Off-campus UNL users: To download campus access dissertations, please use the following link to log into our proxy server with your NU ID and password. When you are done browsing please remember to return to this page and log out.

Non-UNL users: Please talk to your librarian about requesting this dissertation through interlibrary loan.

Examination of the Prevalence and Behaviors of Pathogenic and Spoilage Bacteria at Multiple Stages in the Meat Processing Chain

Samuel C Watson, University of Nebraska - Lincoln


As long as there is food, there will also be bacteria that are capable of compromising the quality and safety of food. This dissertation aims to study bacteria capable of spoiling meat, causing illness, or both. The literature review summarizes the understanding of several bacterial pathogens, current issues in combating those pathogens in the food supply, and how spoilage Pseudomonas behave in the meat supply. Chapter 2 explored the impact of organic acid treatments on the spoilage microbiome of raw beef during extended storage. While Pseudomonas and Yersinia were both present in significant levels, Lactococcus was determined to be the most abundant taxa throughout the shelf life of the raw beef products. These results confirmed that lactic acid does little to control the growth of lactic acid bacteria. Chapter 3 aimed to determine if two Pseudomonas isolates, which are typically considered to be aerobic bacteria, were capable of surviving in thermally processed meat products. The isolates were quickly recovered in the weeks after thermal processing and grew under vacuum in refrigerated storage over the course of 294 days. Lastly, Chapter 4 attempted to determine if troublesome Pseudomonas were able to promote the prevalence of Listeria monocytogenes in ready-to-eat meat processing environments. Three meat processors in Nebraska were sampled, and culturable isolates were categorized for biofilm production and sanitizer tolerance. Multiple Pseudomonas isolates belonging to Pseudomonas aeruginosa, Pseudomonas putida, and Pseudomonas fluorescens demonstrated the ability to form biofilms and tolerate the manufacturer recommended concentration of quaternary ammonia sanitizer. Some of these isolates were cultured alongside Listeria monocytogenes and Listeria spp.

Subject Area

Animal sciences|Microbiology|Food Science

Recommended Citation

Watson, Samuel C, "Examination of the Prevalence and Behaviors of Pathogenic and Spoilage Bacteria at Multiple Stages in the Meat Processing Chain" (2023). ETD collection for University of Nebraska-Lincoln. AAI30813897.