On the Nature of Reparable and Non-reparable Lethal Damage in E. Coli and Bacteriophage Induced by the Photodynamic Action of Acridine Orange

Summary

We studied the lethal photodynamic effect of AO on 10 strains of E. coli of the groups B and K12, differing in their ability to repair lesions caused by u.v. and ionizing radiation. The strains vary in their sensitivity to the photodynamic action of AO. These differences are at variance with the ability of the bacteria to repair their radiation damage.

The experiments on extracellular phages of E. coli revealed no multiplicity-, u.v.-, v- and x-gene reactivations after the photodynamic action of AO. In phage T3, repair by the host cell was observed in bacterial strains capable of repairing u.v.-irradiated phage (hcr⁺); this did not occur in phage T7.

In bacteria and DNA of phages T2, T4 and T7, AO-induced lesions differ in their nature from damage caused by u.v.-light. On the other hand, in DNA of phage T3, higher doses of visible light induced damage which could be partly repaired by bacterial enzymes of the excision repair system.