The Effects of Nitrogen Mustard on Escherichia coli

Abstract

Nitrogen mustard (HN-2)-resistant strains of E. coli have been obtained by repeated exposure of ca. 2.109 cells to concns. of the chemical permitting survival of only a few colonies. The selected HN-2 resistant strains may be treated for 1 hr. at 37[degree]C in [image]/5 Na2HPO4 buffered solns. of 0.1% HN-2. Surviving cells include phage resistant mutants (B/1 and B/1,5). Other survivors, defined as delayed mutants, yield phage resistant cells only after one or more divisions of the sensitive progenitors. Treatment of HN-2 resistant strains with u.-v. light reveals that the majority are viable at levels of irradiation lethal to normal cells. Independent strains of E. coli resistant to u.-v. light but never previously treated with HN-2, survive relatively high concns. of the chemical. These findings support the conclusion that the mode of action of nitrogen mustard and u. -v. radiation may be similar.