Combined extracellular sucrolytic enzyme power from a strain of Streptococcus mutans, and purification results

Abstract

abstract— Streptococcus mutans has been shown to produce extracellular invertase, dextransucrase, and levansucrase. The purpose of this work was to study the relative quantities of these enzymes in pure culture supernatant, and in samples from commonly used purification methods. The strain “Ingbritt” was selected because it is a well‐defined human strain, available, and with well‐known growth requirements. The samples were incubated with sucrose for the determination of free monohexoses, and the polysaccharide from ethanol precipitation was hydrolyzed as previously described. In cell supernatant the inversion effect exerted 75% of total sucrolytic power, the dextransucrase 20% and the levansucrase 596. No method, tested in this work, could separate all the activities completely.

Oral Starch Degradation and Its Influence on Acid Production in Human Dental Plaque

“…Factors contributing both to the rate of starch hydrolysis and to its oral clearance seem to be of equal importance in determin ing the acidogenic potential of a starch-con taining product.Thus, the results of intraoral plaque pH telemetry with starch-containing foods showed a greater variability than those obtained with sucrose [Imfeld, 1978], a substrate which can be metabolized direct ly by plaque bacteria and can diffuse into plaque [Asknes, 1976[Asknes, , 1978. The results of previous experiments on the influence of starch on glycolytic acid formation in saliva and plaque in vitro [Miller, 1890;Morch, 1961;Frostell, 1970Frostell, , 1971Birkhed and Fuchs, 1975;Birkhed and Skude, 1978] and in vivo [Stephan, 1940;Neff, 1967;Graf, 1969;Imfeld, 1977] were confirmed for the wheat starch preparations used in this work.…”