Deinococcus radiodurans engineered for complete toluene degradation facilitates Cr(VI) reduction

Area of Science:

• Environmental microbiology
• Bioremediation
• Biotechnology

Background:

• Toluene and radionuclides coexist at US Department of Energy sites, often with heavy metals like chromium (VI).
• Deinococcus radiodurans is highly radiation-resistant and naturally reduces Cr(VI) to less toxic Cr(III).

Purpose of the Study:

• To engineer Deinococcus radiodurans for complete toluene degradation.
• To evaluate the combined capability of degrading toluene and reducing Cr(VI) in contaminated environments.

Main Methods:

• Cloned expression of Pseudomonas putida tod and xyl genes in Deinococcus radiodurans.
• Utilized 14C-labelled toluene to track degradation pathways.
• Assessed toluene oxidation and Cr(VI) reduction in sediment microcosms under varying conditions.

Main Results:

• The engineered Tod/Xyl strain incorporated toluene carbon into cellular components and CO2, indicating degradation.
• Toluene degradation occurred in the presence and absence of ionizing radiation.
• Recombinant cells effectively reduced Cr(VI) in sediment microcosms.
• Toluene oxidation was observed under both minimal and complex nutrient conditions.

Conclusions:

• Engineered Deinococcus radiodurans (Tod/Xyl strain) can simultaneously degrade toluene and reduce Cr(VI).
• This strain shows potential for bioremediation of aerobic, radionuclide-contaminated sediments.
• The study provides a model for investigating coupled metal reduction and organic contaminant oxidation.