The Preparation of a Polyvalent Dysentery Bacteriophage in a Dry and Stable Form

Abstract

The loss of lytic activity following lyophili- zation of a sensitive anti-Shiga dysentery phage was not due to the freezing involved in the drying procedure. Maintenance of the drying vessel at[long dash]18[degree] C throughout the lyophilization period did not decrease the instability of the phage. No pH value in the range 2.94 to 9.51 was more favorable for maintenance of the lytic activity of the sensitive phage than that of the unadjusted lysate, viz., 7.18. Additions to the phage lysate of NaCl in amts. varying from 0.18% to 1.46% afforded no "protection" against inactivation by the drying procedure, but caused no marked increase in sensitivity. Lyophilization of phage adsorbed on alumina gel did not maintain activity. Meat extract, gelatin, dried egg albumen, peptone, gastric mucin, human serum and plasma, added to the phage lysates, did not provide consistent and satisfactory "protection." Lactose, soluble starch, glycogen, pectin, agar, gum acacia and methyl cellosolve were not effective stabilizers and some were additionally inactivating. 1% glycogen did not affect the fluid phage but caused complete loss of lytic activity on lyophilization. Raw egg white prevented glycogen inactivation. Raw egg white, Difco yeast extract, Difco brain-heart infusion, fresh aqueous extracts of heart muscle, liver, pancreas, brain, thymus and kidney stabilized the sensitive phage during lyophilization; brain, thymus and kidney were most effective. When raw egg yolk was added to the sensitive phage lysate good "protection" resulted. Crude lecithin freshly extracted from raw egg yolk was equivalent to egg yolk in effect. Cholesterol was an indifferent addition substance.