INDUCED LYSOGENICITY AND MUTATION OF 

 BACTERIOPHAGE WITHIN LYSOGENIC BACTERIA 1 



by 



F. M. BURNET and DORA LUSH 



(From The Walter and Eliza Hall Institute, Melbourne). 



(Submitted for publication 29th November, 1935.) 



In the course of work on staphylococcal bacteriophages, we have encountered a 

 curious relation between two phages, one of which was apparently a mutant de- 

 rivative of the other. The only essential difference seemed to be that the original 

 phage produced resistant cultures with extraordinary facility while the presumed 

 mutant behaved in the normal fashion of any moderately active bacteriophage. 

 When we attempted to elucidate the nature of this difference, attention was first 

 concentrated on finding correlated differences between the two phages. No such 

 differences were found. The nature of the resistant cultures then became the 

 centre of interest. It was found that all the resistant forms appearing after the 

 action of the original phage were lysogenic, producing at first phage of the ' ' origi- 

 nal ' ' type. As the culture aged, the ' ' mutant ' ' phage made its appearance along 

 with the ' ' original ' ' 



Such relationships between phages, in the clear-cut form of this example, are 

 unique in our experience. Similar, if less striking phenomena, however, have been 

 recorded for other phages and bacteria, and the data obtained in the present work 

 may perhaps be of value to some of those interested in the interactions between 

 phage and susceptible bacterium. 



The phages in question, C and C, were described by Burnet and McKie in 

 1929, but the nature of their difference was not then investigated. Phage C was 

 obtained from rodent faeces and lysed only a white coccus SF, isolated from the 

 same source. The phage produced very little clearing in broth culture, though 

 filtrates gave fairly good plaque count titres. The plaques were highly character- 

 istic in appearance, very large for a coccal phage, about 3-4 mm. in diameter and 

 of annular form, the centre being invariably occupied by a heavy growth of bac- 

 teria, and the clear ring only a little more than a millimetre across. An unusual 

 but constant feature of the plaques is that they extend their diameter when the 

 plate is incubated for periods beyond 24 hours. To some extent the central bac- 

 terial growth also expands, but this lags relatively to the lysis, and the sum effect 



i This work was carried out under a grant for work on virus diseases, from the Commonwealth 

 Government Department of Health, and the Rockefeller Foundation. 



[Reprinted from The Australian Journal of Experimental Biology and Medical Science 

 14 : 27-38, 1936] 



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