Action spectra for inactivation of dry phage T1 after monochromatic (150-254 nm) synchrotron irradiation in the presence and absence of photoreactivation and dark repair.

Dry phage T1 was irradiated with monochromatic uv radiation (150-254 nm) in vacuo. The inactivation sensitivity was highest at 150 nm. On Escherichia coli Bs-1, the phage inactivation sensitivity was two and four times higher at 150 nm than at 254 and 230 nm, respectively. Action spectra for phage inactivation on both E. coli B and Bs-1 fit the absorption spectrum of phage DNA, except around 190 nm. The host-cell- reactivable fraction for vacuum-uv radiation (below 190 nm) was smaller than that with far-uv radiation. There was almost no photoreactivation at 150 nm, in contrast to a photoreactivation sector of about 0.3 at 254 nm.