Collaborative Research: IPY Microbial subzero activity and its impact on biogeochemical processes in frozen tundra and permafrost.   NSF 0732956-Jan, 2008-Dec, 2010

The overall goal of the proposed work is to understand subzero microbial processes and their impacts on permafrost dynamics, thermal degradation, and carbon cycling.  Researchers at Rutgers are working with Nicolai Panikov from Northeastern University and Tingjun Zhang at the National Snow and Ice Data Center (NSIDC) at the University of Colorado, Boulder.  Our research plan includes:  1) intensive laboratory studies with samples taken from Toolik Lake and Fairbanks, Alaska and 2) extensive studies on circumpolar samples around the Arctic Circle. The Rutgers Group is responsible for molecular ecology of permafrost samples and stable isotope probing (SIP) to ascertain active microbes in samples collected around the Arctic Circle.

During the initial year of the project, there was an opportunity to attempt an in situ SIP experiment in Kilpisjärvi, Finland (69^o N).  The 2 PI's from Rutgers joined researchers from the Finnish Forest Research Institute (figure 1) to attempt this in situ SIP experiment above tree line, near Maala Fell. 

Once in Finland, a series of 250 sample spots were established on the slope of Maala Fell and 15 substrates labeled with heavy isotopes were randomly assigned and injected into the soil at each location (figure 2).  The substrates were ¹³C or ¹⁵N labeled benzoic acid, ethanol, methanol, glycine, cellobiose, glutamic acid, acetate, palmitolenic acid, nitrate, ammonium, urea-¹⁵N, and urea-¹³C. At the end of each incubation, a smaller corer was used to harvest injected soil and processed in the field before freezing in liquid N₂.  

The preliminary data indicates that Arctic bacteria can incorporate C into newly synthesized DNA over short time frames.  Completion of this Finnish SIP experiment will address issues of metabolic partitioning in microbial communities in Arctic soils and identify those active microorganisms in situ.  This pilot study in Finland will aid in experimental design to inject permafrost cores in Alaska in situ once methods for substrate distribution with out increasing the soil temperature have been worked out.  Laboratory studies using the Finnish soil were also conducted at Rutgers.  Preliminary findings were presented at the American Society of Microbiology General Meeting in summer of 2009 at Philadelphia, PA.

About Lee Kerkhof

Lee Kerkhof began his training as a research scientist in the early 80's in a Drosophila and an Environmental Chemistry lab at Harvard University where he learned the fundamentals of recombinant DNA technology and stable isotope rate measurements.  In the late 80's, he became a graduate student with Dr. Bess Ward at Scripps Institution of Oceanography/UC San Diego.  His thesis project was developing a species-specific growth rate assay by measuring ribosomal RNA content in marine bacteria. Lee's post-doctoral experience with Dr. Paul Kemp at Brookhaven National lab continued this research.  
Dr. Kerkhof became a faculty member at Rutgers in 1994 and is currently a professor in the Department of Marine and Coastal Sciences.  His research focuses on using a nucleic acid fingerprinting techniques to provide information on the active bacteria in a variety of samples including the Mid-Atlantic Bight system, wastewater bioreactors developed by NASA, tropical river plumes, pollutant degrading microcosms, and coastal sediments.  Current projects involve studying microbial populations in marine sponges, Arctic soils, and in uranium contaminated plumes in the continental subsurface.  During the last 3 years, Dr. Kerkhof has served as an ad Hoc Mail Reviewer/Panel Member for the National Science Foundation and the U. S. Dept. of Energy.  He is a member of the editorial board for Applied Environmental Microbiology and is an ad-hoc Mail reviewer for FEMS Microbial Ecology, Science, Aquatic Microbial Ecology, and ISME Journal manuscripts.   Currently, he is Chair- Div. N (Microbial Ecology) for American Soc. of Microbiology.