ACTION SPECTRA FOR PHOTOREACTIVATION OF MUTATION TO PROTOTROPHY IN STRAINS OF ESCHERICHIA COLI POSSESSING AND LACKING PHOTOREACTIVATING‐ENZYME ACTIVITY*

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Abstract
Abstract— The action spectrum and dose‐rate dependence for photoreactivation of mutation to prototrophy in late‐lag‐phase cultures of Escherichia coli H3r30 (which lacks active photo‐reactivating enzyme) are roughly similar to those for photoprotection from killing in other strains. It is suggested that photoreactivation of this mutation in H/r30 is an indirect effect, similar in mechanism to photoprotection. The action spectrum and dose‐rate dependence for photoreactivation of mutation to prototrophy in late‐lag‐phase cultures of E. coli H3r30‐R (which possesses active photoreactivating enzyme) are roughly similar to those for photoreactivation of killing in most other strains. It is suggested that photoreactivation of this mutation in H/r30‐R is a direct effect at long wavelengths, but that there is an indirect component at short wavelengths. A quite different interpretation of these data is noted. Finally, it is found that, under the conditions of these experiments, indirect photoreactivation of killing in H/r30 and H/r30‐R is weak or nonexistent.