STUDIES ON THE HOST-VIRUS RELATIONSHIP IN A LYSOGENIC STRAIN OF BACILLUS MEGATERIUM I

Abstract

The source and method of release of the free bacteriophage found in a lysogenic strain of B. megatherium was studied utilizing single-cell and spore isolations. Initial expts. with mass cultures demonstrated that the growth of the bacteria was paralleled by an increase in free bacteriophage throughout the logarithmic growth phase of the organism, and that the bacterio-phage/bacteria ratio was about 10/1. The growth and division of more than 550 cells was followed microscopically and in no case was free bacteriophage detected except after a cell had been observed to lyse. The conclusion arrived at is that the free bacteriophage found in this lysogenic culture is released by lysis of certain cells of the culture, designated susceptibles, and that such cells arise at a regular rate from normally resistant parent cells. This reversion rate to sensitivity is calculated to be about 2%.