140 APPENDIX A 



this culture into 1.3 liters of nutrient broth. 

 Aerate at 37°C for 4 hours or until culture con- 

 tains from 5 X 108 to 1 X iqs cells per ml. 

 Use this young culture. 



Phage suspension. Grow 20 ml of culture of 

 E. coli B with aeration at 37°C to a density of 

 about 2 X 10* cells/ml. Infect with a drop of 

 phage suspension containing 10^ to 10* infective 

 units. Continue incubation until visible lysis 



occurs. Determine infective titer. Dilute as 

 called for. 



Soft agar. 



bacto-tryptone, 10 gm, 

 Difco agar, 7 gm, 

 sodium chloride, 5 gm, 

 water to 1 liter. 



Nutrient agar plates. 2.3% nutrient agar in 

 distilled water. 



