Biomarkers and bioremediation solutions for 1,4-dioxane contamination

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1,4-dioxane is a common groundwater contaminant and likely human carcinogen. As such, 1,4-dioxanerepresents an environmental and human health hazard. Dioxane is a common co-contaminant in many activeand retired industrial sites where it can prevent remediation of co-occurring, high-priority contaminants such aschlorinated solvents. Understanding the capacity for 1,4-dioxane attenuation and bioremediation at acontaminated site is thus important to environmental protection agencies, site owners, and the general public.The proposed research has concurrent aims of identifying biomarkers for microbially-mediated 1,4-dioxanedegradation and development of 1,4-dioxane degrading enrichment cultures as potential bioremediation tools.The work will include field sampling two 1,4-dioxane contaminated sites - a southern Ontario landfill and aformer chemical plant in Southeast Texas. Microbial biomass will be filtered from landfill leachate andgroundwater. Environmental microbes will be characterized through metagenomic sequencing, and 1,4-dioxanedegraders cultivated and their activities characterized. Genes involved in 1,4-dioxane degradation will beidentified from the sampled sites as well as from public metagenome sequences from diverse environments,defining the prevalence and potential for 1,4-dioxane degradation across the globe. Accurate site assessmentand access to cost-effective bioremediation options will have strong economic benefits for site owners. Basedon dioxane's toxicity and prevalence, maximum contaminant levels are expected to be implemented byEnvironment Canada and the U.S. Environmental Protection Agency within the next few years. Developmentof biomarkers to assess the potential for 1,4-dioxane degradation and establishment of bioremediation tools arethus proactive steps to ensure Canadian policy makers and site owners have rapid, appropriate responses tonewly established maximum contaminant levels.