The oxygen effect in E. coli WP2: the role of the photoreactivatable component in modification of the oxygen effect in E. coli WP2 uvrA6.

The role of photo-products induced by secondary U.V. which accompanies high-energy gamma-radiations has been studied in bacteria in the presence and absence of oxygen. The photodamage makes an essential contribution to the lethal effect of ionizing radiation in U.V.-sensitive strains in anoxia and thus can influence the value of the oxygen effect. When the secondary U.V.-contribution was minimized (irradiation by X-rays or gamma-rays in the presence of 1 per cent nigrosine) the oxygen enhancement ratio was shown to increase and approximate to that for E. coli WP2 cells.