The Effect of Heat on the Ability of a Host Strain to Support the Growth of a Staphylococcus Phage

Abstract

A group of epidemiologically related strains of Staphylococcus aureus, which were untypable by standard methods, became sensitive to typing phage 187 after the inocula had been held at 56[degree] for 2 min. The strains were found to be lysogenic. Evidence is presented to show that the phage carried, phage 5504[image], was exerting interference against phage 187 which could be partially overcome by heat treatment Phage 187 grown in heated cocci was found to have undergone a host-induced modification which rendered it capable of lysing unheated lysogenic organisms. Active multiplication of the carried phage, phage 5504[image], appeared to be necessary for the multiplication of phage 187. Ultraviolet irradiation also increased the sensitivity of the strain to phage 187, but to a lesser degree than heat treatment. It is suggested that the effect of heating is to induce active multiplication of phage 5504[image] in the lysogenic culture, possibly by destroying a cyto-plasmic substance responsible for maintaining the carried phage in its prophage state.