Characterization and genomic analysis of a broad-spectrum lytic phage vB_EcoM_SD350 and its application on raw chicken and beef meats against Avian pathogenic Escherichia coli

Abstract

Avian pathogenic Escherichia coli (APEC) leads to tremendous economic losses in the poultry industry and poses a threat to public by transmission of pathogens via food chain. Due to the increasingly problematic prevalence of antibiotic resistance among APEC, there is an urgent need to find alternative therapeutics. In this study, a novel phage, named vB_EcoM_SD350, was isolated and profiled. It had a broad lytic spectrum and was capable to lyse 64.00 % (48/75) selected Escherichia coli strains. Biological characterization showed that phage vB_EcoM_SD350 displayed adorable tolerance to pH and temperature and was able to effectively inhibit the growth of Escherichia coli SD405 and biofilm formation. The genomic analysis revealed that phage vB_EcoM_SD350 genome was a double-stranded DNA with a size of 52,757 bp and a guanine-cytosine (GC) content of 47.73 %. And ORF44 and ORF45 in phage vB_EcoM_SD350 were predicted to encode a holin and an endolysin, respectively. The results indicated that phage vB_EcoM_SD350 lysed bacteria through the holin-endolysin system, thereby releasing progeny phages. Finally, when phage vB_EcoM_SD350 was applied to chicken and beef samples stored at 4 °C, the concentration of SD405 decreased by 0.56–2.88 log CFU/g in the chicken group and by 0.43–3.98 log CFU/g in the beef group within 72 h. In summary, this study identified a new phage to effectively lyse a broad range of APEC, highlighting its potential as an antibacterial agent for biocontrol of Escherichia coli in meat products.