title: Extracellular polysaccharides of smooth and rough variants of Streptococcus salivarius.
abstract: Some, but not all strains of Streptococcus salivarius were demonstrated to occur in smooth (S) and rough (R) variants, growing in distinctly different colonies on sucrose-containing agar plates. Sucrose-derived extracellular polysaccharides (EP) of NCTC 8606, ATCC 9759 S and R, ATCC 13419 S and R, 1A S and R, and Tove S and R were isolated, purified, and chemically studied. Extracellular enzymes of R variants yielded more water-insoluble than soluble material, while the opposite was true for S variants. The insoluble material consisted mainly of glucan, the soluble mainly of levan. Enzymatic hydrolysis suggested a predominance of alpha-1,3-linkages in the water-insoluble glucan. Cell-associated enzymes gave rise to cell-associated and -free EP. The cell-associated EP of S variants was insoluble, while that of R variants contained water-insoluble glucan and water-soluble fructan. Cells coated with cell-associated EP flocculated due to interaction of the EP, mainly by hydrogen bonding, in part by divalent cation bridging. The sucrose-derived EP gave rise to plaque deposit formation in sucrose broth cultures, S variant deposits being thin and firmly adherent to glass, R variant deposits being thick, rough, coherent, but only weakly adherent. The variant types were not altered by the curing agents ethidium bromide and acridine orange.
mesh_terms: D011135:Polysaccharides, Bacterial / Q000302:isolation & purification* / Q000378:metabolism; D013291:Streptococcus / Q000145:classification / Q000166:cytology* / Q000201:enzymology / Q000378:metabolism; D013395:Sucrose / Q000378:metabolism
chemical_list: D011135:Polysaccharides, Bacterial; D013395:Sucrose