Investigating the synergistic effects of Acid-Producing Bacteria as Natural Antimicrobials Against Salmonella Serovars

This thesis delves into pathogen control within the meat sector, specifically focusing on the beef industry and addressing the persistent challenges posed by microbial contamination despite current intervention strategies. The literature review highlights the critical need for effective solutions, with a focus on acid-producing bacteria (APB) as a promising alternative for both pre-harvest and post-harvest interventions. By producing organic acids, APBs create hostile environments for pathogens, including Salmonella, which remains a significant public health threat due to its survival capabilities and pathogenicity. Study I investigates the antimicrobial potential of 15 different APB strains against various Salmonella serovars. The study demonstrates that these bacteria, particularly Propionibacterium strains, significantly lower the pH of their environment and exhibit strong inhibitory effects on Salmonella. S. Enteritidis was the most inhibited, while S. Heidelberg was the least inhibited. The findings suggest that APBs are more effective than organic acids alone in enhancing food safety by inhibiting pathogen proliferation. Building on these insights, Study II explores the synergistic effects of multi-strain APB combinations against seven Salmonella serovars. This study reveals that these combinations produce higher concentrations of organic acids and demonstrate strong antimicrobial activity. Particularly, the combination of two Propionibacterium strains, one Lactobacillus strain, and one Bifidobacterium strain was the most effective, achieving significant inhibition of several Salmonella serovars. This indicates a promising sustainable strategy for reducing Salmonella contamination in food production environments, further enhancing the understanding of how combined APB strains can be more effective than individual strains. iv Texas Tech University, Maria Camila Duarte Villanueva, December, 2024 Overall, this research underscores the potential of APB in creating sustainable and effective pathogen control strategies in the meat industry, enhancing food safety from farm to fork. These comprehensive studies provide valuable insights into the application of APB for mitigating risks associated with foodborne pathogens, particularly Salmonella, and contribute to the development of more integrated approaches to food safety. This holistic approach presents a significant step forward in improving food safety protocols and protecting public health.