[Effect of freezing modes on the survival of Escherichia coli bacteriophages]

The object of this work was to study the effect of freezing down to--196 degrees C at different cooling and warming rates on the survival of T3, T4 and phiX174 phages. Phage particles survived when T3 phage was frozen at a rate of 20-400 degrees/min and phiX174 phage at a rate of 20-45 degrees/min. The survival rate of T4 phage was highest when it was frozen at a rate of 45 degrees/min. The survival of the phages depended also on the regime of warming. The susceptibility of the phages to freezing correlated with their sensitivity to osmotic shock in NaCl and sucrose solutions.