thesis

THE INTERACTION BETWEEN LAMBDA PHAGE AND ITS BACTERIAL HOST

Abstract

Our interest in the adsorption of lambda phages onto bacterial cells was triggered by the controversial results Schwartz obtained in the 70's (Schwartz 1976). Lambda phages bind to specific receptors, named LamB, on the cell's surface during the infection process. Phage adsorption onto the cell wall is a diffusion-limited process. One of the controversies is the rate of adsorption, which in some cases appears to exceed the theoretical limit imposed by the physical law of random diffusion. We revisited this problem by carrying out experiments along with new theoretical analyses. Our measurements show that the population of unbound phages decreases with time in a double-exponential fashion. Using fluorescence microscopy we quantified the number of receptors per cell. This dissertation describes the adsorption of lambda phages onto their host cells and a kinetics model, which allows the calculation of adsorption, desorption, and irreversible binding rates from a single measurement. The long-term interaction between lambda phage and its bacterial host in a co-habitual environment is approached as well. A complex mathematical model describing the dynamics of the two populations (bacteria and phages) is presented along with experimental results. Surprising phenomena of bacterial persistence against phage infection are also reported

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