Reversibility of the Adsorption of Bacteriophage PL-1 to the Cell Walls Isolated from Lactobacillus casei

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Abstract
Bacteriophage PL-1 adsorbed specifically to fragments of the isolated cell walls of its host L. casei ATCC 27092 and failed to adsorb to cell wall fragments of resistant strains. Soon after mixing, an equilibrium situation of phage adsorption was attained. The equilibrium position was dependent on the cell wall concentration, but was not affected by the incubation temperature. The adsorbed phages were not inactivated by the cell wall fragments, but formed phage-cell wall complexes maintaining original phage infectivity. The infectivity of phage-cell wall complexes was neutralized by antiphage sera in the same manner as free phages. When the phage-cell wall complexes were repeatedly washed by centrifuging and resuspension in a fresh medium, the adsorbed phages were eluted as infective virions, confirming that phage adsorption was reversible. When the reactants concerned were allowed to approach equilibrium from the opposite direction, the same equilibrium state was achieved. The value of the equilibrium constant with respect to reversible adsorption was constant with various phage concentrations under the conditions used here. When a mixture of phages and cell walls at an equlibrium state was diluted, the unadsorbed phages increased in accordance with the decrease in the concentration of the reactants.