Kinetics of biotransformation of 1,1,1-trichloroethane by Clostridium sp. strain TCAIIB

Abstract

Batch experiments were conducted to examine the effects of high concentrations of 1,1,1-trichloroethane (TCA) on the biotransformation of TCA by Clostridium sp. strain TCAIIB. The biotic dehalogenation of TCA to 1,1-dichloroethane by nongrowing cells was measured at 35°C, and the data were used to obtain the kinetic parameters of the Monod relationship half-velocity coefficient K(s) (31 μM) and the coefficient of maximum rate of TCA biotransformation (k(TCA); 0.28 μmol per mg per day). The yield of biomass decreased with an increase in the TCA concentration, although TCA concentrations up to 750 μM did not completely inhibit bacterial growth. Also, k(TCA) was higher in the presence of high concentrations of TCA. A mathematical model based on a modified Monod equation was used to describe the biotransformation of TCA. The abiotic transformation of TCA to 1,1-dichloroethene was measured at 35°C, and the first-order formation rate coefficient for 1,1-dichloroethene (k(e)) was determined to be 0.86 per year.