title: Antimicrobial activity of epsilon-polylysine against Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes in various food extracts.
abstract: This study compared the antimicrobial effects of epsilon-polylysine (epsilon-PL) against Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes in 6 food extracts and in broth. The food extracts (10% (w/w) in distilled water) evaluated were fat-free and whole fat milk, beef, bologna, rice, and vegetables (50:50 ratio of broccoli and cauliflower). epsilon-PL was tested at 0.005% and 0.02% (w/v) against E. coli O157:H7 and L. monocytogenes, and 0.02% and 0.04% (w/v) against S. Typhimurium. The substrates were inoculated (5 log CFU/mL) and periodically analyzed for surviving populations during storage at 12 degrees C for 6 d. In general, all 3 pathogens reached 7 to 9 log CFU/mL within 2 d in control substrates (no epsilon-PL). Immediate bactericidal effects (P < 0.05) following exposure to epsilon-PL were obtained in the rice (all pathogens) and vegetable (E. coli O157:H7 and S. Typhimurium) extracts. During storage, antimicrobial effects of epsilon-PL were more pronounced in the food extracts than in the broth medium. The greatest antimicrobial activity for all 3 pathogens was obtained in the rice and vegetable extracts, where counts were reduced (P < 0.05) to below the detection limit (0.0 log CFU/mL) by one or both epsilon-PL concentrations tested. In the other food extracts (fat-free milk, whole fat milk, beef, and bologna), both epsilon-PL concentrations tested generally resulted in lower (P < 0.05) pathogen levels at the end of storage compared to initial counts, with better bactericidal effects exerted by the higher of the 2 epsilon-PL concentrations. Additional research is needed to explore the potential antimicrobial effects of epsilon-PL in real food systems.
authors.affiliation: Center for Red Meat Safety, Dept. of Animal Sciences, Colorado State Univ., 1171 Campus Delivery, Fort Collins, CO 80523-1171, USA.
authors.forename: I
authors.initials: I
authors.lastname: Geornaras
authors.forename: Y
authors.initials: Y
authors.lastname: Yoon
authors.forename: K E
authors.initials: KE
authors.lastname: Belk
authors.forename: G C
authors.initials: GC
authors.lastname: Smith
authors.forename: J N
authors.initials: JN
authors.lastname: Sofos
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D004305:Dose-Response Relationship, Drug; D019453:Escherichia coli O157 / Q000187:drug effects* / Q000254:growth & development; D005506:Food Contamination / Q000032:analysis / Q000517:prevention & control*; D005516:Food Microbiology; D005519:Food Preservation / Q000379:methods; D006801:Humans; D008089:Listeria monocytogenes / Q000187:drug effects* / Q000254:growth & development; D011107:Polylysine / Q000494:pharmacology*; D012486:Salmonella typhimurium / Q000187:drug effects* / Q000254:growth & development; D013696:Temperature; D013997:Time Factors
chemical_list: D000900:Anti-Bacterial Agents; D011107:Polylysine