Effect of heat-assisted pulsed electric fields and bacteriophage on enterohemorrhagic Escherichia coli O157:H7.
Pulsed electric fields (PEF), heat-assisted PEF (H-PEF), and virulent bacteriophage (VP) are non-thermal techniques for pathogen inactivation in liquids that were investigated individually, and in combination (PEF/VP, H-PEF/VP) to control enterohemorrhagic Escherichia coli (EHEC) O157:H7 in Luria-Bertani broth (LBB) and Ringer's solution (RS). Treated cells were subsequently incubated at refrigeration (4°C) and temperature-abuse conditions (12°C) for 5 days. When EHEC cells grown in LBB were subjected to non-thermal processing and subsequently stored at 12°C for 5 days, reductions in count of between 0.1 and 0.6 log cycles were observed and following storage at 4°C the decrease in counts varied between 0.2 and 1.1 log10 . For bacteria cells suspended in RS values ranged from 0.1 to ≥3.9 log cycles at both storage temperatures. The most effective treatments were H-PEF and H-PEF/VP, both producing a >3.4 log cycle reduction of cells suspended in non-nutrient RS. Analysis of EHEC recovery on selective and non-selective media indicated no occurrence of sub-lethal damage for VP, PEF/VP, and H-PEF/VP-treated cells. The findings indicate that combining PEF and lytic phage may represent a suitable alternative to conventional fluid decontamination following further process optimization.
Dept. of Food Science, Canadian Research Inst. for Food Safety, University of Guelph, Guelph, ON, Canada, N1G 2W1; Dept. of Food Science, Cornell University, Ithaca, NY, 14853.
Markus
M
Walkling-Ribeiro
Hany
H
Anany
Mansel W
MW
Griffiths
D001432:Bacteriology / Q000295:instrumentation; D001435:Bacteriophages / Q000472:pathogenicity*; D015169:Colony Count, Microbial; D004560:Electricity; D004867:Equipment Design; D019453:Escherichia coli O157 / Q000187:drug effects* / Q000528:radiation effects* / Q000648:ultrastructure / Q000821:virology*; D006358:Hot Temperature; D017053:Infection Control; D007552:Isotonic Solutions; D050296:Microbial Viability / Q000187:drug effects / Q000528:radiation effects; D000077331:Ringer's Solution
D007552:Isotonic Solutions; D000077331:Ringer's Solution
H7 sub-lethal cell injury; Luria-Bertani broth; Ringer's solution; high voltage PEF processing; lytic bacteriophage