Characteristics of bacteriophage N1 and its attachment to cells of Micrococcus lysodeikticus.

Bacteriophage N1 was purified by differential and equilibrium gradient centrifugation and characterized with respect to bouyant density in CsCl, one-step growth properties, host range, and morphology by electron microscopy. In a tris (hydroxymethyl) aminomethane-magnesium buffer (pH 7.15), the irreversible adsorption of N1 to cells of Micrococcus lysodeikticus strain 1 (ML-1) followed first-order reaction kinetics with an adsorption-velocity constant of 1.6 x 10(-9)/min at 32 C. The rate of phage attachment was not significantly altered when adsorption mixtures contained 0.01 m KCN or 1% casein hydrolysate, 0.01 m CaCl(2), and 0.001 m tryptophan. The activation energy for the irreversible adsorption reaction was 8.6 kcal. Treatment of ML-1 cells by any of the following procedures reduced the irreversible phage receptor activity over 90%: (i) mechanical disruption, (ii) lysozyme digestion, (iii) incubation in 1% cetyltrimethylammonium bromide, or (iv) incubation of heated cells (100 C, 15 min) with trypsin, Pronase, or lysozyme. The sensitivity of the phage receptor activity of ML-1 cells to lysozyme suggests that the bacterial cell wall is involved in the receptor site for the virus. Destruction of receptor activity by the other treatments cited above implies that, in addition to the cell wall, other cellular components may participate in the irreversible attachment of N1 phage to cells.