Chlorinated solvent bioremediation: A novel approach to measuring bacterial kinetics

The industrial solvent, perchloroethylene (PCE), can be degraded by a variety of anaerobic microorganisms in situ. Kinetic analyses of these cultures are required to determine the optimal growth conditions for remediation. Because of its volatility, it is difficult to supply PCE at the constant concentration required for kinetic analyses. To overcome this problem, a bioreactor with a bed of the solid-phase sorbent Tenax was used to maintain steady-state concentrations of PCE in the aqueous phase. Our data confirm that steady-state PCE concentrations can be maintained for several months in halorespiring cultures using Tenax as a source. We have also shown that Tenax adsorbs the byproducts of dechlorination before they can accumulate to toxic levels. The anaerobic bacterial strain BB1, which gains energy by dechlorinating PCE to 1,2-cis-dichloroethene (DCE), was used in this study. 1.0 mM radiolabeled acetate with a specific activity of 0.03 mu Ci/ml was used as the sole carbon and energy source to quantify increases in biomass. Finding optimum PCE concentration ranges using the methods presented in this study may help to design more effective bioremediation strategies for the remediation of chlorinated solvents.