Bacteriophages PECP14, PECP20, and their endolysins as effective biocontrol agents for Escherichia coli O157:H7 and other foodborne pathogens

Abstract

Escherichia coli O157:H7 is a notorious foodborne pathogen known to cause severe illnesses such as hemolytic colitis and hemolytic uremic syndrome, with fresh produce consumption being implicated in recent outbreaks. The inappropriate use of antimicrobials to combat pathogens has led to the emergence and rapid dissemination of antimicrobial-resistant microorganisms including pathogenic E. coli, presenting a significant risk to humans. Here, we isolated two E. coli O157:H7 infecting bacteriophages, PECP14 and PECP20, from irrigation water and city sewage, respectively, as alternatives to antimicrobials. Both phages were stable for at least 16 h in a broad range of pH (pH 3–11) and temperature (4–40 °C) conditions and have a double-stranded DNA chromosome. PECP14 and PECP20, classified under the Epseptimavirus and Mosigvirus genera, respectively, exhibit specificity in targeting different host receptors, BtuB protein and lipopolysaccharide. Interestingly, these phages demonstrate the ability to infect not only E. coli O157:H7 but also other foodborne enteric pathogens like Shigella sonnei and S. flexneri. Upon mixing phages with their respective host bacteria, rapid adsorption (at least 68 % adsorption within 10 min) and substantial bacterial lysis were observed. The efficacy of phage treatment was further validated through the reduction of E. coli O157:H7 on radish sprouts. Moreover, purified endolysins, LysPECP14 and LysPECP20, derived from each phage exhibited remarkable bacteriolytic activity against E. coli O157:H7 cells pretreated with EDTA. In particular, the activity of LysPECP20 was also noticeable against Listeria monocytogenes and Bacillus cereus, suggesting its potential for broader antimicrobial applications in food industry. The combined results showed that the phages PECP14, PECP20, and their endolysins could be used for biological control of E. coli O157:H7 in various circumstances, from production, harvesting, and storage stages to processing and distribution steps of agricultural products. © 2023 Elsevier B.V.