Biotechnology-Enabled Environmental Cleanup: Application of Molecular Techniques to Bioremediation of 1,4-Dioxane
About Dr. Mengyan Li
Dr. Mengyan “Ian” Li is an assistant professor in the Department of Chemistry and Environmental Science at New Jersey Institute of Technology, specializing in environmental microbiology and biotechnology. Prior to joining NJIT in 2015, he obtained his MS and PhD degrees in Environmental Engineering at Rice University. Dr. Li develops water remediation techniques that deploy microorganisms to biodegrade organic pollutants of emerging global concern. He also researches interdisciplinary methods for improving urban water treatment technologies. To assess microbial activities in remediation and treatment processes, he has developed genetic forensic tools, such as a novel biomarker assay to evaluate the biodegradation of 1,4-dioxane, an emerging groundwater contaminant. That work won him the Honor Award in the Excellence in Environmental Engineering and Science competition held by the American Academy of Environmental Engineers and Scientists.
About the Seminar
1,4-Dioxane (dioxane) contamination has emerged as a compelling global groundwater issue due to its carcinogenic potentials and widespread occurrence at sites historically impacted by chlorinated solvents. In situ biological treatments, including Monitored Natural Attenuation (MNA) and Bioremediation, exist as environment-benign and cost-efficient options to manage the large and diluted plume that are commonly formed by dioxane, but their field application is restricted due to the lack of the capability to monitor onsite biodegradation activities. To overcome, a primer/probe set was developed to target genes encoding bacterial monooxygenases in charge of initiating dioxane catabolism. Use of this biomarker set allowed sensitive detection of thmA/dxmA genes in field samples. Notably, a significant correlation was found between dioxane biodegradation rates and the abundance of thmA/dxmA genes, suggesting their potential as reliable indicators for rapid quantification of intrinsic biodegradation of dioxane. In a further study to research the effectiveness of various auxiliary substrates (e.g., 1-butanol and tetrahydrofuran) on stimulating dioxane biodegradation, this set of biomarker probes was employed to monitor the dynamics of dioxane metabolizers over the incubation time. Amendments with inducing and non-inducing substrates exhibited distinct effects on dioxane removal revealed by bench-scale microcosm tests, monoculture studies, and in situ BiotrapTM assays. Combination of conventional and fluorescence-activated isolation approaches also facilitated the identification of novel dioxane degraders with superior degradation capabilities from enriched consortia. Overall, state-of-the-art molecular techniques are of significant application value to uncover and assess the performance of MNA and bioremediation of dioxane plumes, which thus provide a timely scientific basis for regulatory agencies and decision makers to select or reject these cost-efficient biological remediation techniques for site clean-up.