Degradation of trichloroethylene by Pseudomonas cepacia G4 and the constitutive mutant strain G4 5223 PR1 in aquifer microcosms

Abstract

Pseudomonas cepacia G4 degrades trichloroethylene (TCE) via a degradation pathway for aromatic compounds which is induced by substrates such as phenol and tryptophan. P. cepacia G4 5223 PR1 (PR1) is a Tn5 insertion mutant which constitutively expresses the toluene ortho-monooxygenase responsible for TCE degradation. In groundwater microcosms, phenol-induced strain G4 and noninduced strain PR1 degraded TCE (20 and 50 μM) to nondetectable levels (<0.1 μM) within 24 h at densities of 108 cells per ml; at lower densities, degradation of TCE was not observed after 48 h. In aquifer sediment microcosms, TCE was reduced from 60 to <0.1 μM within 24 h at 5 x 108 PR1 organisms per g (wet weight) of sediment and from 60 to 26 μM over a period of 10 weeks at 5 x 107 PR1 organisms per g. Viable G4 and PR1 cells decreased from approximately 107 to 104 per g over the 10-week period.