Graduation Year


Document Type

Open Access Senior Thesis

Degree Name

Bachelor of Arts



Reader 1

Pete Chandrangsu, PhD

Reader 2

Sarah Budischak, PhD

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Rights Information

2022 Maya D Addison


Each year over 2.8 million Americans are infected by an antibiotic resistant strain of bacteria with over 35, 000 dying as a result (CDC). The lack of development of new antibiotics has renewed interest in the antimicrobial properties of copper. Gram positive bacterium such as Bacillus subtilis produce poly-gamma-glutamic acid (γ-PGA) to sequester excess copper ions. swrA has shown to be essential for proper activation of the pgs operon by phosphorylated DegU via an unknown mechanism. This study seeks to determine the role of swrA in copper induced gamma-PGA production and if swrA and ppsB are involved in copper resistance. Copper Morphology assays were conducted with ΔswrA, GJ014, GJ015, and 3610 B. subtilis. swrA mutants did not produce γ-PGA in the presence of copper. Kirby Bauer assays were conducted with ΔswrA, ΔppsB, ΔswrAΔppsB mutants and 3610 B. subtilis to assess copper resistance There were no significant differences in the average zone of inhibition of all four strains tested. The results of this study indicate that swrA is essential for copper induced γ-PGA production. This study also points to a regulatory pleotropic role of swrA of the pgs, fla/che, and srfA operon via the deg system to allow for continued copper resistance. Further understanding the role of γ-PGA production will assist in developing future antimicrobials using copper.