Studies on Encapsulated Lactobacilli. III. Human Oral Strains

¹ School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania

The occurrence of mucoid (encapsulated), smooth, and rough lactobacilli in 226 samples of human saliva was investigated. Using serologic (specific capsular reaction, fluorescent antibody labeling) and cultural methods, mucoid organisms were found in about 11 percent of the population with a mean value of 6x10³ organisms/ml. saliva (range 1x10³ to 7x10³ organisms/ml. saliva). Smooth lactobacilli occurred in 35 percent of samples but in the smallest numbers (1x10³ organisms/ml. saliva).

The mucoid lactobacilli were found to be homogenous consisting primarily of homofermentative strains the majority of which closely resembled L. casei var. rhamnosus. Gel diffusion and chemical studies of several of the isolated capsular polysaccharides indicated that only one major kind of capsular material is produced, although considerable variation exists in the amount produced by individual organisms within a given pure culture. The major components of the capsular polysaccharides were rhamnose, glucose, and galactose.