Life Sciences Commons^™

Investigating Natural And Induced Biofilm Dispersion In Listeria Monocytogenes, Brett Boulden

Masters Theses

Dispersion is a natural part of a biofilm life cycle in many bacterial species. Dispersion occurs when bacteria revert from a stationary, sessile state to a free-swimming, planktonic state and are freed from a biofilm. Bacterial biofilms consist of proteins, polysaccharides, and extracellular DNA that together make up the extracellular polymeric substances. Surrounded by this mucus-like substance, sessile cells can be extremely difficult to eradicate as compared to the planktonic form of Listeria monocytogenes. Biofilms are robust due to increased surface adherence, inhibition of diffusion of harmful compounds, and increased genetic diversity that exists within a biofilm. As a …

Influence Of Lipoteichoic Acid On Listeria Monocytogenes Biofilm Formation And Cellular Stress, Imelda T. Brooks

Doctoral Dissertations

Lipoteichoic acid (LTA) is an important polymer on the surface of Gram-positive organisms, including the foodborne, biofilm-forming pathogen Listeria monocytogenes, and is connected to the cell membrane through a glycolipid backbone. Previous results have shown the importance of LTA in cell viability and biofilm formation. The purpose of this research is to further investigate the influence of LTA in L. monocytogenes biofilm formation and how the bacterium responds to environmental stress caused by antimicrobial exposures, and a combination of low temperature and high osmolarity. We created in frame deletion mutants along the operon lmo-2555-lmo2554-lmo2553, which have been shown …

Susceptibility Of Escherichia Coli O157:H7, Salmonella Enterica Sp., And Listeria Monocytogenes To Antimicrobial Mixed Micelle Delivery Systems, Chanelle N. Adams

Doctoral Dissertations

Within the food industry, there is an ever increasing demand to improve the quality of food and ensure safety from pathogenic/spoilage microorganisms. Globalization of the food industry in the 1990’s, in conjunction with the worldwide shipment of food created a need for the extension of shelf-life and enhanced maintenance of food quality (12). In the United States alone, the Centers for Disease Control and Prevention report that each year, roughly 1 in 6 Americans (or 48 million people) gets sick, 128,000 are hospitalized, and 3,000 die of foodborne diseases; this correlates to approximately $77.7 billion in economic loss annually (17). …

The Effect Of Curcumin (Curcuma Longa) On Biofilm Formation And Surface Proteins Of Listeria Monocytogenes, Songsirin Ruengvisesh

Masters Theses 1911 - February 2014

The food-borne pathogen Listeria monocytogenes can attach to the environmental surfaces and develop biofilm which can cause food contamination in the food industries. Sortase A and surface proteins are involved in biofilm and virulence of L. monocytogenes. Curcumin was reported to inhibit sortase A and biofilm in gram positive bacteria. The overall objective of this study was to observe the effect of curcumin (Curcuma longa) on the biofilm formation and surface proteins of L. monocytogenes.

The antibiofilm effect of curcumin against the strain LM21 (wild type) and s22-11G (sortase A defective mutant) was studied using the …

Transfer Of Listeria Monocytogenes From Stainless Steel And High Density Polethylyene To Cold Smoked Salmon And Listeria Monocytogenes Biofilm Cohesive Energy Investigation, Fujia Zhang

Masters Theses 1911 - February 2014

Listeria monocytogenes is a major concern for the food industry. It is one of the major agents causing listeriosis. The objective of the first part of this study is to evaluate the effect of hydration level on attached listeria monocytogenes on stainless steel/High density polyethylene transferred to food products. Attached cells were prepared on stainless steel/High density polyethylene. Transfer experiments were conducted from inoculated surface material slides to cold smoked salmon fillets. This experiment was repeated 6 times. The results were analyzed with an analysis of variance by SAS. The differences between the different RH% and surface conditions were not …