Enhancement of Trichloroethylene Degradation in Aquifer Microcosms Bioaugmented with Wild Type and Genetically Altered Burkholderia (Pseudomonas) cepacia G4 and PR1

Abstract

The effects of bioaugmentation on the aerobic cometabolism of trichloroethylene (TCE) in groundwater were investigated using small-column aquifer microcosms. Nonsterile nonbioaugmented microcosms fed phenol as a primary substrate mimicked observed in-situ behavior at the Moffett Field site (1), cometabolizing approximately 60 μg/L TCE while fed 6.5 mg/L phenol. High-density single bioaugmentation with Burkholderia (Pseudomonas) cepacia G4 increased TCE removal in sterile aquifer material, while producing mixed results in nonsterile material. Low-density semicontinuous bioaugmentation enhanced TCE transformation in nonsterile microcosms. A nonrecombinant NTG-induced mutant of G4 (PR1 301 ) capable of uninduced constitutive degradation of TCE in the absence of phenol or toluene was developed for environmental release. Phenol-fed microcosms augmented with either B. cepacia strain G4 or PR1 301 transformed twice as much TCE as the nonaugmented phenol-fed microcosm. In addition, should primary substrate addition be a regulatory concern, TCE degradation was observed without primary substrate addition through bioaugmentation using organisms expressing the TCE-transforming enzyme.