Date of Graduation

5-2024

Document Type

Thesis

Degree Name

Master of Science in Cell & Molecular Biology (MS)

Degree Level

Graduate

Department

Cell & Molecular Biology

Advisor/Mentor

Rhoads, Douglas D.

Committee Member

Alrubaye, Adnan A.

Second Committee Member

Kwon, Young Min

Keywords

Bacterial pathogens; Genomes; Poultry breeding

Abstract

Chicken embryo mortality has been attributed to bacterial infections and can lead to a decline in hatchability, posing potential losses in the broiler industry. This study aims to investigate the vertical transmission of specific bacterial pathogens from breeder hens to subsequent broiler flocks through MGEs and their association with host specificity. In our sampling of 360 eggs from a broiler flock, we isolated various Enterococcus species, including E. gallinarum and E. faecalis, from incubated egg yolks or aborted embryos. E. avium was found in unincubated bad yolks. Other species like Streptococcus, Lactobacillus, and Bacillus were observed but presumed to be contaminants. Due to extensive research on E. faecalis, we focused on E. gallinarum (1801, 1809, and 1812) and E. avium (1788). Our isolates were tested in four different growth media. E. gallinarum exhibited significant growth in TSBcs and BHIcs under ambient CO2 conditions, while E. avium preferred BHIcs under both 5% and ambient CO2 conditions. We assembled genomes for E. avium and E. gallinarum isolates and compared them with human, bovine, and chicken genomes in the NCBI database. Although the comparative study for E. avium was limited due to the scarcity of chicken genomes, the analysis of E. gallinarum isolates indicated evolutionary relatedness with existing genomes on NCBI database. Proteome comparison of all E. gallinarum isolates, including ours, revealed 17 genes absent in bovine isolates. Prophage analysis identified a Gram-positive phage. Further bioinformatics analysis using the Prokka-Roary-Scoary pipeline indicated the presence of enzymes involved in carbohydrate, amino acid, and DNA/RNA metabolism.

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