The Impact of Genetic Manipulation on the Virulence of Listeria monocytogenes Strains

Haley Johnson, Phillip Brown, Dr. Sophia Kathariou, Department of Food, Bioprocessing and Nutrition Sciences, North Carolina State University, 400 Dan Allen Drive, Raleigh NC 27606

As a foodborne bacterial pathogen, Listeria monocytogenes can cause listeriosis in animal and human populations, resulting in major economic loss and even death. Common symptoms of listeriosis include diarrhea and a fever, while specific high risk populations like pregnant women experience more severe symptoms. Animals that contract this disease exhibit some of these same symptoms along with the ability to pass listeriosis to humans through human consumption of  contaminated dairy or meat products. L. monocytogenes can transfer among a variety of hosts including animals, humans, soil, water, and inanimate objects like stainless steel surfaces. This ease of transferability and life span on or inside these hosts makes this bacteria readily and easily transmissible. Genetic factors that control virulence in this bacteria are not well understood, nor are the impacts of genetic manipulation on those factors. This study uses the larvae of the greater wax moth Galleria mellonella as a model to investigate the virulence rates of different mutants or variations of the serotype 4b WS1  L. monocytogenes strain. The parental WS1 strain was compared to eleven mutant strains that had an altered genome due to the random addition of a transposon. The eleven different WS1 mutants were not able to produce the exact same enzymes, proteins, etc. as the parent strain because of the interruption in the genome from the transposon. The mutants that were tested also had altered inhibition, meaning they were able to outcompete other bacterial cells more or less than the parental strain. After running multiple trials two mutant strains were identified as having decreased virulence levels in comparison to the parental WS1 WT strain. One of these mutant strains had decreased inhibition in comparison to the parental strain while the other had increased inhibition. 

Additional Abstract Information

Presenter: Haley Johnson

Institution: North Carolina State University

Type: Poster

Subject: Microbiology

Status: Approved

Time and Location

Session: Poster 8
Date/Time: Tue 5:00pm-6:00pm
Session Number: 5648