Physical Studies of Glycerol Protection against X-Ray Inactivation of Bacteriophage

The effect of 33% (v/v) glycerol on x-ray induced inactivation, DNA double-strand breakage, and base damage of E. coli phage λ and single-strand breakage in Ps. aeruginosa phage B3 has been investigated. The dose reduction factors are 2.4, 3.2, 1.6, and 3.1, respectively. The agreement between the dose reduction factors for DNA double- and single-strand breakages suggests (1) that both processes probably occur by similar mechanisms and (2) that the small protective effect of glycerol against x-ray inactivation of single-strand DNA phages is not due to a differential effect on single- and double-strand breakage, as proposed by Hotz. As would be predicted from earlier experiments which showed that the primary effect of anoxia + cysteine is to eliminate base damage, it was shown that survival curves for DNA breakage are identical to those for phage inactivation by x-irradiation under conditions of anoxia + cysteine both in the presence and absence of glycerol.