The production of polysaccharides from sucrose by extracellular enzymes from oral Streptococcus salivarius isolates and the physico-chemical properties of water-insoluble products (IPs) were investigated . Extracellular enzymes from all the 18 strains tested produced insoluble a-D-glucans (IGs) as well as soluble /3-Dfructans, and formed adhering deposits on glass . Generally, the IPs (mostly IGs) of S. salivarius strains differed from the S. sobrinus IPs by (a) containing significant proportions of a-D-(1--*4)-, in addition to a-D-(1--->3)-and a-D-(1--*6)-glucosyl linkages, and much higher proportions of a-D-(1--.3) than a-D-(1--*6) linkages, (h) being more susceptible to hydrolysis by mutanase than by dextranase, (c) possessing low or no streptococcal cell-agglutinating ability, and (d) showing weaker adhesion to a glass surface . The degree of the polysaccharide adherence differed greatly among the S. salivarius strains and, therefore, they were divided into three groups of adherence producers ; heavy, moderate, and slight . The IPs of the three groups contained, generally in descending order, a higher proportion of higher-molecularweight fractions, and consisted of higher proportions of IG containing higher proportions of -(1-a6)-a-D and -(1-)-4)-a-D glucosyl linkages and (1-->3,6) branches, but showed higher susceptibility to hydrolysis by mutanase as well as dextranase. Thus, the production and the properties of extracellular insoluble a-Dglucans from sucrose differ considerably between oral S . salivarius and cariogenic
S. sobrinus .
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