About Karen Junge Currently, my research interests lie at the interface of the biosphere and geosphere where I explore bacterial life at extremely low temperatures in ice. I am motivated by research questions that center around how polar psychrophilic (cold-loving) bacteria adapt to life in ice and how they interact with and impact their physical and chemical environment, questions that currently comprise a very active research field. To this end, I develop and use molecular biology, microbiology, geophysics and atmospheric science techniques. I am also interested in the genomic makeup of these organisms and molecular adaptations to the cold life style and how physiology, diversity and ecology of psychrophilic bacteria change when confronted with the extreme cold. I am driven to develop ways to analyze microbial communities under in-situ conditions with minimal disturbance of their natural environment. Curriculum Vitae (pdf)

Research Projects

1. By developing new microscopy and imaging techniques that allowed for the investigation of sea-ice bacteria within ice without melting it, I demonstrated in my PhD research (in collaboration with Jody Deming and Hajo Eicken) that surface associations to ice walls or particles within sea ice are essential for maintenance of activity to –20°C and that psychrophilic bacteria can still be motile to temperatures as low as –10°C moving at similar speeds as Escherichia coli at 37°C.

• Junge et al., 2001
• Junge et al., 2002
• Junge et al., 2003
• Junge et al., 2004

2. In this research project we examine the role that bacteria could play in polar atmospheric cloud formation and precipitation processes (on the general topic of bacteria in the atmosphere see: Biological Ice Nucleators.
   As Co-PI with Brian Swanson from the Lauck Foundation (NSF- OPP grant 0338333), we investigate if polar bacteria can interact with ice surfaces via ice nucleation processes. We know that heterotrophic bacteria play a key role in carbon cycling in polar regions, but we know only little about how they interact with their geological material, the ice itself, be it sea-ice, lake ice, glacier ice or ice in the atmosphere. The climate of the earth is very sensitive to the microphysical, radiative and chemical properties of glaciated clouds (IPCC, 2001). Accurate climate modeling requires that the entire process from particle formation to cloud drop nucleation be known. Studies of Arctic ice forming nuclei (IFN) have concluded that marine bacteria and other particles of biological origin derived from open leads within the sea-ice cover could be important for cloud formation in the Arctic (Bigg and Leck, 2002), but no investigations have been done on the ice-nucleating behavior of marine bacteria temporarily enclosed in sea ice. In Antarctica, devoid of a terrestrial source for IFN, studies also suggest that biological nuclei play a role in the formation of coastal clouds and that the surrounding ocean might be their source (Saxena, 1983). In my project with Brian, we investigate a likely origin of these biological nuclei - marine psychrophilic bacteria and viruses using a novel freeze tube technique that studies the freezing of droplets in free-fall.

• Laucks et al., 2005
• Junge and Swanson, 2008

3. Life as we know it requires liquid water. However we found evidence of ice bacterial protein synthesis to liquid nitrogen temperature (–196°C) when bacterial polymers were present and samples were (likely) vitrified during my postdoc (with Jody Deming and Hajo Eicken) and continuing on with Brian Swanson (supported by NSF-OPP grant 0338333; see New Scientist article).
   Currently, I am exploring the relationship between this deep-freeze bacterial activity, genomics, polymers and the physical state of the ice in collaboration with Barbara Methe at The Institute for Genomic Research (TIGR, http://www.tigr.org/) and Hajo Eicken at UAF (recently funded by NSF-OPP grant 0739783). This collaboration puts us in a unique position to solve an incredible puzzle (i.e. if and how can life be active without liquid water being present) and will provide important keys to questions regarding life under extreme conditions, be it in the atmosphere or elsewhere in the universe.

• Junge et al., 2006

4. Bacterial activity in glacier ice could also influence carbon dioxide levels and therefore possibly skew paleo-climatic records as suggested by Tung et al. (2006). To explore other ice formations such as glaciers I have recently submitted a proposal to study the hitherto unexamined chemistry and microbiology of meltwaters formed by the Greenland Ice sheet (in collaboration with Birgit Hagedorn (UAA), Ron Sletten (ESS) and Brent Christner (at LSU), an expert in the emerging field of glacial microbiology). All of these various research projects furthermore provide support for the possibility of continued bacterial activity during Snowball Earth events.





5. The field of Astrobiology represents a natural step to expand my curiosity about microbial life beyond Earth to extraterrestrial possible habitats for life allowing me to look at my research with a different perspective. Ice is ubiquitous in the Universe. If we better understand how microbial life adapts to Earth ice matrices, we will be in a better position to evaluate and plan tests of the habitability of frozen systems elsewhere in the Universe. In that way, it provides a new and to me very exciting context for my work: can we find life on other planets? Where will we have the best chances of detecting it? And how can we detect it? It motivates me to think that my research helps to address such questions that I consider fundamental to humanity. Thus, as part of our work in this field we contributed scientific input and images for NASA’s Astrobiology outreach website ‘Astroventure’ designed for 5 to 8 graders.

   
   

   Publications

   
   

   Junge, K., and B.D. Swanson. “High-resolution ice nucleation spectra of sea-ice bacteria: Implications for cloud formation and life in frozen environments”. Biogeosciences Discussion, 5, 865-873, 2008.

   
   

   T. Mock and K. Junge. “Psychrophilic Diatoms: Mechanisms for Survival in Freeze-thaw cycles. Algae and Cyanobacteria in Extreme Enviornments”. Biogeosciences Discussion, Ed. J. Seckback (Springer Verlag), pp. 343-364, 2007.

   
   

   K. Junge, H. Eicken, B. D. Swanson and, J. W. Deming. Bacterial incorporation of leucine into protein down to –20°C with evidence for potential activity in subeutectic saline ice formations. Cryobiol. 52: 417–429, 2006.

   
   

   M.L. Laucks, A. Sengupta, K. Junge, E.J. Davis and B.D. Swanson. Comparison of psychro-active Arctic marine bacteria and common mesophilic bacteria using surface-enhanced raman spectroscopy. Appl. Spectroscopy 10: 1222-1228, 2006.

   
   

   Deming, J. W. and K. Junge. ‘‘Colwellia’’, in The Proteobacteria, Part B, Bergey’s Manual of Systematic Bacteriology, G. T. Staley, D. J. Benner, N. R. Krieg, and G. M. Garrity, Eds. (Springer, New York, 2005), 2nd., Vol. 2, pp. 447–454, 2005.

   
   

   Junge, K., H. Eicken, and J. W. Deming. Bacterial activity at -20°C in Arctic wintertime sea ice. Appl. Environ. 70: 550-557, 2004.

   
   

   Junge, K., H. Eicken, and J. W. Deming. A Microscopic Approach to Investigate Bacteria under In-Situ Conditions in Arctic Lake Ice: Initial Comparisons to Sea Ice. In Bioastronomy 2002: Life Amongst the Stars IAU Symposium 213, eds. R. Norris and F. Stootman. Astronomical Society of the Pacific, San Francisco: 381-388, 2004.

   
   

   Junge, K., H. Eicken, and J. W. Deming. Motility of Colwellia psychrerythrea str. 34H observed at subzero temperatures. Appl. Environ. Microbiol. 69: 4282–4284, 2003.

   
   

   Skoog, A. K. Whitehead, F. Sperling, and K. Junge. Microbial glucose uptake and growth along a horizontal nutrient gradient in the North Pacific. Limnol. Oceanogr., 47(6):1676–1683, 2002.

   
   

   Krembs, C., H. Eicken, K. Junge, and J. W. Deming. High concentrations of exopolymeric substances in wintertime sea ice: Implications for the polar ocean carbon cycle and cryoprotection of diatoms. Deep-Sea Res. I 9: 2163 –2181, 2002.

   
   

   Junge, K., J.F. Imhoff, J.T. Staley and J.W. Deming. Phylogenetic diversity of numerically important Arctic sea-ice bacteria cultured at subzero temperature. Microb. Ecol. 43: 315-328, 2002.

   
   

   Junge, K., C. Krembs, J. Deming, A. Stierle and H. Eicken. A microscopic approach to investigate bacteria under in situ conditions in sea-ice samples. Ann. Glaciol. 33: 304-310, 2001.

   
   

   Staley, J. T, K. Junge, and J. Deming. And some like it cold: sea ice microbiology. In Biodiversity of Life, eds. J. T Staley and A.-L. Reysenbach, pp. 423-438, 2001.

   
   

   Junge K, J. J. Gosink, H.-G. Hoppe and J. T. Staley. Arthrobacter, Brachybacterium and Planococcus isolates identified from Antarctic sea ice brine. Description of Planococcus mcmeekenii, sp. nov. Syst Appl Microbiol 21: 306-314, 1998.