The Effect of N-Ethylmaleimide on the Radiation Sensitivity of Bacteria

Abstract

Sensitization of Escherichia coli strain B/r to gamma-radiation takes place within a few minutes of the addition of N-ethylmaleimide. Sensitization was demonstrated with as little as 0.0001 M-N-ethylmaleimide, but a much higher concentration (> 0.002 M) was necessary for any bactericidal effect. The N-ethylmaleimide had to be present during irradiation in order to be effective. Staphylococcus aureus and a Pseudomonas sp. but not spores of Bacillus subtilis, were also sensitized by N-ethylmaleimide. The Pseudomonas sp. was only sensitized under anoxic conditions; this may indicate that, with this organism, N-ethylmaleimide and oxygen acted competitively to enhance radiation damage. Possible mechanisms of sensitization are discussed.