TRANSDUCTION OF LYSOGENY IN ESCHERICHIA COLI 



215 



TABLE 5 



Development of Transduced X Prophage 



Preparation of 363 

 grown on K12(X)'^ 



Number of particles per 



milliliter forming a 363 plaque 



when plated on K12/X 



Number of particles per milliliter 

 forming a \ plaque when plated on 



K12(363)-* 



K 12/363 



Untreated 1.8 X lO^ 



10 minutes after addition 1.7 X 10* 



of anti-X serum 

 30 minutes after addition 1.9 X 10* 



of anti-X serum 

 Same preparation, previ- 3.7 X 10" 



ously treated with anti-X 



serum, 30 minutes after 



addition of anti-363 



serum 



2.3 X 10^ 1.15 X 103 

 1.2 X lO^" 1.3 X 102 



1.4 X 103 79 X 10' 

 4.1 X 101 4.9 X 10' 



To a preparation of phage 363 grown on K12(X)"'', anti-X serum was added at 

 time and the mixture was incubated at 37°. After 30 minutes, anti-363 serum 

 was added. Before addition of any serum, and at various times during the ex- 

 periment, samples were removed and diluted. Aliquots were plated as follows 

 (after 30 minutes preadsorption at 37°) : ()) on K12/X (for plaques of 363) j {2) on 

 K12(363)+, which adsorbs both X and 363 without multiplication of the latter 

 (for total X plaques); (3) on K12/363, which adsorbs X but not 363 (for free X 

 phage). Figures indicate the number of plaques found without treatment, after 

 treatment with anti-X serum alone, or after successive treatments with both 



efficiency of plating on K12, K12(363)+, or K12/363. In the prepara- 

 tions of 363 grown on lysogenic K12(X)+, there are always some free X 

 particles which have been released during the growth of the bacteria. 

 Such preparations give the same number of X plaques on K12, K12(363)"'", 

 and K12/363. When most of the free X particles are neutralized by anti-X 

 serum, a higher number of X plaques is found by plating on K12(363)+, 

 which adsorbs 363 without allowing its multiplication, than on K 12/363 

 phage, which does not adsorb phage 363. If, now, the preparation pre- 

 viously treated with anti-X serum is exposed to anti-363 serum, the 

 number of X plaques on K12(363)''' is reduced at a rate similar to the one 

 found for inactivation of total plaques of 363. After about 30 minutes 

 of exposure to anti-363 serum, the same number of X plaques is found by 

 plating on K 12 (363)+ or on K 12/363. 



The results of this experiment show, therefore, that at 37° the X ma- 

 terial carried in particles of phage 363 is able to multiply vegetatively 



347 



