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08:05
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
Nitrate reduction to ammonia: a dissimilatory process in Enterobacter amnigenus
Canadian Journal of Microbiology
|November 5, 2011
Summary
Seven bacterial isolates from soil were identified as dissimilatory ammonia producers, with Enterobacter amnigenus notably converting nitrate to ammonia. This process also produced nitrous oxide, with levels varying based on nitrate concentration.
Area of Science:
- Microbiology
- Environmental Science
- Biogeochemistry
Background:
- Nitrate reduction is a key microbial process in nitrogen cycling.
- Understanding dissimilatory nitrate reduction to ammonia (DNRA) is crucial for soil ecosystems.
- Denitrification is another significant pathway for nitrate removal.
Purpose of the Study:
- To investigate nitrate reduction pathways in soil bacterial isolates.
- To identify bacteria capable of dissimilatory ammonia production and denitrification.
- To characterize the process of ammonia production by Enterobacter amnigenus.
Main Methods:
- Isolation and testing of 34 bacterial strains from agricultural soil.
- Culturing in nitrate broth and glucose-enriched minimal medium.
- Quantification of ammonia and nitrous oxide production.
- Use of (15)N-labeled Enterobacter amnigenus to confirm dissimilatory pathways.
Main Results:
- Ten isolates were identified as denitrifying bacteria.
- Seven isolates were identified as dissimilatory ammonia producers.
- Enterobacter amnigenus produced significant amounts of ammonia from nitrate.
- Nitrous oxide was co-produced with ammonia during nitrite reduction.
- Nitrate concentration influenced the balance between ammonia, nitrite, and nitrous oxide production.
Conclusions:
- Soil bacteria exhibit diverse nitrate reduction capabilities, including significant ammonia production.
- Enterobacter amnigenus is a notable dissimilatory ammonia producer.
- Environmental factors, such as nitrate availability, modulate these microbial processes.
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