Conclusion

Both culture-dependent and culture-independent methods have revealed that permafrost harbors diverse and novel microbial communities. The future challenge for the study of permafrost microbiology is to begin to address the ecology of these unique microbial ecosystems. The knowledge gained from culture-independent surveys of microbial diversity can be used to design targeted culturing strategies in order to determine if phylogenetic groups detected by molecular strategies are part of the viable microbial community. Moreover, the characterization of the microbial component of permafrost will provide important insights into how these environments will respond to climate change in regard to the increased metabolic rates associated with higher temperatures and nutrient availability due to the melting of permafrost. The application of technologies such as stable isotope probing (Dumont et al. 2006) and FISH-microautoradiography (Lee et al. 1999) could identify active microorganisms, and better define the functioning and maintenance of permafrost microbial ecosystems at ambient subzero temperatures. As microbial activities in situ are expected to be extremely slow and minute, new methods and technologies specific to the permafrost environment will be required. For example, we have recently described a method to measure microbial respiration at subzero temperatures that was effective at detecting low amounts of microbial respiration occurring at temperatures as low as -15°C from a variety of Arctic environments (Steven et al. 2007b). Developing methods to detect and characterize the active Bacteria and Archaea in permafrost will allow for the differentiation of the active microbial populations presumed to exist in permafrost from cryopreserved microbial fossils that may have remained frozen for geological time scales.

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