Observations on the saliva factor that enhances the production of lactic acid by the oral flora

Constituents of salivary supernatant responsible for stimulation of oxygen uptake by the bacteria in human salivary sediment

The 10,000 g supernatant of wax-stimulated whole saliva was fractionated by gel filtration and its components were tested along with amino acids, small peptides and urea for their ability to stimulate this oxygen uptake, and for their effects on pH. Fractions containing the larger components, the proteins and large peptides, stimulated much less oxygen uptake than unfractionated supernatant, and caused a small decrease in pH. Analysis with anthrone indicated that both these effects were due mainly to the carbohydrate associated with these constituents. In contrast, fractions containing the remaining lower molecular-weight components stimulated substantial oxygen uptake and a rise in pH; both effects were like those seen with whole saliva supernatant. The oxygen effects were attributed mainly to certain amino acids and small peptides in the small molecular-weight fractions. Ornithine, arginine, proline and glutamic acid consistently stimulated oxygen uptake by the oral microflora in a test of 23 amino acids with the sediments of 13 subjects. Ornithine and arginine at the same time stimulated a significant rise in pH, whereas the other two amino acids showed no such effect. Variable and sometimes significant oxygen uptake was seen with alanine, aspartic acid, asparagine, glutamine and cysteine in 4-7 of the subjects; infrequent or no effects were seen with the remainder of the amino acids tested. There was some evidence to suggest that amino acid stimulation of oxygen uptake may be inducible. Urea had no effect on uptake but did contribute significantly to the pH rise. Small peptides containing those amino acids that could stimulate oxygen uptake also stimulated such uptake; peptides without such acids did not.(ABSTRACT TRUNCATED AT 250 WORDS)

Metabolic differences between saliva from caries-active and caries- and restoration-free children

Sucrose consumption and lactic-acid production by saliva, and the effects of pH, were first evaluated by radio-isotope techniques in populations of caries- and restoration-free (CF), and caries-active from sucrose than saliva from CA subjects. Sucrose consumption also was significantly greater in saliva of CF subjects. These results occurred at pH 7.2 but not at pH 6.0 and 5.0. Lactic acid, total volatile products and carbon-dioxide (CO2) production by saliva were then evaluated in different CF and CA populations of children. Metabolic parameters in the presence and absence of salivary supernatant (SS) also were determined. Saliva of these CF subjects also formed significantly more lactic acid from sucrose than did CA subjects. The presence of SS increased lactic-acid formation in this saliva; the increase was significant in CF subjects. Total volatile products and CO2 were greater in saliva of CF subjects but were not affected by SS. Partial microbial characterization of each salivary specimen was conducted in both series of experiments. CF subjects harboured less Streptococcus mutans (parts I and II), total lactobacilli (parts I and II) and Actinomyces species (part II) than CA subjects. Differences for lactobacilli in the first population and Actinomyces species in the second were significant.

The identification of a peptide in human parotid saliva particularly active in enhancing the glycolytic activity of the salivary micro-organisms

A factor in saliva responsible for markedly activating the glycolytic activity of micro-organisms was isolated from parotid secretions and identified as a small basic peptide. Analysis of the peptide showed a high proportion of histidine, lysine and arginine. Its minimum molecular weight was calculated to be between 2500 and 3000.