Sequential Anaerobic-Aerobic Biodegradation of Trichloroethylene and 1,4-Dioxane

Chlorinated ethenes, such as trichloroethylene (TCE) and their stabilizers, such as 1,4- dioxane, are widespread groundwater contaminants. Bioremediation can be an effective approach, but opposing redox conditions favored by chlorinated ethane-and 1,4-dioxane- degrading bacteria pose a challenge for their concurrent bioremediation. We engineered a microbial community composed of the anaerobic chlorinated ethene-degrading consortium (KB-1�) and aerobic (Pseudonocardia dioxanivorans CB1190 (CB1190)) bacterial strain, which uses 1,4-dioxane. After anaerobic incubation and TCE reduction, CB1190 + KB-1� coculture was viable and rapidly biodegraded 1,4-dioxane in the presence of oxygen. Aerobic biodegradation of cis-1,2-dichloroethylene (cDCE) by CB1190 was also described. As a plume disperses downgradient, the redox conditions change from anaerobic (source zone) to aerobic (leading edge). The results from this study demonstrate that the engineered microbial community can survive redox changes and biodegrade chlorinated ethenes and 1,4-dioxane. This approach could reduce the cost, energy, and substrates required for in-situ bioremediation of contaminant mixtures.