Madeleine Joule

Madeleine Joule

Biography

Madeleine Joule is a rising junior from Colorado State University, pursuing a B.S in
Chemical and Biological Engineering with a minor in Biomedical Engineering. Driven by
a fascination with consumer biotechnology and sustainable production, she has dedicated
her undergraduate career to exploring how biological systems can be engineered to produce
industrially relevant compounds. At her home institution, Madeleine works in the Analytical
Resources Core (ARC), where she specializes in full-service MALDI Mass Spectrometry.
She also assists with research in the School of Biomedical and Chemical Engineering,
focused on algal cultivation for renewable fuel and chemical production. These experiences
led her to MSRP, where she conducted metabolic engineering research on E. coli in the
Prather Group. Following graduation, Madeleine intends to pursue a PhD in Chemical or
Biological Engineering, with the ultimate goal of leading efforts toward a sustainable future by
developing compounds and materials that benefit both consumers and the environment.

Engineering E. Coli to Improve 2-Aminophenol Bioproduction
Madeleine Joule¹, Isabella Bowland², Kristala L. Jones Prather²
¹School of Biomedical and Chemical Engineering, Colorado State University
²Department of Chemical Engineering, Massachusetts Institute of Technology

By modifying or extending existing enzymatic pathways in microbes, metabolic engineering
enables cells to convert renewable biomass into products like pharmaceuticals or industrial
chemicals—providing a sustainable alternative to typical petrochemical-based production.
However, attempting to produce specific molecules at high concentrations can trigger cellular
toxicity through the accumulation of toxic byproducts. Such is the case during biosynthesis
of 2-aminophenol (2-AP) in Escherichia coli, which is achieved through enzymatic
transformation of the naturally occurring metabolite anthranilate by a promiscuous salicylate
1-hydroxylase (SALH). SALH activity results in excess hydrogen peroxide (H2O2), which is
toxic to the cell. With the goal of preserving cell viability and maximizing product yield, our
work aims to decrease toxicity of the byproduct H2O2 by increasing expression of Catalase
HPII (KatE), an endogenous enzyme that decomposes H2O2 into oxygen and water. We
constructed and optimized a plasmid-based system for KatE overexpression in the E. coli
2-AP production strain, evaluating the enzyme’s synthesis via gel electrophoresis. We ran
fermentation trials, assessing the protein’s effect on growth, H2O2 levels, and relative product
yield through spectrophotometry, Amplex Red assays, and HPLC, respectively. Our findings
are valuable for increasing 2-AP production in E. coli, which is essential to the process’
commercial viability.