Metabolism of polyhalogenated compounds by a genetically engineered bacterium

Area of Science:

• Environmental microbiology
• Bioremediation
• Synthetic biology

Background:

• Microbial decomposition of organic compounds is well-established, but metabolizing highly halogenated compounds remains a challenge.
• Polyhalogenated compounds are typically degraded by sequential anaerobic and aerobic bacterial processes.
• Previous attempts to isolate pure cultures for metabolizing these pollutants have been largely unsuccessful.

Purpose of the Study:

• To develop a single bacterial strain capable of metabolizing highly halogenated compounds.
• To engineer a Pseudomonas strain for sequential reductive and oxidative degradation pathways.
• To create a bioremediation strategy for persistent halogenated pollutants.

Main Methods:

• Combined seven genes encoding two multi-component oxygenases into a single Pseudomonas strain.
• Utilized Cytochrome P450cam monooxygenase for reductive dehalogenation under low oxygen.
• Demonstrated that reduction products serve as substrates for toluene dioxygenase.

Main Results:

• The engineered Pseudomonas strain successfully metabolizes polyhalogenated compounds via sequential reactions.
• Non-toxic end products are generated from the degradation of halogenated pollutants.
• Perhalogenated chlorofluorocarbons were also identified as substrates for the engineered strain.

Conclusions:

• A single genetically engineered bacterial strain can achieve complete metabolism of polyhalogenated compounds.
• This approach integrates anaerobic and aerobic degradation steps within one organism.
• The engineered strain shows potential for bioremediation of diverse halogenated pollutants, including chlorofluorocarbons.