|LU, ZHONGJING - Kennesaw State University
|MARCHANT, JOHN - Kennesaw State University
|THOMPSON, SAMANTHA - Kennesaw State University
|MELGAREJO, HENRY - Kennesaw State University
|IGNATOVA, DZHULIVA - Kennesaw State University
|KOPIC, SANDRA - Kennesaw State University
|DAMAJ, RANA - Kennesaw State University
|PARAMO, RODRIGO - Kennesaw State University
|REED, ASHLEY - Kennesaw State University
|KATHARIOU, SOPHIA - North Carolina State University
Submitted to: Frontiers in Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/2/2022
Publication Date: 7/5/2022
Citation: Lu, Z., Marchant, J., Thompson, S., Melgarejo, H., Ignatova, D., Kopic, S., Damaj, R., Paramo, R., Reed, A., Breidt, F., Kathariou, S. 2022. Bacteriophages isolated from turkeys infecting diverse Salmonella serovars. Frontiers in Microbiology. 13:933751. https://doi.org/10.3389/fmicb.2022.933751.
Interpretive Summary: Viruses that attack only selected bacteria, but don’t infect other organisms or humans, were isolated from turkey fecal material and gut contents. Six of these viruses were examined to determine the range of different bacteria they would attack, primarily focused on disease causing Salmonella strains common to poultry. These Salmonella do cause disease in humans. The viruses were examined to determine the rate at which they grow while infecting 14 different Salmonella strains. The physical protein structure of the viruses and viral DNA was examined and showed how related the viral strains were. The different Salmonella hosts the viruses would attack showed which viruses were good candidates for Salmonella control strategies. Characterization of these viruses may help with the development of methods for reducing the problem of disease-causing Salmonella on poultry without introducing antibiotics.
Technical Abstract: Salmonella is one of the leading causes of foodborne illnesses worldwide. The rapid emergence of multidrug-resistant Salmonella strains has increased global concern for salmonellosis. Recent studies have shown that bacteriophages (phages) are novel and the most promising antibacterial agents for biocontrol in foods because phages specifically kill target bacteria without affecting other bacteria, do not alter organoleptic properties or nutritional quality of foods, and are safe and environmentally friendly. Due to the vast variation in Salmonella serotypes, large numbers of different and highly virulent Salmonella phages with broad host ranges are needed. This study isolated 14 Salmonella phages from turkey fecal and cecal samples. Six phages (phi205, phi206, phi207, phiEnt, phiMont, and phi13314) were selected for characterization. These phages were from all three families in the Caudovirales order. Sodium dodecyl sulfatepolyacrylamide gel electrophoresis (SDS-PAGE) revealed that each phage had a unique structural protein profile. Each phage had a distinct host range. phi207 and phiEnt are both siphophages. They shared eight hosts, including seven different Salmonella serovars and one Shigella sonnei strain. These two phages showed different restriction banding patterns generated through EcoRI or HindIII digestion, but shared three bands from EcoRI digestion. phiEnt displayed the broadest and very unusual host range infecting 11 Salmonella strains from nine serovars and three Shigella strains from two species, and thus was further characterized. The one-step growth curve revealed that phiEnt had a short latent period (10 min) and relatively large burst size (100 PFU/infected cell). phiEnt and its host showed better thermal stabilities in tryptic soy broth than in saline at 63 or 72°C. In the model food system (cucumber juice or beef broth), phiEnt infection [regardless of the multiplicity of infections (MOIs) of 1, 10, and 100] resulted in more than 5-log10 reduction in Salmonella concentration within 4 or 5 h. Such high lytic activity combined with its remarkably broad and unusual host range and good thermal stability suggested that phiEnt is a novel Salmonella phage with great potential to be used as an effective biocontrol agent against diverse Salmonella serovars in foods.