Microbial dechlorination of low concentration polychlorinated biphenyls as affected by rhamnolipid biosurfactant

In the present study, we investigated the effect of the rhamnolipid biosurfactant on the threshold level for dechlorination at polychlorinated biphenyl (PCB) concentrations of40, 60 and 120 ppm. When the extent of dechlorination was examined with the time course of incubations, the surfactant amendment enhanced the rate of dechlorination at all concentrations and the rate was also faster at higher concentrations. On a congener group basis, dechlorination proceeded primarily with group A in both surfactant-free and amended sediments, accumulating mainly group C congeners, and surfactant enhanced the dechlorination rate of most groups A congeners. However, surfactant did not change the congener specificity nor broaden the congener spectrum for dechlorination of the inoculum.