Synergistic action of near ultraviolet radiation and hydrogen peroxide on the killing of coliphage T7: possible role of superoxide radical

The synergistic action of near ultraviolet (NUV) radiation and hydrogen peroxide (H2O2) on bacteria and bacteriophages is that they are inactivated at doses at which the individual agents have little or no effect. Studies with the reduction of nitroblue-tetrazolium chloride and the oxidation of NADPH show that superoxide radical is generated when H2O2 is photolysed by NUV. Since T7 inactivation by NUV and H2O2 is greatly reduced in the presence of superoxide dismutase it is suggested that superoxide radical or one of its reactive products is involved in the phage inactivation. Hydroxy radical is probably not responsible for the phage inactivation since the scavengers of this radical do not protect T7 exposed to NUV and H2O2. (Auth.)