During the course of studies to quantify host cell survival after infection with bacteriophages, we noticed low frequency of clones with novel phenotypes. Some of the survivors of infection with both UT1 and Phage S produced a brown pigment. The pigment can be seen after a couple of days of incubation at room temperature. The brown pigment-producing pseudolysogens were included in the test of the resistance of these cells to ultraviolet radiation. Both cell types, pigmented and unpigmented, exhibited at least a ten fold higher survival than the non-pseudolysogens at longer exposures.
Preliminary experiments suggest that a similar resistance is also present to solar radiation.
Phage S pseudolysogens were examined for resistance to hydrogen peroxide. The survivors of infection with the lytic bacteriophage UT1 appear to be unstable pseudolysogens. It is very difficult to grow clones to midlog phase without induction of lysis although the cultures may be grown at 30C with some success. Clones are unstable so that the same cell line may not show the same results the next time the experiment is done. A second general characteristic of the pseudolysogens is that they may not release phage consistently.