Identification of Formate as a Principal Soluble Product from Propanotrophic Cometabolism of 1,4-Dioxane

Aerobic cometabolism is a viable method for treating groundwater contaminated with 1,4-dioxane. Although at least one biochemical pathway by which 1,4-dioxane is used as a sole source of carbon and energy has been elucidated, comparatively little is known about the products formed during cometabolic degradation. The objective of this study was to identify the main products formed during cometabolism of 1,4-dioxane by the mixed propanotrophic culture ENV487. During biodegradation of C-14-1,4-dioxane, soluble products accumulated that were concentrated by lyophilization and then separated into fractions using high-performance liquid chromatography. Formate accounted for 51% of the C-14-labeled compounds recovered, based on co-elution with authentic material. The identity of formate as the main product was confirmed using a formate dehydrogenase assay. Other products identified that represented at least 4% of the C-14 products recovered included acetate, glycerate, glycolaldehyde, ethylene glycol, and glycolate. All these compounds are readily biodegradable in an aquifer environment. This is consistent with the expectation that the endpoint for aerobic cometabolism of 1,4-dioxane by propanotrophs in a mixed culture environment is carbon dioxide.

Automated summary

The main products formed during the cometabolism of 1,4-dioxane by the mixed propanotrophic culture ENV487 were identified in this study. The results showed that formate accounted for 51% of the recovered C-14-labeled compounds, and its identity was confirmed using a formate dehydrogenase assay. Other identified products included acetate, glycerate, glycolaldehyde, ethylene glycol, and glycolate, which represented at least 4% of the recovered C-14 products. All these compounds are readily biodegradable in an aquifer environment, indicating that the endpoint for aerobic cometabolism of 1,4-dioxane by propanotrophs in a mixed culture environment is carbon dioxide.