Electrokinetic Studies on Bacterial Surfaces

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Abstract
The electrophoretic mobility of a group of widely different organisms was studied at pH 6.9 and ionic strength 0.02, as a function of the conc. of an anionic surface-active agent, Na tetradecyl sulfate, and a cationic agent, cetyl pyridinium chloride. The organisms included Micrococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Spirillum volutans, Bacillus pseudotetanicus, Mycobacterium smegmatis and M. phlei, Chondrococcus columnaris, and Spirochaeta sp. The effect of the anionic agent was usually to increase mobility only slightly at relatively high concs. An exception was a virulent strain of C. columnaris which showed a large increase in mobility at relatively low concs. After 18 months, during which the organism lost its infectivity for salmon, the anionic agent was without effect. The cationic agent showed, as a rule, a striking decrease in mobility with conc., frequently leading to reversal of charge. The slopes of the mobility conc., curves differed for the various organisms. In almost every instance, the mobility was stabilized at a conc., near 5 X 10-4 [image]. With M. aureus and E. coli, the concs. of the cationic agent which were lethal had, nevertheless, little effect on mobility.