Differential Photoreactivation of Escherichia coli after Exposure to 2650 and 2250 A Ultraviolet.

Abstract

Photoreactivation of both inactivation and mutation occurs after exposure of E. coli SD-4 to 2250 and 2180 A UV. The magnitude of photoreactivation (PR) after exposure to short-wavelength UV in E. coli B/r and its derivatives is conpounded with a shortwave-length UV sensitization to inactivation by the PR light itself. The quite different response to PR light exhibited by E, coli strain 42-24, presumably not derived from E. coli B/r. suggests that different strains may differ in response to UV and PR light. A number of unrelated strains should be studied before generalizations are made about mechanisms of radiation action in bacteria.