Repair of Thermally Induced DNA Breakage in <Emphasis Type="Italic">Escherichia coli</Emphasis>

BACTERIA grown at above optimal temperatures progressively lose viability^1,2. The degree of sensitivity is a genetic trait, correlated with sensitivity to ionizing radiation in E. coli and is characterized by single-strand DNA breaks³. The loss of viability is partly reversible by keeping the cells in buffer at a lower temperature⁴. Rosenberg et al.⁵ found a numerical correlation between the thermodynamic parameters of protein denaturation and observed death rates of various organisms and suggested that protein denaturation was a likely cause of cell death. We show here that strand breakage and the repair of this breakage parallel the observed changes in viability during thermal inactivation in E. coli.s