Killing of bacteriophage Tl by irradiation in a dry state with synchrotron orbital radiation, monochromatic 122 nm and 254 nm light

Bacteriophage Tl dried in a vacuum was irradiated with synchrotron orbital radiation (SOR) having a broad spectrum above 115 nm. For comparison, the phage was also irradiated with monochromatic 122 nm and 254 nm light in a dry state. When the phage was irradiated with SOR in a vacuum (above 115 nm), the fraction of host cell reactivation was larger than that irradiated with monochromatic 122 nm light but smaller than that irradiated with SOR under atmospheric conditions (light with wavelengths shorter than 190 nm being cut) or with 254 nm light. Photoreactivation of the phage irradiated with SOR was negligible. For the phage irradiated with 122 nm, no photoreactivation was observed. It may be concluded that the major photoproduct produced in dried phages by vacuum-uv light is different from the pyrimidine dimers of cyclobutane type which has been known to occur in phages irradiated with 254 nm light in a wet state. (author)