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Fd-tet has a replication defect and this makes it impractacle impractical to titer by pfu. Rather, the titer can be measured in terms of transducing units (TU). Simply, cells infected with fd-tet will gain tet resistance and therefore will form colonies on tetracycline plates. The number of colonies formed gives the number of TU. This number is typically 20x lower than the number of phage particles (which can be measured with nanodrop if high enough concentration).
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7. Add 1 mL of NZY with .2ug/mL tet. Then shake the tube (upside down at 250 rpm) at 37 degrees for 30 minutes. This will allow infected cells to express the tet-resistance genesgene.
8. Serial dilute the cells (from step 7) up to 1E-3 in NZY with 15 ug/mL tet. Spread 100 uL of each dilution (up to 1E-3) onto a pre-warmed NZY plate with 40 ug/mL NZY. Invert the plate and put it in the 37 degree incubator overnight. Count the colonies the next day.
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