Reduction of the adherence of Streptococcus sobrinus insoluble α- d-glucan by endo-(1→3)-α- d-glucanase

Insoluble α- d-glucan, previously formed on a glass surface from sucrose by the action of cell-free d-glucosyltransferases of Streptococcus sobrinus OMZ176, was significantly removed by a purified preparation of endo-(1→3)-α- d-glucanase (mutanase) from a strain of Pseudomonas sp. Almost complete dissociation of adherent glucan occurred at the highest enzyme concentration (40 mU/mL) tested. Synthesis and de novo adherence on glass of the glucan was markedly inhibited by the presence of mutanase, even at low concentrations (4 mU/mL or less). When compared to native glucan, the mutanase-modified glucan samples (a) contained lower proportion of d-(1→3) linkages; (b) showed lower susceptibility to mutanase and higher susceptibility to (1→6)-α- d-glucanase (dextranase); (c) contained larger amounts of low-molecular-weight fractions; (d) had lower intrinsic viscosities; (e) showed higher S. sobrinus cell-agglutinating activities; and (f) consisted of looser entwinement of coalescent single-stranded fibrils (a major component) and shorter double-stranded fibrils (a minor one).