Kaeley Elizabeth Bush, Alyssa M. Dabrowski


This project reflects research conducted as part of a course project designed to give students experience in the research process. Course: BIO 421 P1



Download Project (888 KB)


Listeria monocytogenes is a foodborne pathogen that can survive and cause infections in the human gastrointestinal tract. In susceptible populations, such as those immunocompromised, L. monocytogenes is able to cross the intestinal barrier and cause diseases such as meningitis that are much higher in mortality. During L. monocytogenes transit through the GI tract, it is exposed to the mucosal barrier rich with mucus and antimicrobial peptides (AMPs)--two major innate defense mechanisms against foreign pathogens. Moreover, the endogenous microbes produce large quantities of fermentation acids that also assist in reducing pathogen colonization. In this study, we examined the effects of mucus and propionate, one of the major fermentation acids found in the human GI lumen, on the susceptibility of L. monocytogenes to AMPs. Using nisin as a model AMP, we found that propionate and mucin alone increased the susceptibility of L. monocytogenes to nisin. With the exception of the L. monocytogenes ΔsigB mutant, in which propionate alone decreased susceptibility to nisin. We found that propionate and mucin together seemed to have no effect on the susceptibility of L. monocytogenes to nisin. From our results we also determined that anaerobic growth only increased L. monocytogenes susceptibility to nisin in the ΔsigB mutant. Further research is to be done with the human antimicrobial peptide LL-37 to see if similar results are found.

Publication Date


Project Designation

Course Project

Primary Advisor

Yvonne Y. Sun

Primary Advisor's Department



Stander Symposium project, College of Arts and Sciences

Testing the Effects of Mucin and Nisin on the Susceptibility of Listeria monocytogenes to Antimicrobial Peptides