THE INTRACELLULAR GROWTH OF BACTERIOPHAGES 



I. Liberation of Intracellular Bacteriophage T4 by Premature Lysis 

 WITH Another Phage or with Cyanide 



By a. H. DOERMANN*. t 



{From the Department of Genetics, Carnegie Institution of Washington, 

 Cold Spring Harbor) 



(Received for publication, August 20, 1951) 



Direct studies of bacteriophage reproduction have been handicapped by the 

 fact that the cell wall of the infected bacterium presents a closed door to the 

 investigator in the period between infection and lysis. As a result it was im- 

 possible to demonstrate the presence of intracellular phage particles during this 

 so called latent period, and, much less, to estimate their number or to describe 

 them genetically. This barrier has now been penetrated. It is the purpose of the 

 first two papers of this series to describe two methods for disrupting infected 

 bacteria in such a way that the intracellular phage particles can be counted and 

 their genetic constitution analyzed. 



The first method used to liberate intracellular bacteriophage depends on the 

 induction of premature lysis in infected bacteria by "lysis from without" 

 which occurs when a large excess of phage particles is adsorbed on bacteria (1). 

 It was found by nephelometric tests that T6 lysates are efficient in disrupting 

 cells when moderately high multiplicities are used (2). The further observation 

 was made that the addition of a large number of T6 particles to bacteria previ- 

 ously infected with T4, would, under some conditions, cause liberation of T4 

 particles before the expiration of the normal latent period of these cells. It 

 therefore seemed hopeful that a method of reproducibly disrupting infected 

 bacteria could be developed on the basis of this preliminary knowledge. 



* The experiments described here were carried out while the author was a fellow 

 of the Carnegie Institution of Washington. The author is indebted to Dr. M. Demerec 

 and the staff of the Department of Genetics of the Carnegie Institution of Washington 

 for providing facilities for this work. In particular the stimulating discussions with 

 Dr. Barbara McClintock are gratefully acknowledged. The manuscript was prepared 

 while the author held a fellowship in the Department of Biology of the California 

 Institute of Technology. He is grateful to Dr. G. W. Beadle and the staff of that de- 

 partment for their interest in this work, and especially to Dr. Max Delbriick for 

 criticism of the manuscript. 



X Present address: Biology Division, Oak Ridge National Laboratory, Oak Ridge, 

 Tennessee. 



Reprinted by permission of the author and The Rockefeller 



Institute from The Journal of General Physiology, 35 (4), 



645-656, March 20, 1952. 



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