DYNAMICS OF THE PSEUDOLYSOGENIC RESPONSE IN SLOWLY GROWING CELLS OF PSEUDOMONAS-AERUGINOSA

Pseudolysogeny is an environmental condition in which the starved bact erial cell coexists in an unstable relationship with infecting viral g enomes. As nutrients are supplied to the bacterium, the pseudolysogens resolve into either true lysogeny or active production of virions. Th e direct result of pseudolysogenic relationships is an extension of th e effective phage half-lives in natural environments. In this paper a continuous culture model of interactions between bacterial host organi sms and bacteriophages leading to pseudolysogeny is presented. The pse udolysogenic state was found to depend on the concentration of nutrien ts available to the host. As cells became more starved, the frequency of pseudolysogens increased. The dependence on overall nutrient concen tration was more dramatic than the variation in the generation time (c hemostat turnover time) of the host. Thus, it appears that pseudolysog eny is a legitimate strategy for environmental bacteriophages to adapt to survive periods of starvation of their host organisms. Considerati on of pseudolysogeny as a survival strategy is important to the develo pment of any comprehensive model of host-bacteriophage relationships i n natural environments.