Impacts of Salmonella Translocation on Table Egg Microbiome Under Hatching Conditions

Salmonella poses a significant concern for poultry breeders, as this pathogen can become associated with the embryo and persist throughout the life of the bird. The primary objective of this study was to establish the rate at which Salmonella on the exterior surface of the eggshell translocates through the shell and determine the microbial population shifts associated with Salmonella presence under hatching conditions, using table eggs as a model for fertilized eggs. Genomic DNA was extracted prior to a custom dual-indexed primer library preparation and sequencing with Illumina MiSeq. Data generated from sequencing was analyzed using QIIME2 2024.10, with comparisons for alpha and beta diversity being assessed with Kruskal-Wallis and ANOSIM, respectively. Possible interactions between location on the egg and time were determined using ANOVA and ADONIS methods. It was determined that Salmonella can disrupt the evenness, richness, and relative abundance of the microbial community on primarily the outside of the eggshell, but also the inside of the eggshell as well as the egg contents. As seen with ANCOM-BC, many more taxa are depleted on the outside of the eggshell in the Salmonella group compared to the uninoculated group, suggesting Salmonella can outcompete members of the existing microbiota for colonization. Core microbiome taxa revealed an organism belonging to the order of Enterobacterales present in all sampling locations in the Salmonella group. Therefore, Salmonella has been shown to impact the egg microbiome and has the potential to invade all areas of the egg.