradient gel electrophoresis (DGGE) using both ribosomal DNA (rDNA) and rRNA as PCR templates and primers specific for the Bacteria or Archaea domain. The impact of the major heating disturbance was apparent in that DGGE profiles from heated soils appeared less complex than those from the unaffected soils. Phylogenetic analysis of a bacterial 16S rDNA PCR clone library from a recently heated soil showed that a majority of the clones belonged to the Acidobacterium (51%) and Planctomyces (18%) divisions. Agar plate counts of soil suspensions cultured on dilute yeast extract and R2A agar media incubated at 25 or 50 degrees C revealed that thermophile populations were two to three orders of magnitude greater in the recently heated soil. A soil microcosm laboratory experiment simulated the geothermal heating event. As determined by both RNA- and DNA-based PCR coupled with DGGE, changes in community structure (marked change in the DGGE profile) of soils incubated at 50 degrees C occurred within 1 week and appeared to stabilize after 3 weeks. The results of our molecular and culture data suggest that thermophiles or thermotolerant species are randomly distributed in this area within Yellowstone National Park and that localized thermal activity selects for them.
在本研究中，我们评估了黄石国家公园一个区域内的微生物物种多样性，该区域因近期的地热活动导致土壤温度急剧升高。我们测量了土壤温度，并在一个温度梯度（15厘米深度处为35至65摄氏度）上采集样本，该温度梯度涵盖了受地热干扰和未受影响的土壤；受热扰动的土壤通过死树或濒死的黑松林的出现而在视觉上明显可见。基于变性梯度凝胶电泳（DGGE）检测到的16S rRNA序列变异，以核糖体DNA（rDNA）和rRNA作为PCR模板以及针对细菌或古菌域的特异性引物，定性评估了温度梯度上土壤微生物多样性的变化。主要加热干扰的影响很明显，因为来自受热土壤的DGGE图谱比未受影响土壤的图谱显得更不复杂。对来自最近受热土壤的细菌16S rDNA PCR克隆文库进行系统发育分析表明，大多数克隆属于嗜酸菌门（51%）和浮霉菌门（18%）。在25或50摄氏度下培养在稀释酵母提取物和R2A琼脂培养基上的土壤悬浮液的琼脂平板计数显示，最近受热土壤中的嗜热菌种群数量比未受热土壤中的高两到三个数量级。一项土壤微观世界实验室实验模拟了地热加热事件。通过基于RNA和DNA的PCR结合DGGE测定，在50摄氏度下培养的土壤群落结构变化（DGGE图谱有明显变化）在1周内发生，并在3周后似乎趋于稳定。我们的分子和培养数据结果表明，嗜热菌或耐热物种在黄石国家公园的这个区域内随机分布，局部热活动对它们进行了选择。
