FEASIBILITY OF WASTE-WATER TREATMENT USING GENETICALLY ENGINEERED MICROORGANISMS

The feasibility of wastewater treatment using genetically engineered xenobiotic-degrading microorganisms was discussed. The degradation activity and the plasmid stability of some Escherichia coli and Pseudomonas putida strains harboring the recombinant plasmids containing salicylate oxidase gene or catechol 2,3 oxygenase gene were investigated. A few recombinants showed higher degradation activity than those of the wild strains. On the other hand, the recombinant plasmids were unstable in the absence of selective pressure. Both the degradation activity and the plasmid stability were affected considerably by the combination of plasmids and recipients. In another experiment, NAH plasmid was transferred into a floc-forming bacteria, Pseudomonas lemoignei 551 by conjugation, and floc-forming and salicylate-degrading bacteria were bred. This genetically engineered bacteria which grows flocculently seems to be maintained stably in activated sludge or in the wastewater treatment process. From these experimental results, the availability of the application of GEMs was demonstrated, and the possibility of solving two major problems, the genetic stability and the ecological stability, was suggested.