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Updated: Mar 25, 2026

Experimental Protocol for Manipulating Plant-induced Soil Heterogeneity
Published on: March 13, 2014
Modularity of nitrogen-oxide reducing soil bacteria: linking phenotype to genotype
Constance A Roco1, Linda L Bergaust2, Lars R Bakken3
1Department of Microbiology, Cornell University, Ithaca, NY, USA.
Soil bacteria can partially reduce nitrate (NO3-) to various nitrogen oxides, not just complete denitrification to N2. This diversity means gene presence doesn't always predict N-oxide production, highlighting varied microbial functions in nitrogen cycling.
Area of Science:
- Microbial ecology
- Environmental microbiology
- Biogeochemical cycles
Background:
- Complete denitrification converts nitrate (NO3-) to dinitrogen (N2).
- Natural microbial populations may perform incomplete denitrification pathways.
- Understanding partial denitrification is crucial for soil nitrogen cycling.
Purpose of the Study:
- Investigate the diversity of partial denitrifiers in soil.
- Determine if genetic potential for N-oxide reduction aligns with observed phenotypes.
- Explore the functional roles of individual N-oxide reductases.
Main Methods:
- Isolation of soil bacteria capable of reducing nitrate (NO3-) to nitrite (NO2-).
- Measurement of N-oxide gas products from bacterial isolates.
- Genome sequencing of selected isolates to identify N-oxide reductase genes.
Main Results:
- Two of eight isolates were complete denitrifiers.
- Six isolates produced varying amounts of nitric oxide (NO) and nitrous oxide (N2O).
- Genetic analysis revealed isolates with nitrate reductase only, or combinations including nitric oxide or nitrite reductase.
Conclusions:
- N-oxide production in soil bacteria is not always predictable from genotype alone.
- Partial denitrifiers are common in soil microbial communities.
- Individual N-oxide reductases can confer selective advantages, leading to diverse nitrogen cycling pathways.
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