Biological nitrogen fixation in the terrestrial environment of a high Arctic ecosystem (Truelove Lowland, Devon Island, N.W.T.)

• Published in: Canadian Journal of Microbiology
• Main Authors: Jordan, D. C., McNicol, Patricia J., Marshall, Margaret R.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1978
• Subjects: Genetics; Molecular Biology; Applied Microbiology and Biotechnology; General Medicine; Immunology; Microbiology; Arctic; Devon Island
• Online Access: http://dx.doi.org/10.1139/m78-108; http://www.nrcresearchpress.com/doi/pdf/10.1139/m78-108

Arranged in descending order of nitrogen-fixing (acetylene-reducing) potential the sites examined were mesic meadow and peat polygon troughs (equal rank), transition zone between mesic meadow and gravel ridge, gravel ridge, polar dessert, and peat polygon tops. The dominant nitrogen-fixing microorganisms, as in other Arctic areas, were blue-green bacteria, especially those epiphytic on Arctic mosses. The epiphytic association exhibited an optimum temperature for fixation of 20 °C. Other bacteria potentially able to fix nitrogen were present in the soils examined but their activity was severely restricted by low soil temperatures and lack of readily utilizable energy sources. These bacteria included members of the genera Klebsiella (the most numerous), Bacillus, Clostridium, and Beijerinckia (scarce). Also present at many of the sites was an unidentified yellow-pigmented fixer which was not Mycobacterium flavum. All fixers were psychrotrophic rather than psychrophilic, having an optimum temperature greater than 20 °C but capable of slow growth at 5 °C or lower. The rate of acetylene reduction by the epiphytic system increased with the number of successive exposures to acetylene, a phenomenon of some significance in any calculations designed to measure the amount of nitrogen fixed in certain ecosystems.