Attempts to freeze some bacteriophages to ultralow temperatures.

A variety of bacteriophages specific for different hosts, including Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa, Serratia marcescens, Shigella dysenteriae, Staphylococcus aureus, and Vibrio comma, were frozen at a controlled rate to liquid nitrogen temperatures, and then quick-thawed. Glycerol (10%) was used as a protective additive. Quantitative determinations showed from 10% to virtually 100% recovery in the various cases. Host specificity, plaque morphology, and, in one case, rate of inactivation of phage by homologous antiserum remained unchanged.