Bio-Control of Salmonella Enteritidis in Foods Using Bacteriophages

Abstract

Two lytic phages, vB_SenM-PA13076 (PA13076) and vB_SenM-PC2184 (PC2184), were isolated from chicken sewage and characterized with host strains Salmonella Enteritidis (SE) ATCC13076 and CVCC2184, respectively. Transmission electron microscopy revealed that they belonged to the family Myoviridae. The lytic abilities of these two phages in liquid culture showed 104 multiplicity of infection (MOI) was the best in inhibiting bacteria, with PC2184 exhibiting more activity than PA13076. The two phages exhibited broad host range within the genus Salmonella. Phage PA13076 and PC2184 had a lytic effect on 222 (71.4%) and 298 (95.8%) of the 311 epidemic Salmonella isolates, respectively. We tested the effectiveness of phage PA13076 and PC2184 as well as a cocktail combination of both in three different foods (chicken breast, pasteurized whole milk and Chinese cabbage) contaminated with SE. Samples were spiked with 1 × 104 CFU individual SE or a mixture of strains (ATCC13076 and CVCC2184), then treated with 1 × 108 PFU individual phage or a two phage cocktail, and incubated at 4 °C or 25 °C for 5 h. In general, the inhibitory effect of phage and phage cocktail was better at 4 °C than that at 25 °C, whereas the opposite result was observed in Chinese cabbage, and phage cocktail was better than either single phage. A significant reduction in bacterial numbers (1.5–4 log CFU/sample, p < 0.05) was observed in all tested foods. The two phages on the three food samples were relatively stable, especially at 4 °C, with the phages exhibiting the greatest stability in milk. Our research shows that our phages have potential effectiveness as a bio-control agent of Salmonella in foods.

Bacteriophages and their applications

“…In some cases, PEG precipitation is applied in the concentration of phage particles procedure. It was used to prepare high titers of Salmonella-specific phages by Bao et al (2011), Wong et al (2014, Bao et al (2015) and other researchers.…”

“…A novel cold-active bacteriophage VNPH-1 specific for Aeromonas sobria was comparatively stable at pH 5.0 to 10.0 and the optimum phage infectivity occurred at pH 9.0 (Ji et al, 2015). Similarly, Salmonella-infecting bacteriophages REVIEW include phage PA13076 (Bao et al, 2015), phage SE2 (Tiwari et al, 2013), phage PSPu-95 and phage PSPu-4-116 (Bao et al, 2011), were relatively stable within the pH range of 4.0 to 10.0. However, recent studies by Hu et al (2016) on thirteen lytic distinct Pseudomonas bacteriophages reported that all phages were active over a very narrow pH range, from 6.0 to 7.0.…”

“…Most bacteriophages act optimally at temperatures between 30 -50˚C (Bao et al, 2015;Ji et al, 2015;Zhang et al, 2015). Bacteriophages were also found to be active over the temperature range of 4-50˚C (Jun et al, 2013) and 4-60˚C (Easwaran et al, 2015) for Shigella flexneri phage pSf-1 and Escherichia coli phage Sw1, respectively.…”

“…Interventions using bacteriophages can be performed at different or even multiple points in the food processing facility or throughout the food chain to enhance the control process. It has been suggested that Salmonella bacteriophages can be added by dipping or spraying or as a liquid to different food matrices (Spricigo et al, 2013;Zinno et al, 2014;Bao et al, 2015;Sukumaran et al, 2015).…”

Genome Sequence of Bacteriophage GG32, Which Can Infect both Salmonella enterica Serovar Typhimurium and Escherichia coli O157:H7

“…Typhimurium) and Escherichia coli ( E. coli ) O157:H7 are major food-borne pathogens causing serious diseases (1, 2). Bacteriophages have been used to bio-control agents in a variety of foods (3, 4). We report a new virulent bacteriophage GG32 isolated from the Guem River in the Republic of Korea.…”