Comparison of Various Storage Conditions for The Stability of Escherichia coli O157:H7 Bacteriophage M8AEC16

Abstract

In this study, bacteriophage M8AEC16, which is lytic to Escherichia coli O157:H7, isolated and characterized within the scope of our previous studies, was used to determine the stability during 6 months of storage at +4°C, -20°C and -85°C using glycerol, skimmed milk powder and carrageenan as cryoprotectants. For this purpose, bacteriophage M8AEC16, was enriched with E. coli O157:H7 ATCC 43895 and then phage suspension groups were prepared by adding three different cryoprotectants (test groups) in addition to those without cryoprotectant (control). Bacteriophage suspensions were stored at 3 different storage temperatures (+4°C, -20°C and -85°C) for six mount period. During storage, phage titers were determined on double-layer LB agar by making serial dilutions of phage suspensions on the 0th day and at the end of each month. As a result of the study, it was observed that stability was maintained at all temperatures for all groups during the first two months. However, in the third and fourth months, a decrease in the counts of bacteriophages were observed at -85°C in the glycerol added group. In addition to the control group, in the fifth month, carrageenan provided the highest preservation at all temperatures. In the sixth month, +4°C glycerol provided the best preservation, while carrageenan provided the highest preservation at other temperatures compared to the other test groups. In conclusion, the most successful result was obtained at +4°C for the preservation of Escherichia coli O157:H7 phage M8AEC16 considering the cost, usefulness and effectiveness.