1 Isolation and physiological characterization of psychrophilic denitrifying bacteria 2 from permanently cold Arctic fjord sediments (Svalbard, Norway) 3 4 ‡ ‡ 5 Andy Canion1 , Om Prakash1 , Stefan J. Green2, Linda Jahnke3, Marcel M. M. 6 Kuypers4 and Joel E. Kostka5* 7 8 1 Earth Ocean and Atmospheric Science Dept., Florida State University, Tallahassee, FL 9 2 DNA Services Facility, University of Illinois at Chicago, Chicago, IL 10 3 NASA Astrobiology Institute, Ames Research Center, Moffett Field, CA 11 4 Max Planck Institute for Marine Microbiology, Bremen, Germany 12 5 School of Biology, Georgia Institute of Technology, Atlanta, GA 13 ‡ 14 These authors contributed equally to this work 15 16 *Corresponding author mailing address: 17 Joel E. Kostka 18 Georgia Institute of Technology 19 Schools of Biology and Earth & Atmospheric Sciences 20 Room 225, Cherry Emerson Bldg. 21 310 Ferst Drive 22 Atlanta, Georgia 30332-0230 23 Phone: 404-385-3325 24 Fax: 404-894-0519 25 Email address:
[email protected] 26 27 Key Words: Psychrophile / denitrification /temperature 28 Running Title: Denitrifying Bacteria in Arctic Sediments Denitrifying Bacteria in Arctic Sediments 29 ABSTRACT 30 A large proportion of reactive nitrogen loss from polar sediments is known to be mediated by 31 denitrification. However, the microorganisms mediating denitrification in polar 32 environments remain poorly characterized. A combined approach of MPN enumeration, 33 cultivation, and physiological characterization was used to describe psychrophilic 34 denitrifiying bacterial communities in sediments of three Arctic fjords in Svalbard (Norway). 35 The physiological response of representative isolates to temperature was examined by 36 quantifying growth rates, nitrate depletion, and membrane lipid composition across a 37 temperature gradient.