Buchtel College of Arts and Sciences (BCAS)

Date of Last Revision

2021-09-10 12:59:11


Chemistry - Biochemistry

Honors Course

3150 497 Honors Project in Chemistry

Number of Credits


Degree Name

Bachelor of Science

Date of Expected Graduation

Fall 2019


Antibiotic-resistant bacteria present an obstacle for physicians and researchers. Over 35,000 people die annually in the U.S. from antibiotic-resistant infections each year. New antibiotics are being developed and studied, and natural products are screened to find potential new antibiotics. In this study, four polymer antibiotics with polyester backbones and peptide functional groups were studied with Escherichia coli and Staphylococcus aureus to determine the polymers’ efficacies on the different bacteria and compare the polymers to each other. Timed fluorescence microscopy experiments were performed to determine how long it takes the antibiotics to compromise the membrane integrity of fluorescently-labelled E. coli. The four polymers (designated 115B, 75A, 68B and 81C) compromised cell membranes with average times of 0.59, 2.28, 2.11 and 3.07 minutes, respectively. Faster-acting polymers were more positively charged with a higher percentage of basic side chains. Polymer 115B was 100% functionalized with positive amino acids, polymers 68B and 75A were 50% functionalized with positive amino acids, and polymer 81C was 25% functionalized with positive amino acids. MIC assays revealed that the higher molecular-weight polymers 115B and 75A had minimal inhibitory concentrations of 32 µg/mL, and the lower molecular-weight polymers 81C and 68B had minimal inhibitory concentrations of 128 µg/mL. Observations of the interaction between a labelled polymer and E. coli cells showed that the polymer appears to surround the cells at a high concentration before entering the cells. Timed fluorescence microscopy of one polymer with S. aureus also demonstrated that the polymer is effective against Gram-positive pathogens. Overall, polymer 115B was the most effective, followed by 75A, 68B, and 81C.

Research Sponsor

Dr. Michael Konopka

First Reader

Dr. Leah Shriver

Second Reader

Dr. Sailaja Paruchuri

Honors Faculty Advisor

Dr. Claire Tessier


The proposal was previously submitted and approved by the Williams Honors College.



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