Related Experiment Videos
Aerobic denitrification in various heterotrophic nitrifiers
L A Robertson1, R Cornelisse, P De Vos
1Institute for Biotechnology, Delft University of Technology, The Netherlands.
Antonie Van Leeuwenhoek
|November 1, 1989
Summary
Heterotrophic nitrifying bacteria can also perform aerobic denitrification, utilizing both oxygen and nitrate. This dual electron acceptor use enhances growth rates but may reduce yield compared to oxygen alone.
Area of Science:
- Microbiology
- Environmental Science
- Biochemistry
Background:
- Heterotrophic nitrifiers are microorganisms capable of converting ammonia to nitrate.
- Aerobic denitrification is a process where nitrate is reduced in the presence of oxygen.
- Understanding microbial metabolism of nitrogen compounds is crucial for environmental processes.
Purpose of the Study:
- To investigate the dual function of heterotrophic nitrifiers as aerobic denitrifiers.
- To characterize the growth kinetics and metabolic pathways of a specific strain under dual electron acceptor conditions.
- To compare the denitrification capabilities of different microbial strains.
Main Methods:
- Cultivation of microbial strains in chemostats.
- Measurement of nitrification and denitrification rates.
- Enzyme activity assays to determine pathway regulation.
Main Results:
- Various heterotrophic nitrifiers were identified as aerobic denitrifiers.
- One strain, "Pseudomonas denitrificans", exhibited high nitrification and denitrification rates.
- This strain required nitrate reductase induction, unlike Thiosphaera pantotropha, but possessed a constitutive denitrification pathway.
Conclusions:
- Heterotrophic nitrifiers can efficiently utilize both oxygen and nitrate as electron acceptors.
- "Pseudomonas denitrificans" demonstrates significant nitrification and denitrification potential.
- The regulation of nitrate reductase is strain-specific, while other denitrification enzymes appear constitutive.