An inducible antibacterial agent produced by a strain ofStreptococcus cremoris

Abstract

SummaryAn antibacterial agent is produced by ultraviolet (UV) irradiation ofStreptococcus cremorisstrain C11–56. Its production is accompanied by cell lysis and it attacks the strain C11–56 which produces it as well as a number of otherStr. cremorisstrains. A correlation between sensitivity to the antibacterial agent and sensitivity to trypsin has been demonstrated. Electron micrographs have shown the presence of particles resembling phage heads, most of which are empty, and of only very few intact phage-like particles in the lysate. The active agent in the lysate is associated with a particle ofM> 100000. The evidence suggests that the activity of the lysate may be due to the presence of a defective phage or of a lethal component of it.