STUDIES ON HOST-SPECIFICITY OF BACILLUS SUBTILIS-PHAGE (S-a), WITH SPECIAL REFERENCE TO ITS BEHAVIOUR TOWARD PROTOPLASTS

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(1) A strain of bacteriophage (phage S-a) attacking an amylase-forming bacterium, Bacillus subtilis var. amyloliquefacus (a.f.), was investigated with special reference to the host specificity of the phage, as well as its multiplication on protoplast hosts.
(2) The protoplasts of the susceptible bacterial strain, Bacillus subtilis var. amyloliquefacus (a.f.), were found to be capable of adsorbing the added phage and producing infectious daughter phages. The rate of phage-adsorption and the burst number in the one-step growth-experiment were determined, and the results compared with those obtained with intact bacterial cells as hosts.
(3) Protoplasts of non-susceptible bacteria, Bacillus subtilis NRRL 558 (non-a.f.), were also found to be capable of adsorption the phage but to a less pronounced extent and with no subsequent reproduction of the phage.
(4) Protoplasmic membranes of susceptible and non-susceptible bacteria were equally found to adsorb phage particles, but in a non-specific way.
(5) A correlation was discovered between lysozyme-susceptibility of bacterial cells and their capacity for phage-adsorption. The latter property was found to meet a necessary requirement, but not the sufficient condition for phage-susceptibility; Bacillus subtilis NRRL 558 (non-a.f.; lysozyme- susceptible; phage-adsorbing), for example, was found to be non-susceptible to phage S-a.