Article Abstract:
Pseudomonas cepacia G4 causes the degradation of trichloroethylene (TCE) by a pathway for aromatic compounds induced by substrates such as phenol and tryptophan. Pseudomonas cepacia G4 5223 PR1(PR1) is a Tn5 insertion mutant which expresses the toulene ortho-monooxygenase responsible for TCF degradation. In ground water microcosms, phenol-induced strain G4 and noninduced strain PR1 caused degradation to TCE to nondetectable levels within 24 hours at densities of 108 cells per milliliter. At lower densities degradation of TCE was not noticed after 48 hours. Aquifer sediment microcosms, indicated that TCE diminished from 60 to < 0.1 micro mols within 24 hours at 5 x 108 PR1 organisms per gram (wet weight) of sediment and from 60 to 26 micro mols over a period of 10 weeks at 5 x 107 PR1 organisms per gram.
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Article Abstract:
Two pseudomonad species designed to degrade substituted aromatic compounds were introduced into activated sludge microcosms to determine their survival, expression of engineered catabolic pathways and ability to transfer engineered plasmids. The results showed that the engineered bacteria could survive and grow under environmental conditions. They were also able to express their respective engineered catabolic pathways. In addition, in situ horizontal transfer of plasmid DNA was observed. The last observation has implications in the potential risk associated with the release of genetically-engineered microorganisms in the environment.
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Article Abstract:
A genetically engineered microorganism (GEM), Pseudomonas sp. strain B13 FR1, was created via a constructed ortho cleavage pathway. This organism is capable of degrading chloro- and methylaromatics. The fate and function of of this GEM in aquatic sediments was investigated with the use of a microcosm system model. The genetically engineered Pseudomonad survived in the microcosm system for four weeks and increased the degradation rate of exogenously applied 3-chlorobenzoate and 4-methybenzoate. These results suggest that this GEM is potentially useful for bioremediation.
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