Environmental Conditions Affecting the Expression of X-Ray-Induced Lethality in an Auxotrophic Bacterium

Abstract

The influence of postirradiation nutritional deprivation on cell survival was studied in a multi-auxotrophic bacterium Escherichia coli strain T"A"U. The postirradiation effect is probably not due to toxic substances induced in the medium as a result of irradiation. The possibility that the portion of the cells subjected to immediate lethal damage may release infectious or toxic agents was explored by using nonirradiated cells suspended in the cell-free supernatant after postirradiation incubation. Cell death did not occur. Irradiated cells incubated in liquid medium were greatly modified if the cells were post-treated on a filter paper carrier under conditions of nutritional deficiency. Nutritional deficiency leading to cessation of deoxyribo-nucleic-acid (DNA) or ribonucleic-acid (RNA) and protein synthesis may result in the expression of lethal injury.