Honors Theses


Yvonne Sun, Ph.D.



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Honors Thesis


Bacterial infections that can no longer be treated by antibiotics because of bacterial mutations cause many infections and deaths each year. My research conducted aims to study how membrane fatty acid composition can affect membrane susceptibility to antibiotics. Listeria monocytogenes, a gram-negative facultative anaerobe, is the bacterium that I am testing. Listeria has 80-90% branched-chain fatty acids (BCFAs) which allow membrane fluidity and sufficient protection against invaders. When Listeria is grown in the presence of butyrate, the BCFAs become straight-chain fatty acids (SCFAs) and make the once fluid membrane more rigid. This allows for easier antibiotic penetration of the phospholipid bilayer which lets the antibiotics affect cellular processes. By changing concentrations of butyrate I can calculate the minimum inhibitory and bactericidal concentrations of butyrate. Oxygen consumption rate will be calculated to measure the effect of butyrate. The more oxygen consumed, the more electron transport chain activity, which takes place in the cell membrane, there is. Therefore, by comparing oxygen consumption rates normalized by optical density of bacteria with and without butyrate present, we determined the effects of butyrate on cell membrane functionality. This data was used to determine the effectiveness of various antibiotics with and without butyrate in order to conclude whether antibiotic resistance can be combated by altering the composition of the bacteria.

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Undergraduate research



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