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Chloroform mineralization by toluene-oxidizing bacteria
K McClay1, B G Fox, R J Steffan
1Envirogen, Inc., Lawrenceville, New Jersey 08648, USA.
Applied and Environmental Microbiology
|August 1, 1996
Summary
Certain toluene-oxidizing bacteria can degrade chloroform (CF), with strain ENVBF1 showing the highest degradation rate. This microbial degradation process converts CF into CO2, metabolites, and bound carbon, with potential applications in bioremediation.
Area of Science:
- Environmental microbiology
- Bioremediation
- Biocatalysis
Background:
- Chloroform (CF) is a persistent environmental pollutant.
- Toluene-oxidizing bacteria possess enzymes capable of degrading halogenated compounds.
- Understanding microbial degradation pathways is crucial for developing bioremediation strategies.
Purpose of the Study:
- To evaluate the efficacy of seven toluene-oxidizing bacterial strains in degrading chloroform.
- To identify the primary degradation products of chloroform by these bacteria.
- To investigate the influence of other halogenated compounds on chloroform degradation.
Main Methods:
- Incubation of bacterial strains with chloroform and measurement of oxidation rates.
- Use of [14C]-labeled chloroform to trace degradation pathways.
- Analysis of culture extracts to identify mineralization products (CO2, chloride ions) and metabolites.
Main Results:
- Strain ENVBF1 exhibited the highest chloroform oxidation rate (1.9 nmol/min/mg protein).
- Mineralization of chloroform yielded CO2 (30-57%), soluble metabolites (15%), and bound carbon (30%).
- Trichloroethylene inhibited CF oxidation, while acetylene inhibited trichloroethylene oxidation by specific strains.
Conclusions:
- Toluene-oxidizing bacteria, particularly strain ENVBF1, demonstrate significant potential for chloroform biodegradation.
- The degradation pathway involves mineralization to CO2 and chloride ions, with intermediate metabolites.
- Enzyme inhibition studies suggest complex interactions between different halogenated compounds and microbial degradation pathways.