Growth of bacteriophage, titering, and transduction.

Bacteria must express the maltose receptor:

Under poor growth conditions, the lysogenic pathway is followed:

Under good growth conditions, the lytic pathway is favored:

Progeny phage are released from lysed bacteria:

PLAQUE GROWTH

Plaques enlarge by successive rounds of infection and lysis:

The extent of plaque formation depends on the Multiplicity of Infection (M.O.I.):

TRANSDUCTION

Conditions are chosen to promote lysogeny:

• Adsorb phage to DM700 at lower temperature (30? C)
• Grow bacteria on poor media (Minimal A glucose)
• Incubate plates at lower temperature (30? C)

Grow transductants under selective conditions, in our case we select for the ability to grow on media lacking cysteine

DATA TABULATION

Count the number of PFUs (or CFUs) on a series of plates:

Calculate the number of PFU (or CFU) per mL of phage stock

For example: 37 plaques were observed.

Hence, (37 plaques / 0.1 ml) x 10^6 dilution = 3.7 x 10^8 PFU / mL of original phage stock.