Metabolic process during the repair of freeze-injury in Escherichia coli

Abstract

After Escherichia coli was injured by freezing, the repair process was studied during incubation of the cells for 2 hr at 25 C in 0.5% K(2)HPO(4) at pH 7.0 in the presence of specific metabolic inhibitors. The repair in K(2)HPO(4) was not affected by inhibitors of the synthesis of protein, nucleic acids, and mucopeptide. These inhibitors prevented growth of the repaired cells in a minimal broth at 35 C for 24 hr (except actinomycin D and hydroxyurea). Several uncouplers of adenosine triphosphate (ATP) synthesis reduced the repair process in K(2)HPO(4), but only cyanide and azide prevented growth in minimal medium. Data indicated that the cells synthesized energy in the form of ATP and probably utilized it for the repair process. Addition of ATP also facilitated the repair of injury. The freeze-injured cells showed extreme susceptibility to surface-active agents and lysozyme. The repaired cells, like the uninjured cells, became relatively resistant to these compounds.