TRICHLOROETHYLENE DEGRADATION BY GENETICALLY-ENGINEERED BACTERIA CARRYING CLONED PHENOL CATABOLIC GENES

Pseudomonas putida BH was capable of degrading trichloroethylene (TCE) when grown on phenol, o-cresol, m-cresol or p-cresol, each of which i nduced the enzymes catalyzing the catechol catabolism through the meta -cleavage pathway. Various DNA fragments containing phenol/cresol cata bolic genes cloned from this strain were introduced into Escherichia c oli and P. putida strains by using plasmid vectors, and the resultant recombinants were examined for their TCE-degrading ability. The recomb inants harboring and expressing the phenol hydroxylase gene exhibited an ability to degrade TCE in phosphate buffer, while the rates and ext ents of TCE degradation depended considerably on the host strain and c opresence of other phenol catabolic genes. During TCE degradation by B H and recombinant E. coli, nearly complete dechlorination occurred. A recombinant E. coli strain did not require phenol as a cosubstrate for TCE degradation, the rate of which was comparable to that of fully-in duced P. putida BH. It did, however, require isopropyl-beta-thiogalact opyranoside for induction of the lac promoter on the vector.