Expression of the lacZ gene in Escherichia coli irradiated with gamma rays

Exposure of bacterial cells to ionizing radiation damages cellular components and causes cell death. We examined the induction of the plasmid-encoded lacZ gene in Escherichia coli JM109 harboring pUC19 after irradiation with gamma rays. The data demonstrated that cells irradiated with 6 or 8 kGy gamma rays lost their ability to grow on nutrient agar plates, but retained the ability to induce lacZ gene expression by IPTG at about 10% the level of the nonirradiated control. Thus, inactivation of cells by irradiation may provide another option for establishing a vehicle of protein and DNA, as nonpropagating protein-producing apparatus, albeit with lower capacity than intact cells.