Modeling the role of metabolic intermediates in kinetics of phenol biodegradation

The kinetics of phenol biodegradation by Pseudomonas putida ATCC 49451 in batch cultures were investigated over a wide range of initial phenol concentrations (25-800 mg/l). Although the Haldane equation could model specific growth rate as a function of initial phenol concentrations very well, it was found inadequate to describe phenol degradation profiles, especially for cultures containing high initial phenol concentrations (e.g. 800 mg/l). This was attributed to the inhibition of metabolic intermediates of phenol degradation and the variable cell mass yield. Consequently, a new phenol degradation model was proposed. By incorporating the inhibition effects of metabolic intermediates, the new model successfully simulated phenol degradation profiles in the entire range of initial phenol concentrations studied by using only one set of model parameters. Based on a comparison of the new model with the conventionally used Haldane equation, it is concluded that the inhibition of metabolic intermediates plays a crucial role in phenol degradation modeling, especially over a wide concentration range of phenol. (C) 1999 Elsevier Science Inc. All rights reserved.