The choice of bacterial strain is important. Choose a host in which lambda replicates vigorously, e.g. use strain Y1090 for a lambda gt11 clone. Stab a well-separated plaque with a sterile toothpick and rinse the captured lambda phage particles into the cells aliquoted above. Allow the phage to adsorb to the cells for 15 minutes at room temperature. Add 2 ml Tryptone Broth containing 10 mM MgSO4 and shake the culture at 37 o C until the culture is lysed.
Lysis is evident when the culture becomes clear and cellular debris is prevalent.
This will take anywhere from 4 to 8 hours depending on both the host and lambda strain used. Add 10-100 l chloroform and continue shaking to complete lysis if necessary. Pellet cellular debris at 10,000 rpm for 5 min. Pour the supernatant into a new 2 ml tube. Let the sample sit at 4 o C for 1 hr to overnight.