Title: Synthesis of intracellular iodophilic polysaccharide by Streptococcus mitis
Abstract: The synthesis of iodine-staining polysaccharide from glucose has been studied using a strain of Streptococcus mitis. Polysaccharide was shown to be intra-cellular, and to be a polymer composed solely of glucose linked in part by alpha 1, 4 glucosidic bonds. During exponential growth, the organism was found to synthesize polysaccharide at a rate proportional to the biosynthesis of bacterial nitrogen. When cultures entered the stationary growth phase, synthesis of microbial nitrogen decreased whereas polysaccharide synthesis continued for some time. This metabolic imbalance produced cells rich in intracellular polysaccharide. Comparable results were obtained when protein synthesis was inhibited with chloramphenicol. A glucose concentration of 0.1 per cent was found to permit polysaccharide synthesis to occur at a maximum rate. In the absence of exogenous carbohydrate, S. mitis catabolizes polysaccharide, and it is quantitatively converted to lactic acid. The acid formed was sufficient to lower the pH of packed cells of S. mitis to below pH 6, and to maintain it at this level for several hours in the presence of continuously flowing buffer of pH 7.0. In the absence of flowing buffer, the pH dropped below pH 5. The significance of these findings to acid production by dental plaque is discussed.
Publication Year: 1963
Publication Date: 1963-05-01
Language: en
Type: article
Indexed In: ['crossref', 'pubmed']
Access and Citation
Cited By Count: 69
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