Multiphasic kinetics of transformation of 1,2,4-trichlorobenzene at nano- and micromolar concentrations by Burkholderia sp. strain PS14.

The transformation of 1,2,4-trichlorobenzene (1,2,4-TCB) at initial concentrations in nano- and micromolar ranges was studied in batch experiments with Burkholderia sp. strain PS14. 1,2,4-TCB was metabolized from nano- and micromolar concentrations to below its detection limit of 0.5 nM. At low initial 1,2,4-TCB concentrations, a first-order relationship between specific transformation rate and substrate concentration was observed with a specific affinity (a(0)(A)) of 0.32 liter. mg (dry weight)(-1). h(-1) followed by a second one at higher concentrations with an a(o)(A) of 0.77 liter. mg (dry weight)(-1). h(-1). This transition from the first-order kinetics at low initial 1,2,4-TCB concentrations to the second first-order kinetics at higher 1,2,4-TCB concentrations was shifted towards higher initial 1,2,4-TCB concentrations with increasing cell mass. At high initial concentrations of 1,2,4-TCB, a maximal transformation rate of approximately 37 nmol. min(-1). mg (dry weight)(-1) was measured, irrespective of the cell concentration.