Theses and Dissertations

Issuing Body

Mississippi State University


Nannapaneni, Ramakrishna

Committee Member

Cheng, Wen-Hsing

Committee Member

Zhang, Li

Date of Degree


Document Type

Graduate Thesis - Campus Access Only


Food Science and Technology

Degree Name

Master of Science (M.S.)


College of Agriculture and Life Sciences


Department of Food Science, Nutrition and Health Promotion


Listeria monocytogenes is one of the toughest challenges the food industry is facing today. While quaternary ammonium compounds (QAC) are typically applied at very high concentrations to kill L. monocytogenes, there are some factors that can cause its reduced efficacy in the food processing environment. Sublethal concentrations of stagnated QAC have been found both in processing plants and in waste waters released to the environment. Therefore, the purpose of this study was to investigate the ability of two L. monocytogenes strains, Bug600 (serotype 1/2a) and ScottA (serotype 4b) to persist in lethal and sublethal concentrations of first generation QAC (benzalkonium chloride, BAC) and second generation QAC (Ster-BAC), and if these strains would regrow when conditions had improved. Using BAC or Ster-BAC concentrations that mimic those found occurring in some environments, we determined L. monocytogenes survival, persistence, and recovery in high/low nutrient conditions, and also isolated two distinct morphotypes.