Anaerobic Microbial Metabolism of Environmental Contaminants, Microbial Ecology

Microorganisms are critical to the cycling of both organic and inorganic compounds in the environment including key elements such as nitrogen and sulfur. Without their activity the world would be a deserted wasteland. Dr. Lily Young's lab focuses on how naturally occurring microbes in the environment are able to cycle resistant carbon compounds such as petroleum components in anoxic environments like harbor sediments and groundwater. We target novel anaerobes and the chemistry of the degradation pathways that they carry out. Recent work also targets the activity of environmental microbes on the reduction and oxidation (and cycling) of arsenic found in groundwater both locally and worldwide, processes that affect environmental toxicity.

Anaerobic Biodegradation of Hydrocarbons

Petroleum hydrocarbon compounds including benzene, toluene, xylenes, naphthalene, phenanthrene, and hexadecane, are no longer considered recalcitrant under anaerobic conditions. We have proven that anaerobes have novel mechanisms to activating these molecules. For toluene the bssA gene codes for benzyl-succinate synthase and we have shown that different anaerobes have analogues of bssA to degrade naphthalene and hexadecane. We also demonstrate that some anaerobes have a different and unique mechanism for hexadecane degradation involving glycyl radical chemistry. These anaerobic mechanisms are underexplored in anoxic habitats and for remediation of these contaminants.

Microbial Arsenic Cycling

We have shown that different microorganisms can obtain energy for growth from either the oxidation of arsenite (As III) or the reduction of arsenate (As V). In the latter, they are respiring arsenate under anaerobic conditions, and in the former, they are growing aerobically through autotrophic fixation of CO2. This allowed us to demonstrate that arsenic can cycle between these two oxidation states with 1 organism carrying out each process and with only the redox conditions being changed. Microorganisms, therefore, may also play a role in the cycling of other hazardous metals in the environment.

Other Highlights

Dr. Young has served as Dean of Graduate Programs at the School of Environmental and Biological Sciences (SEBS) and as Chair of the Department of Environmental Sciences. She is currently Dean of International Programs at SEBS.