Bacteriophage as a biocontrol tool for foodborne pathogens.
Degree GrantorUniversity of Canterbury
Degree NameMaster of Science
Despite the widespread use of interventions such as chemical sanitizers, UV light, heat (pasteurisation) and high pressure to improve food safety, incidences of foodborne disease continue to increase worldwide, prompting investigation into alternative controls. One such alternative is the use of bacteriophage (phages) for biocontrol of foodborne pathogens. As part of this research three E. coli phages and two Listeria phages were isolated, characterised and applied to investigate their biocontrol potential. Phages were first characterised by host range analysis, transmission electron microscopy and adsorption assays. These results suggested that two E.coli phages are members of the Myoviridae family, and the other is a member of the Podoviridae family, all three phages have a limited host range and are fast adsorbing. Whereas, the Listeria phage CTLLm3 is a member of the Siphoviridae family, has a broad host range and is fast adsorbing. As the E. coli phage AAPEc6 and the Listeria phage CTLLm3 showed biocontrol potential they were further investigated through kinetic and applied experiments on meats and biofilms respectively. The results of the kinetic experiments suggested that AAPEc6 was stable from pH 3-7 and a temperature range of -20°C to 50°C, similarly, CTLLm3 was stable from pH 5-7 and at a temperature range of -20°C to 40°C. Both phages showed optimal host lysis between 30°C and 40°C and at MOI values of 10 and 100. The application of AAPEc6 onto meat samples contaminated with E. coli resulted in a significant reduction in bacterial numbers, meanwhile the application of CTLLm3 onto Listeria biofilms significantly reduced biofilm mass. The results of these experiments will contribute towards our understanding of phage application as a biocontrol tool against foodborne pathogens.