The effect of storage and lag time on MS2 bacteriophage susceptibility to ultraviolet radiation.

The susceptibility of MS2 bacteriophage suspensions to UV radiation was assessed using a collimated beam technique. Storage of MS2 bacteriophage cultures at 4 degrees C resulted in a decrease in phage susceptibility to UV radiation over time. After 18 days, the level of MS2 bacteriophage inactivation achieved for the range of UV doses tested decreased by 0.7 to 1.1 logs, but remained constant after that point. Changes in the protein coat of the bacteriophage, a decrease in viability over time, and an increase in coagulation may have played a role in the observed susceptibility decrease. A 2-hour lag time between the preparation of the MS2 suspension and the irradiation test also resulted in a decrease in phage susceptibility.