Related Experiment Videos
Steady-state nitric oxide concentrations during denitrification
J Goretski1, O C Zafiriou, T C Hollocher
1Department of Biochemistry, Brandeis University, Waltham, Massachusetts 02254.
The Journal of Biological Chemistry
|July 15, 1990
Summary
Denitrifying bacteria produce nitric oxide (NO) as a steady-state intermediate. Low levels of NO were detected during denitrification, suggesting efficient nitric oxide reductase activity.
Area of Science:
- Microbiology
- Environmental Science
- Biochemistry
Background:
- Denitrification is a crucial microbial process in nitrogen cycling.
- Nitric oxide (NO) is a gaseous intermediate in denitrification.
- Understanding NO's role is vital for microbial ecology and environmental studies.
Purpose of the Study:
- To investigate the steady-state concentration of nitric oxide (NO) during bacterial denitrification.
- To determine if NO functions as a stable intermediate in the denitrification pathway.
- To assess the activity of nitric oxide reductase in vivo.
Main Methods:
- Anaerobic incubation of denitrifying bacteria (Paracoccus denitrificans, Pseudomonas stutzeri, Achromobacter cycloclastes) with nitrate or nitrite.
- Gas-phase analysis of NO using chemiluminescence detection.
- Calculation of aqueous NO concentrations ([NOaq]) from gas-phase measurements and NO solubility.
Main Results:
- Nitric oxide (NO) was detected as a steady-state intermediate during denitrification by three bacterial species.
- Steady-state [NOaq] ranged from 1 to 65 nM, independent of initial substrate or cell concentrations.
- NO levels were stable over time and quickly re-established after perturbation, consistent with a steady-state intermediate.
Conclusions:
- Nitric oxide (NO) is a transient, steady-state intermediate in bacterial denitrification.
- The low observed [NOaq] suggests high in vivo activity of nitric oxide reductase.
- This efficient NO metabolism prevents toxic accumulation of NO during denitrification.