Tetrachloroethylene, trichloroethylene, and chlorinated phenols induce toluene-o-xylene monooxygenase activity in Pseudomonas stutzeri OX1

Pseudomonas stutzeri OX1 naphthalene-oxidation activity is induced 3.0-fold by tetrachloroethylene (PCE) and 3.1-fold by trichloroethylene (TCE) at 10 0 muM. With the mutant P. stutzeri M1, which does not express toluene-o-xyl ene monooxygenase (ToMO, product of the tou operon), no naphthalene-oxidati on activity induction by PCE and TCE was found; hence, PCE and TCE induce T oMO of P stutzeri OX1. The chlorinated phenols 2-, 3-, and 4-chlorophenol i nduced ToMO expression 0.58-, 0.23- and 0.37-fold, respectively, compared t o the direct inducer of the pathway, o-cresol. Using P. putida PaW340 (pPP4 062, pFP3028.), which has the tou promoter fused to the reporter catechol-2 ,3-dioxygenase, and the regulator gene touR, it was determined that the tou promoter was induced directly 5.7-, 7.1-, and 5.1-fold for 2-, 3-, and 4-c hlorophenol, respectively (compared to an 8.8-fold induction with o-cresol) . In addition, it was found that TCE and PCE do not directly induce the tou pathway and that components other than the tou structural and regulatory g enes are necessary for induction. Gas chromatography results also showed th at 100 VM TCE induced its own degradation (8-9%) in 16 h in P stutzeri OX1, and all of the stoichiometric chloride from the degraded TCE was detected in solution.