Research Product

Intact cells of Pseudomonas cepacia strain G4 completely degraded trichloroethylene (TCE) following growth with phenol. Degradation kinetics were determined for both phenol, used to induce requisite enzymes, and TCE, the target substrate. Apparent Ks and Vmax values for degradation of phenol by cells were 8.5 µM and 466 nmol/min per mg protein, respectively. At phenol concentrations above 50 µM, phenol degradation was inhibited, yielding an apparent kSI of 0.45 mM as modeled by the Haldane expression. A partition coefficient for TCE was determined to be 0.40 +/- 0.02, [TCE air]/[TCE water], consistent with Henry's law. To eliminate experimental problems associated with TCE volatility and partitioning, a no-headspace bottle assay was developed allowing for direct and accurate determinations of aqueous TCE concentration. By this assay procedure, apparent Ks and Vmax values determined for TCE degradation by intact cells were 5.6 µM and 7.9 nmol/min per mg protein, respectively. Following a transient lag period, P. cepacia G4 degraded TCE at concentrations of at least 300 µM TCE with no apparent retardation in rate. Consistent with Ks values determined for degradation, TCE significantly inhibited phenol degradation.