Killing and Photoreactivation of Streptomyces griseus Conidia by Vacuum-Ultraviolet and Far-Ultraviolet Radiation (1500 to 2700 A)

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Abstract
Conidia of S. griseus were irradiated in vacuum in the wave-length range 1550 to 2650 A and in aqueous suspension in the range 2000 to 2650 A. Although absorption of the radiation at short wavelengths is an important factor, it was possible to correct for this and to show by a variety of criteria that the chromophore for killing of cells in aqueous suspension is probably nucleic-acid in the wavelength region studied. The killing of dry cells, becomes inefficient and shows different kinetics at wavelengths below 2400 A, and it was not possible to identify the chromophore in this region. The photoreactivable sector is the same for wet and dry conidia at all wavelengths, being high at 2650 A but dropplng at an increasing rate with decreasing wavelength until it falls to 0 around 1700 A. This similarity in behavior suggests that the chromophore is the same in both wet and dry cells (nucleic-acid) and that the lower efficiency of killing and different kinetics at short wavelengths in dry cells reflects a difference in the efficiency of production but not in the nature or relative proportions, of the photo-products in wet and dry cells.