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Bioremediation is an attractive in-situ remedial strategy for contaminated sites that are able to sustain microbial populations capable of degrading compounds of interest. While some microorganisms can grow on certain contaminants, many others can cometabolize contaminants. In cometabolism, microorganisms are able to transform a compound but in doing so, they receive no carbon or energy that supports their survival. While this process is undesirable for the organism, it can be used by engineers as a way to remediate soil and groundwater effectively and at low costs.

Mycobacterium Sp. strain ELW1 is one such microorganism. When grown on the gas isobutene, ELW1 has demonstrated cometabolic capabilities with many compounds containing a double bond. This activity is attributed to a monooxygenase enzyme that is used in ELW1’s central metabolism. In this project, ELW1’s cometabolic capabilities were first assessed with a chlorinated aliphatic hydrocarbon (CAH) cis-1,2-dichloroethylene (cis-DCE). Rates of cometabolism of both cis-DCE and its primary transformation product, cis-DCE epoxide, were determined in resting cell tests using gas chromatography with an electron capture detector (GC-ECD). This data will inform future experiments investigating ELW1’s cometabolism of aromatic compounds, namely polycyclic aromatic hydrocarbons (PAHs).

PAHs are a class of ubiquitous environmental contaminants that have both anthropogenic and natural sources. Their persistence in the environment combined with the health hazards they pose to humans and aquatic life has landed several PAHs on the EPA’s priority pollutant list. Previous work with ELW1 and the PAH phenanthrene revealed that while ELW1 can cometabolize phenanthrene, the toxicity of the resulting mixture was enhanced by ELW1’s activity. This project aims to assess remedial strategies for PAHs, including bioremediation via cometabolism, and identify the strategy or combination of strategies that minimizes the hazards associated with a PAH contaminated site.

This project presenter is available for live video chat on Sept. 1, 2020 from 1:00 - 2:45 p.m. PDT.