Leon Buchbinder

A Preliminary Report on the Relation of Dental Aciduric Bacteria To Lactobacillus Acidophilus

Twenty-one strains of aciduric bacteria isolated from teeth, and nine strains of known Lactobacillus acidophilus, have been studied comparatively in their morphological, biochemical, and serological relations. The dental strains were isolated from the mouths of an unselected group of clinic patients of the School of Dental and Oral Surgery of Columbia University. Inoculations were made into 1 percent glucose meat infusion broth, pH 5.0, and the cultures incubated 48-72 hours at 370C. All cultures showing Gram-positive rods were streaked on casein digest agar and incubated 48 hours. Typical, faint, punctiform colonies were then transferred back into pH 5.0 broth. Three or four platings were necessary in some cases to obtain pure cultures. Nine strains of known L. acidophilus of the intestinal type were obtained from several sources as pure cultures. These, and the 21 pure cultures of dental aciduric organisms, were kept growing uniformly in casein digest broth throughout the course of the work. No consistent difference could be discovered between the groups in any part of this study. On the whole there was indication of a slightly greater homogeneity in the intestinal group than in the dental group. This was, perhaps, to be expected from the conditions under which the two groups were obtained. The appearance of the growth in broth was found to depend more on the age and extent of the growth than on any intrinsic difference in growth tendency between the groups. All of the strains showed uniform turbidity in the broth at the first appearance of growth; most of the strains of both groups