A Mixed Microbial Community for the Biodegradation of Chlorinated Ethenes and 1,4-Dioxane

Abstract We developed a microbial community capable of biodegrading mixtures of chlorinated ethenes and 1,4-dioxane under varying redox conditions. Achieving the removal of chlorinated ethenes as well as 1,4-dioxane to below health advisory levels in groundwater that has anaerobic and aerobic zones has proven to be challenging. However, our mixed community, composed of the anaerobic chlorinated ethene-degrading consortium KB-1 and aerobic bacterial strain, Pseudonocardia dioxanivorans CB1190, was able to reduce trichloroethene (TCE) in anaerobic environments and oxidize 1,4-dioxane in the presence of oxygen. Aerobic biodegradation of cis-1,2-dichloroethene by CB1190 was also confirmed, thus decreasing the accumulation of TCE transformation products, such as vinyl chloride. The results of this study demonstrate that the assembled microbial community not only survived significant redox changes but sequentially biodegraded chlorinated ethenes and 1,4-dioxane. This approach toward degrading mixed contaminants with a consortium containing anaerobic and aerobic bacteria provides greater insight as to when and how to transition from active enhanced reductive dechlorination to enhanced aerobic attenuation of chlorinated ethenes and 1,4-dioxane.