DIPHTHERIA-PHAGE INHIBITOR PRODUCED BY TREATING THE HOST BACTERIUM WITH OLEIC ACID

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Abstract
An inhibitor of diphtheria phage B is produced when its host strain C4 of Corynebacterium diphtheriae is exposed to oleic acid while suspended in a proteose peptone broth medium. The inhibitor can be demonstrated in the supernatant after removal of the cells by centrifugation. When 108 cell/ml were exposed to 10 [mu]g/ml of oleic acid for 10 min at 37 C, enough inhibitor was produced to inactivate 60 to 90% of added phage within 10 min. Inhibition is dependent on the presence of some material derived from the host cell and on oleic acid. In addition to this activating role, oleic acid also enhances the release of cellular material participating in inhibition. The influence of a number of variables on inhibitor production was examined. Cells in the logarithmic phase of growth and the phase of decline were equal in their ability to participate in inhibitor production. The rate of inhibition was related directly to the cell and oleic acid concentrations employed in producing inhibitor and in general inversely related to the times the cells were exposed to fatty acid. Cells heated to 60[degree] C for 15 min lost ability to participate in inhibitor production. In a preliminary study of the specificity of inhibition it was found that diphtheria phage B and related phages were inhibited by material derived from C. diphtheriae strain C4 but that coliphages T1, T2, T3 and T5 and phage C of Bacillus megaterium were not. In addition, no inhibition of diphtheria phage B was observed when super-natants were tested following treatment of a strain of Escherichia coli and a Bacillus species with oleic acid in a manner analogous to that employed in inhibitor production.