A Study of the Changes Occurring in Radiosensitivity during Spore Germination

The changes in sensitivity to ultraviolet irradiation occurring during the germination of spores of Bacillus megaterium are reported. A comparison of nonlysogenic, noninducible lysogenic, and inducible lysogenic stains reveals that until elongation of the germinating spore begins there is very little difference among the three types. At that point the multiplicity of the survival curves or the first two types increases from two per cell to about four to eight per cell in the vegetative cell. The over-all increase in sensitivity is about a factor of 3. For the case or inducible lysogenic strains, however, the survival curve changes from a multiplicity or two per cell at the beginning of elongation to one pre cell, where it remains. The sensitivity also increases greatly from this point on, until that of the vegetative cell is about forty times that of the germinating spore before elongation.