Ultraviolet inactivation and photoreactivation of the cholera phage 'kappa'.

The lysogenic cholera phage, 'Kappa' is some ten to twenty folds more resistant to UV (254 nm) than are most of the T. phages of E. coli, or the cholera phage PL 163/10, or the host V. cholerae strain H218 Smr, the 37% (D37) and 10% (D10) survival doses being 255.8 J/m2 and 633.6 J/m2 respectively. The UV-irradiated 'Kappa' phages could be photoreactivated in the host V. cholerae strain H218 Smr to a maximum extent of 40%. The removal of the number of lethal hits per phage by the survival-enhancement treatment (photoreactivation) with time followed an exponential relation, the constant probability of removal of lethal hit per unit time being 2.8 x 10(-2)min-1. The UV-irradiated phages could also be Weigle reactivated in the host strain H218 Smr by a small degree, the maximum reactivation factor (ratio of survivals in UV-irradiated and non-irradiated hosts) being 1.50.