Induction kinetics of aerobic toluene degradation as a function of carbon starvation history

In this study, the effects of carbon starvation history on the induction kinetics of aerobic toluene degradation by Ralstonia pickettii PKO1 were quantitatively explored. Experimental results suggested that (i) the durations of the lag and transient phases depended upon both the duration of prior carbon starvation (Tstv) and the inducer concentration, and (ii) that post-transient-phase (PTP) induction levels were independent of Tstv but dependent upon inducer concentration. The observed relationships among toluene degradation, carbon starvation history, and inducer concentration were incorporated into a modified Michaelis-Menten equation in order to refine the traditional model of enzymatic biodegradation. The refined model was able to predict toluene breakthrough in a porous medium in which previously carbon-starved cells were reactivated with a continuous supply of toluene. These findings suggested a means of improving the accuracy of existing models of biodegradation in groundwater under conditions of fluctuating substrate/inducer concentration.