An evaluation of the rate constants for the adsorption of the defective phage PBS Z to Bacillus subtilis.

The adsorption of the defective phage PBS Z of Bacillus subtilis has previously been assumed to proceed in two steps, a reversible adsorption of extended phages followed by contraction of the adsorbed particles (Steensma, 1981a). This model, also used for other phages, explained the biphasic character of the adsorption curve, but a discrepancy was found between the calculated and observed concentrations of adsorbed, extended phages. Computer simulations indicated that this might be caused by inhomogeneity of the phage preparations with respect to their adsorption properties and that in that case other models would also fit the experimental data. Discrimination between the models was not possible on the basis of the available information on PBS Z and it was therefore concluded that the values reported previously for the rate constants (Steensma, 1981a) should be used with caution.