RECOMBINANT GFP-TAGGED ROOT-COLONIZING MICROBES: IMPLICATIONS ON PHYTOREMEDIATION

摘要

At numerous field sites poplar trees are known to impact chlorinated volatile organic compounds (VOC), including trichloroethylene (TCE), however the fate is uncertain. Work presented here targets enhancing the degradation of TCE and other chlorinated solvents in situ through rhizoremediation. Rhizoremediation relies on the symbiosis between plants and microorganisms to degrade contaminants in soil and groundwater. In current studies, the enhanced growth of recombinant, root-colonizing microorganisms is observed, and the potential for more effective treatment is evaluated through the use of green fluorescence protein (GFP). GFP is a useful marker to detect the activity and growth patterns of these recombinant microorganisms. Microbes isolated from poplar tree root were tagged with the gfp gene, which encodes the GFP from Aequorea victoria. The same host organisms have also been engineered to express toluene ortho-monoxygenase (TOM) enzymes to degrade chlorinated solvents. The gfp gene is expressed constitutively in the microbes, as the purified plasmid chromosomally integrated the gfp gene into the microorganisms. Each of the recombinant isolates is stable for at least 100 generations and have growth rates similar to the host strains, indicating that the selective advantages for root colonization are retained. The use of GFP has elucidated the colonization patterns of each recombinant microbe. Through using the gfp- and TOM-recombinants information regarding the efficacy and survivability of the microorganisms under different conditions can be understood.