16S rRNA amplicon sequencing of dioxane and TCE enrichment cultures

To investigate the potential for anaerobic dioxane degradation, landfill leachate was used to establish enrichment cultures along a redox gradient (oxygen, nitrate, iron, and sulphate respiration, and fermentative) representative of common groundwater conditions. Enrichment cultures were amended with dioxane or co-contaminated with TCE. No dioxane biodegradation was observed after a 671-day period. 16S rRNA amplicon sequencing showed microbial enrichment occurred in response to the selective pressures of contaminant and redox treatment, identifying landfill microbial community members tolerant to high dioxane concentrations (i.e., 1-4 mM). Interestingly, the co-contaminated fermentative cultures degraded TCE to vinyl chloride and potentially to ethene.