Action spectra in the vacuum-UV and far UV (122-300nm) for inactivation of wet and vacuum-dry spores of Streptomyces griseus and photo-reactivation.

Abstract

Inactivation and photoenzymatic repair were studied in spores of Streptomyces griseus irradiated with monochromatic UV light (half bandwidth 2 nm) in the range of 200-300 nm - in the wet state - or of 122-300 nm - in the vacuum-dry state, respectively. In vacuo, the spores are about twice as UV-resistant than under wet conditions.In the vacuum-UV, it deviates from DNA absorption, passes a minimum at 190 nm and increases sharply towards shorter wavelengths; photoreactivation is absent. It is suggested that absorption by cellular com- ponents other than DNA will become important. In the far-UV, the photoreactivable sector is higher in spores irradiated in the wet state than in those irradiated in vacuo. It is postulated that, in the vacuum-dry state, DNA photoproducts other than in cis-syn pyrimidine dimers appear to be also relevant for the lethality.