Studies on the Antibacterial Action of Human Saliva

II. Observations on the Mode of Action of a Lactobacillus Bactericidin

¹ Department of Periodontics and Endodontics, Division of Research, University of Washington, School of Dentistry, Seattle

Some basic observations on the mode of action of a salivary lactobacillus bactericidin were made.

The lethal effect of this agent on actively multiplying L. acidophilus ATCC 4357 is apparently due to unbalanced growth. This was supported by the observations that killing of the organism was not accomplished by the saliva until an initial period of multiplication had occurred and that the antibacterial factor was without effect on resting organisms.

The minimal bactericidal concentration of the lactobacillus bactericidin was 1 unit per milliliter. One-half unit per milliliter showed temporary stasis, whereas one-quarter unit per milliliter showed no inhibitory effect.

The bactericidin apparently does not alter the morphology or Gram reaction of the organism. It is not adsorbed by the organism.