title: Potential microbial contamination during sampling of permafrost soil assessed by tracers.
abstract: 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.
authors.affiliation: Department of Environmental Science, Aarhus University, DK-4000 Roskilde, Denmark.|Department of Biology, University of Copenhagen, DK-2100 Copenhagen, Denmark.|Center for Permafrost (CENPERM), Department of Geosciences and Natural Resource Management, University of Copenhagen, DK-1350 Copenhagen, Denmark.
authors.forename: Toke
authors.initials: T
authors.lastname: Bang-Andreasen
authors.affiliation: Department of Biology, University of Copenhagen, DK-2100 Copenhagen, Denmark.|Center for Permafrost (CENPERM), Department of Geosciences and Natural Resource Management, University of Copenhagen, DK-1350 Copenhagen, Denmark.
authors.forename: Morten
authors.initials: M
authors.lastname: Schostag
authors.affiliation: Department of Biology, University of Copenhagen, DK-2100 Copenhagen, Denmark.|Center for Permafrost (CENPERM), Department of Geosciences and Natural Resource Management, University of Copenhagen, DK-1350 Copenhagen, Denmark.
authors.forename: Anders
authors.initials: A
authors.lastname: Priemé
authors.affiliation: Center for Permafrost (CENPERM), Department of Geosciences and Natural Resource Management, University of Copenhagen, DK-1350 Copenhagen, Denmark.
authors.forename: Bo
authors.initials: B
authors.lastname: Elberling
authors.affiliation: Department of Environmental Science, Aarhus University, DK-4000 Roskilde, Denmark.|Center for Permafrost (CENPERM), Department of Geosciences and Natural Resource Management, University of Copenhagen, DK-1350 Copenhagen, Denmark.
authors.forename: Carsten S
authors.initials: CS
authors.lastname: Jacobsen
mesh_terms: D058448:Biota; D003951:Diagnostic Errors; D008828:Microbiological Techniques / Q000379:methods*; D065946:Permafrost / Q000382:microbiology*