Related Experiment Video
Updated: Aug 17, 2026

Measurement of the Potential Rates of Dissimilatory Nitrate Reduction to Ammonium Based on 14NH4+/15NH4+ Analyses via Sequential Conversion to N2O
Published on: October 7, 2020
Isolation of free-living dinitrogen-fixing bacteria and their activity in compost containing de-inking paper sludge
Chantal J Beauchamp1, Gabriel Lévesque, Danielle Prévost
1Département de phytologie, Université Laval, Sainte-Foy, Québec, Canada G1K 7P4. chantal.beauchamp@plg.ulaval.ca
Abstract:
Knowledge of the microbiology of dinitrogen (N2)-fixing bacteria in compost rich in de-inking paper sludge (DPS) is limited. Dinitrogen (N2)-fixing bacteria from DPS composts were isolated and studied for their N2-fixing activity in vitro and in vivo. Two Gram-negative N2-fixing isolates were identified as Pseudomonas. At 20 degrees C, both isolates revealed that N2-fixing activity was higher than that of three arctic Pseudomonas strains. Their N2-fixing activity was found to occur between 18 and 25 degrees C, a pattern that was similar to the reference isolate Azotobacter ATCC 7486. Composts successfully showed N2-fixing activity after carbohydrate amendments both with and without inoculation of a N2-fixing isolate. These results suggest that DPS composts support N2-fixing bacteria and that N2-fixing activity is dependent on a usable carbohydrate source.
Related Concept Videos
Inorganic Nitrogen Assimilation
Overview of Nitrogen Metabolism
The largest pool of nitrogen available in the terrestrial ecosystem is gaseous nitrogen (N2) from the air, but this nitrogen...
The Roles of Bacteria and Fungi in Plant Nutrition

