Quantification of toluene dioxygenase induction and kinetic modeling of TCE cometabolism by Pseudomonas putida TVA8

As measured by the toluene‐induced bioluminescent response of Pseudomonas putida TVA8 in batch experiments, toluene dioxygenase (Tod) enzyme activities are dependent on toluene concentration between 0 and 30 mg/L. To provide a measure of the Tod activity for use in Michaelis‐Menten competitive‐inhibition kinetics, a correlation between toluene concentration and induced Tod activity as measured by an induced bioluminescent response of P. putida TVA8 is presented as a nondimensional Tod activity parameter. A packed‐bed, radial‐flow bioreactor (RFB) using the bioreporter P. putida TVA8A serves as the model system for studying the effect of the enzyme activity parameter on model predictions of vapor‐phase toluene oxidation and trichloroethylene (TCE) cometabolism. Mass balances were performed on a differential section of the RFB to describe the radial transport of vapor‐phase toluene and TCE through a bulk gas phase and the concomitant biological reaction in a stationary biofilm phase. The finite‐element Galerkin weak‐statement formulation with first‐order basis functions was used to find the optimum solution to the highly nonlinear, coupled equations. For this RFB system with toluene concentrations less than 1 mg/L in the bulk gas phase, the Tod activity parameter enables accurate predictions of steady‐state TCE degradation rate (0.27 μg TCE/min). © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 76: 341–350, 2001.