Characterization of the requirements and substrates for reductive dehalogenation by strain DCB-1

An obligately anaerobic bacterium known as strain DCB-1 was grown under a variety of conditions to determine the requirements for dehalogenation as well as factors which stimulated or inhibited the process. Dechlorination was obligately anaerobic since introduction of O2 immediately inhibited the reaction. Sulfuroxy anions, which also serve as electron acceptors for DCB-1, inhibited dechlorination but NO3- and fumarate did not. The optimum growth medium for dechlorination was 0.2% Na pyruvate and 20% rumen fluid in basal salts. Media with either pyruvate or rumen fluid alone did not support dechlorination. DCB-1 also consumed H2 but typical substrate concentrations of H2 (80 kPa) delayed dechlorination. Once the H2 concentration was reduced to less than 20 microM (2.67 kPa), dechlorination resumed. Dehalogenation by DCB-1 was restricted to the meta substituted benzoates as halogens in other positions and chloroaromatic compounds with other functional groups were not dechlorinated.