Dynamics of the pseudolysogenic response in slowly growing cells of Pseudomonas aeruginosa.

Abstract

Pseudolysogeny is an environmental condition in which the starved bacterial cell coexists in an unstable relationship with infecting viral genomes. As nutrients are supplied to the bacterium, the pseudolysogens resolve into either true lysogeny or active production of virions. The direct result of pseudolysogenic relationships is an extension of the effective phage half-lives in natural environments. In this paper a continuous culture model of interactions between bacterial host organisms and bacteriophages leading to pseudolysogeny is presented. The pseudolysogenic state was found to depend on the concentration of nutrients available to the host. As cells became more starved, the frequency of pseudolysogens increased. The dependence on overall nutrient concentration was more dramatic than the variation in the generation time (chemostat turnover time) of the host. Thus, it appears that pseudolysogeny is a legitimate strategy for environmental bacteriophages to adapt to survive periods of starvation of their host organisms. Consideration of pseudolysogeny as a survival strategy is important to the development of any comprehensive model of host-bacteriophage relationships in natural environments.