DEGRADATION OF TRICHLOROETHYLENE BY PSEUDOMONAS-CEPACIA G4 AND THE CONSTITUTIVE MUTANT STRAIN G4-5223 PR1 IN AQUIFER MICROCOSMS

pseudomonas cepacia G4 degrades trichloroethylene (TCE) via a degradat ion pathway for aromatic compounds which is induced by substrates such as phenol and tryptophan. P. cepacia G4 5223 PR1 (PR1) is a Tn5 inser tion mutant which constitutively expresses the toluene ortho-monooxyge nase responsible for TCE degradation. In groundwater microcosms, pheno l-induced strain G4 and noninduced strain PR1 degraded TCE (20 and 50 muM) to nondetectable levels (<0.1 muM) within 24 h at densities of 10 (8) cells per ml; at lower densities, degradation of TCE was not obser ved after 48 h. In aquifer sediment microcosms, TCE was reduced from 6 0 to <0.1 muM within 24 h at 5 x 10(8) PR1 organisms per g (wet weight ) of sediment and from 60 to 26 muM over a period of 10 weeks at 5 x 1 0(7) PR1 organisms per g. Viable G4 and PR1 cells decreased from appro ximately 10(7) to 104 per g over the 10-week period.