AN INDUCIBLE ANTIBACTERIAL AGENT PRODUCED BY A STRAIN OF STREPTOCOCCUS CREMORIS

An antibacterial agent is produced by ultraviolet (UV) irradiation of Streptococcus cremoris strain 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 other Str. cremoris strains. 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 of M > 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. © 1969, Proprietors of Journal of Dairy Research. All rights reserved.