Characterization of Salmonella ser. Enteritidis-specific bacteriophages and biocontrol strategy to reduce S. Enteritidis on egg products using bacteriophages and essential oil compounds

Abstract

Salmonella contamination of egg products is a major concern in the poultry industry. This study aimed to characterize newly isolated lytic Salmonella bacteriophages and evaluate the efficacy of Salmonella ser. Enteritidis biofilm reduction using a selected phage (CAU-SEP-3 at 100 MOI), essential oil (EO) compounds (thymol [Thy] and geraniol [Ger]) at 1 × MIC, and the combination of phage and EO compounds on food-contact materials (stainless steel [SS] and polypropylene [PP]) and quail eggs (at 4 and 25 °C). On both the coupons and eggshells, the combination treatment reduced Salmonella biofilms more effectively than either of the single treatments, and no differences in texture were detected after the combination treatment on quail eggs compared with the control. Confocal laser scanning microscopy analysis and three-dimensional imaging using COMSTAT provided visualization of biofilm reduction. Gene expression levels were compared using quantitative real-time PCR analysis, indicating that the combination treatment was the most effective in reducing the avrA, hilA, rpoH, rpoS, sefA, and spvR gene expression levels. A DNAPlotter image of CAU-SEP-3 was generated based on genome sequencing data, revealing that 35 (17.6%) proteins were predicted to be functional proteins, while 147 (82.4%) were annotated as hypothetical proteins. This study demonstrates that the combination of phage and EO compounds is potentially effective in inactivating S. Enteritidis biofilms; furthermore, it may contribute to the safety of future production and processing of eggs. © 2024 Elsevier Ltd