TRANSDUCTION OF LYSOGENY IN ESCHERICHIA COLI 



213 



gous phage particles. With prophage X, no defective immune clone was 

 found. With phage 82, it was found that 2 out of 21 Gal+ clones which 

 did not produce infective phage were immune against phage 82 and its 

 virulent mutant, 82c. After ultraviolet induction, these two strains ex- 

 hibited a small degree of lysis, but no infective phage was released. After 

 several generations, both strains had become sensitive to phage 82. These 

 results suggest that recombination might have occurred between the 

 prophage and an homologous genetic fragment issued from nonlysogenic 

 bacteria. Unfortunately, because of the lack of markers on phage 82, no 

 genetic analysis was undertaken. 



Transfer of lysogeny. In order to demonstrate transfer of lysogeny, 

 nonlysogenic bacteria 678/X/82, 434 were infected with preparations of 

 363 grown on prototrophic bacteria lysogenic for one of the three phages 

 (82, X, or 434), and the bacteria were plated on various selective media. 

 The results of such experiments are listed in Table 4. As in the case of 

 nonlysogeny, lysogenic colonies were found only among those selected 

 for galactose utilization. For each prophage, the frequency of transfer 

 of lysogeny appears to be of the same order of magnitude as that found 

 for the transfer of non-lysogeny. 



TABLE 4 

 Transfer of Lysogeny 



Acceptor nonlysogenic P678/X/82, 434 bacteria were infected with one of three 

 preparations of phage 363 grown on prototrophic lysogenic strain, K12(82)+, 

 K12(X)''', and K12(434)+, respectively. After plating of each mixture on various 

 selective media, colonies were tested for their ability to release the correspond- 

 ing phage, 82, X, or 434. 



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