3. Sensitivity to Freezing Storage of Pseudomonas aeruginosa Phage 24(IFO 20050)(Papers presented at the 35th Annual Meeting, April, 1989, Tokyo)

Abstract

Freezing storage at -20℃ was applied for eight bacteriophage strains for Pseudomonas aeruginosa, and their viability was examined. Of eight strains, seven were stably preserved both in the presence and absence of glycerol. An osmosensitive phage 24 (IFO 20050) was found to be sensitive to the freezing storage in the presence of 5 and 10% glycerol. Addition of sucrose or glucose made the same degree of loss in titer as that of glycerol. T-even phages of Escherichia coli, which are known to be osmosensitive, were also sensitive to the freezing storage in the presence of glycerol. When the phage lysate supplemented with 5% glycerol was cooled in dry ice-ethyl alcohol and stored at -80℃ for 1 week, the loss in titer was diminished. However, storage at -20℃ made remarkably the loss in titer. The unfrozen water content of the phage lysate with or without sugars was examined by DSC. In the presence of sugars that caused the remarkable loss in titer, the amount of unfrozen water increased at -20℃. On the other hand, the increasing of unfrozen water occurred at -7℃ in the absence of sugars. After storage at -20℃ for 1 week, the viability of lysate supplemented with both 5% glycerol and 1.7% methyl alcohol was 100 fold higher than that without methyl alcohol. Addition of 5% DMSO also markedly prevented the loss in titer by freezing storage at -20℃ in the presence of 5% glycerol. Freezing storage of phage 24 in the presence of glycerol caused leakage of DNA from phage particles. Those findings suggest that sugars can affect on hydrophobic domains of a protein of the phage particle and change the stereostructure of proteins, and this change can trigger off the leakage of DNA from particles.