Abstract
1) Most of bacteriophage P7 particles liberated from host bacterium (Sh. dysenteriae type II) by massive lysis, combine with bacterial debris and are inactivated. This inactivation proceeds gradually during preservation at low temperature.
2) This attachment is reversible and combined phage dissociates by heating, but in order to acquire maximum dissociation, it is necessary to dilute the phage-stock before heating. Some examples of the relationship between time and temperature to acquire maximum dissociation are as follows: 2 minutes above 50°C, 20 minutes in 43°C and 2 hours in 37°C.
3) Being unable to use as material of experiment the phage-stock containing phage that is reversibly inactivated, we removed the debris from lysate by centrifugation at 10, 000 R. P. M. for 20 minutes after heating 10 minutes at 63°C.
4) We discussed the above phenomenon comparing with other phage-systems of stable titer, and inferred that the attachment of phage to the bacterial debris might probably be caused by phage-receptor, left on the bacterial debris.
5) Pleomorphism of plaque size is related to this reversible inactivation of the phage.
