Abstract
Escherichia coli O157:H7 is a global concern that causes serious diseases, such as hemolytic uremic syndrome and bloody diarrhea. To control E. coli O157:H7 in food, a novel siphophage, BECP10, that targets the O157 serotype was isolated and characterized. Unlike other E. coli phages, BECP10 can only infect E. coli O157 strains, and thus, did not infect other strains. The 48 kbp genome of BECP10 contained 76 open reading frames (ORFs), including 33 putative functional ORFs. The phage did not contain lysogeny-related modules or toxin-associated genes, suggesting that the phage might be strictly lytic. The tail spike protein (TSP) sequence had very low homology with the reported T1-like phages, indicating that TSP might be related to this unique host spectrum. The specific O-antigen residue of E. coli O157:H7 may be a key factor for phage infection by adsorption and receptor identification. The phage exhibited strong antibacterial activity against E. coli O157:H7 over a broad pH range and showed little development of phage-insensitive mutants. The phage sustained viability on the burger patties and reduced E. coli O157:H7 to a non-detectable level without the emergence of resistant cells at low temperatures for five days. Therefore, phage BECP10 might be a good biocontrol agent for E. coli O157:H7-contaminated food matrices.
Highlights
Heat processes can efficiently remove E. coli O157:H7; because these processes cannot be applied to heat-sensitive foods, alternatives such as chlorine gas, essential oil, and organic acid have been extensively studied and proposed [10]
The efficiency of plating (EOP) was determined as the ratio of the number of plaques appearing on the lawn of a test strain to the number of plaques on the reference strain, E. coli NCTC 12079
BECP10 formed a significant halo zone around the plaque (Figure 1A). This halo is known to be formed when the cell wall components of bacteria are degraded by depolymerase in the phage, and these properties cause irreversible damage to Viruses 2021, 13, x FOR PEER REVIEWthe cell walls of target bacteria [34]
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Most foodborne pathogens are problematic; enterohemorrhagic Escherichia coli (EHEC) is considered a fatal hazard in the food industry [5]. Heat processes can efficiently remove E. coli O157:H7; because these processes cannot be applied to heat-sensitive foods, alternatives such as chlorine gas, essential oil, and organic acid have been extensively studied and proposed [10]. These alternatives are known to be very effective disinfectants for controlling. Bacteriophages (phages) are bactericidal viruses that can only target specific host bacteria and have been proposed as an attractive strategy to control foodborne pathogens [13]. BECP10 was found to efficiently reduce E. coli O157:H7 in burger patties without the emergence of resistant mutants
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