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Anaerobic benzene biodegradation linked to nitrate reduction
1Department of Civil Engineering, McMaster University, Hamilton, Ontario.
Applied and Environmental Microbiology
|January 30, 1999
Summary
Benzene biodegradation coupled with nitrate reduction was observed in soil and groundwater. This process yielded less biomass than predicted, with most benzene converted to carbon dioxide.
Area of Science:
- Environmental Microbiology
- Biogeochemistry
- Bioremediation
Background:
- Benzene is a common environmental pollutant.
- Nitrate reduction is a key microbial process in anoxic environments.
- Coupling pollutant degradation to alternative electron acceptors is crucial for bioremediation.
Purpose of the Study:
- To investigate the biodegradation of benzene linked to nitrate reduction.
- To quantify the stoichiometry and efficiency of this process.
- To elucidate the role of intermediate reduction products.
Main Methods:
- Enrichment culture development from soil and groundwater.
- Use of [14C]benzene to track degradation and incorporation.
- Measurement of nitrate, nitrite, and carbon dioxide.
- Electron balance calculations.
Main Results:
- Benzene biodegradation was directly linked to nitrate reduction at a 1:10 molar ratio.
- Cell yield was low (8.8 g/mol benzene), representing <15% of predicted values.
- 92-95% of benzene carbon was mineralized to CO2, with 5-8% incorporated into biomass.
- Benzene degradation ceased when nitrate was depleted and only nitrite remained.
- Benzene biodegradation was more tightly coupled to nitrate reduction to nitrite.
Conclusions:
- Benzene can be biodegraded using nitrate as an electron acceptor.
- The process is inefficient in terms of biomass yield.
- Benzene biodegradation is more strongly coupled to the partial reduction of nitrate to nitrite than to complete denitrification.