Department of Environmental Science, Aarhus University, DK-4000 Roskilde, Denmark.
Department of Biology, University of Copenhagen, DK-2100 Copenhagen, Denmark.
Sci Rep. 2017 Feb 23;7:43338. doi: 10.1038/srep43338.
Drilling and handling of permanently frozen soil cores without microbial contamination is of concern because contamination e.g. from the active layer above may lead to incorrect interpretation of results in experiments investigating potential and actual microbial activity in these low microbial biomass environments. Here, we present an example of how microbial contamination from active layer soil affected analysis of the potentially active microbial community in permafrost soil. We also present the development and use of two tracers: (1) fluorescent plastic microspheres and (2) Pseudomonas putida genetically tagged with Green Fluorescent Protein production to mimic potential microbial contamination of two permafrost cores. A protocol with special emphasis on avoiding microbial contamination was developed and employed to examine how far microbial contamination can penetrate into permafrost cores. The quantity of tracer elements decreased with depth into the permafrost cores, but the tracers were detected as far as 17 mm from the surface of the cores. The results emphasize that caution should be taken to avoid microbial contamination of permafrost cores and that the application of tracers represents a useful tool to assess penetration of potential microbial contamination into permafrost cores.
在不引入微生物污染的情况下钻取和处理永久性冻土岩芯是一个需要关注的问题,因为来自上层活跃层的污染可能会导致在研究这些微生物生物量较低环境中潜在和实际微生物活性的实验中得出错误的结果。在这里,我们展示了一个例子,说明来自活跃层土壤的微生物污染如何影响对多年冻土土壤中潜在活性微生物群落的分析。我们还介绍了两种示踪剂的开发和使用:(1)荧光塑料微球和(2)带有绿色荧光蛋白产生的遗传标记的假单胞菌,以模拟对两个多年冻土岩芯的潜在微生物污染。制定并采用了一项特别强调避免微生物污染的方案,以检查微生物污染能渗透到多年冻土岩芯多远的距离。示踪元素的数量随着深入多年冻土岩芯而减少,但示踪剂在距离岩芯表面 17 毫米的地方仍被检测到。研究结果强调,应该小心避免多年冻土岩芯受到微生物污染,并且示踪剂的应用代表了评估潜在微生物污染渗透到多年冻土岩芯的有用工具。