Electrophoretic potential and virulence of diphtheria bacilli.

Abstract

Measurements of electrophoretic velocities on strains of pneu-mococci and other organisms indicate that many vital phenomena are closely associated with the electrokinetic P. D. between the organism and its menstruum.

It has become evident from the work of Falk and his associates 1 that there are significant parallelisms, direct or inverse, between electrophoretic potential, virulence, agglutinability and other characteristics of bacteria. For pneumococci of the types 1, 2, 3, 4 it has been found that the P. D. is higher the greater the virulence for white mice and vice versa.

The work here reported was undertaken to determine whether or not P. D. would parallel virulence of various strains of diphtheria bacilli as well as to obtain comparable data in regard to P. D. on avirulent or pseudodiphtheria bacilli.

The cataphoretic potentials on corynebacteria were determined by the method described and used by Falk, Gussin and Jacobson. 1 For reasons discussed by them results are expressed in terms of observed velocities (μ/sec) instead of expressing the electrical P. D. at the interface between the bacterium and the menstruum in millivolts.

P. D. in observed velocities (μ/sec) may be converted into millivolts by multiplying by the factor 1.3. Ten measurements of velocity (5 with one and 5 with reversed orientation of the electrical field) were made at stationary layers V_s133, 497, in the same medium in which the bacteria were grown. The same methods were used in measuring velocities of cells in distilled water.

The electrokinetic P. D. on 65 strains of corynebacteria parallel the virulence (toxigenicity) of these bacteria. Measurements of potential on 48 hr. veal broth cultures of toxigenic strains give potential differences of 4.2 to 1.0 (μ/sec) with an average of 3.4 (μ/sec).