Northwestern University

Fri 2:00 PM

EES Seminar: Morgan Petrovich

When: Friday, May 10, 2019
2:00 PM - 3:00 PM  

Where: Technological Institute, A230, 2145 Sheridan Road, Evanston, IL 60208 map it

Audience: Faculty/Staff - Student - Public - Post Docs/Docs - Graduate Students

Contact: Tierney Acott   847.491.3257

Group: McCormick - Civil and Environmental Engineering

Category: Lectures & Meetings


Metagenomics-Guided Analysis of Antibiotic and Production Genes, Mobile Genetic Elements, and Viruses in Wastewater Treatment Bioreactors

Microbial communities play a critical role in wastewater treatment processes by aiding in transformations of nutrients and other chemicals in wastewater, therefore reducing the impact of municipal and industrial discharges to the environment. Bacteria in wastewater treatment systems are also known to harbor genetic pollutants such as antibiotic resistance genes (ARGs) which can be transferred between bacteria. These ARGs may pose significant threats to public health and can pass through wastewater treatment plants (WWTPs) then ultimately migrate into lakes and rivers through release of effluent. My research focuses on understanding composition and fate of these genetic pollutants throughout wastewater treatment bioprocesses, as well on viral composition of wastewater. This involves application of a wide range of shotgun metagenomics and bioinformatics tools to investigate abundance, mobilization, and spatial distribution of genes in WWTP bioreactors. Using these techniques, we showed that ARG relative abundance in two full-scale municipal WWTPs declined by over 90% between influent and effluent, demonstrating robust removal in conventional suspended growth and biofilm-based bioprocesses. However, ARGs that were released to a receiving water body (Lake Michigan) were much more likely to be associated with markers for mobile genetic elements than those in raw influent, indicating a potential for horizontal gene transfer in natural environments. Our results also revealed a diverse viral community associated with bacterial taxa in this system. In a pilot-scale hospital wastewater treatment and water reuse system in Israel, ARG removal efficiency was significantly lower. In all of the WWTPs studied, ARGs corresponding to antibiotic classes considered to be critically important in clinical settings were identified. Bacteria hosting viruses and bacteria harboring ARGs were found to be more taxonomically similar to one another than to total bacterial populations in hospital wastewater. Finally, I investigated microscale spatial stratification of ARGs in mixed culture biofilms similar to those commonly used in wastewater treatment biofilm reactors. Several targeted ARGs and a gene commonly associated with ARG transfer between bacteria were found to have greatest relative abundances in top layers of biofilms which are most likely to detach and move downstream throughout treatment processes and ultimately into effluent. Overall, my work shows that both ARGs and viruses are diverse and abundant throughout different types of wastewater treatment systems and suggests that ARGs exhibit significant mobilization in WWTPs.

Morgan Petrovich is a fifth year PhD student in the Wells Group in the Department of Civil and Environmental Engineering at Northwestern University. Her research focuses on genetic pollutants and microbial community structure in wastewater treatment systems. She graduated from UC Berkeley with a B.A. in Landscape Architecture and Environmental Planning, and received her M.S. in Civil and Environmental Engineering from Northwestern University.

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