The effect of different media and temperature conditions for Salmonella bacteriophage preservation

This research aimed to determine the optimal media and temperature conditions for the long-term storage of bacteriophages. In this study, the viability of Salmonella phages in 50% glycerol, 10% sodium chloride-magnesium sulfate (SM) buffer, and 5% dimethyl sulfoxide (DMSO) media at room temperature, 4oC, -20oC, and -80oC for 12 months was determined. In 50% glycerol, at the end of the experiment, no significant difference was found between four temperature conditions on phage density, ranging from 6.20-6.23 log10 PFU/mL (P>0.05). Under 10% SM medium, phage preservation at room temperature provided the optimum density at 6.31 log10 PFU/mL. In addition, phages preserved in a 5% DMSO medium were of similar density values across all temperature treatments. Still, their availability after 12 month-storage (88.0-88.5%) was significantly lower (P<0.05) than that of 50% glycerol and 10% SM. Moreover, for phage lysis capacity, low temperatures (4oC, -20oC, and -80oC) were superior to room temperature used for preservation. Considering the density, lysis capacity, and practical convenience, storing phages at 4°C in a 50% Glycerol medium is recommended.