Studies on Colicin B

The formation and the bactericidal action of colicin B, which had not been studied, were examined. When colicin B-producing cells were incubated with a low concentration of EDTA in water at 37°C for 30 min, almost all of colicins were extracted from cells into the surrounding medium. This technique was extremely effective for colicin I, which was not excreted into medium under usual conditions.Colicin B inhibited many macromolecular functions in the sensitive E. coli cells simultaneously, i.e., O2 uptake, oxidative phosphorylation, permeation activity for o-nitro-phenyl β-galactoside (ONPG) through cell membrane, and syntheses of protein, RNA and DNA.Colicin B could not be distinguished from colicin K by the cross-immunity test using K-colicinogenic strains. Colicin B had also many resemblances in the mode of action to colicine K, although their action was observed to be different in some points. These results indicated close relationship between colicins B and K.