Reactivation of Chlorine-Inactivated Escherichia coli

AVarious investigators have shown that irradiated bacterial cells can be reactivated by different nutrients.However, a controversy exists as to whether chlorinekilled bacteria can be made to recover by posttreatment.Heinmets et al. (1954) reported that they were able to restore the viability of chlorine-inactivated Escherichia coli strain B/r by incubating cells suspended in buffer supplemented with certain tricarboxylic acid cycle intermediates.The bacterial suspensions were incubated at 37 C for 24 hr and then plated out on minimal agar.No living bacteria were detected in buffer suspensions or in nutrient broth, whereas viable cells (up to 106) were found in buffer supplemented with tricarboxylic acid cycle intermediates.However, when plating was performed immediately without inter- mediate incubation (for 24 hr) in liquid medium, no reactivation occurred even if the plating agar was re- inforced with the above-mentioned metabolites.The validity of these results was questioned by Garvie (1955), who showed that E. coli strain 28D10 cotuld multiply in phosphate buffer and that the growth