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. 2009 Feb;75(3):837-41.
doi: 10.1128/AEM.01299-08. Epub 2008 Nov 21.

Structural and Molecular Basis of the Role of Starch and Sucrose in Streptococcus Mutans Biofilm Development

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Free PMC article

Structural and Molecular Basis of the Role of Starch and Sucrose in Streptococcus Mutans Biofilm Development

M I Klein et al. Appl Environ Microbiol. .
Free PMC article

Abstract

The interaction of sucrose and starch with bacterial glucosyltransferases and human salivary amylase may enhance the pathogenic potential of Streptococcus mutans within biofilms by influencing the structural organization of the extracellular matrix and modulating the expression of genes involved in exopolysaccharide synthesis and specific sugar transport and two-component systems.

Figures

FIG. 1.
FIG. 1.
(A) Water-insoluble glucans synthesized by S. mutans GtfB labeled with Alexa Fluor 647-dextran conjugate with a maximum absorbance wavelength of 647 nm and a maximum fluorescence emission wavelength of 668 nm. (Panel A-1) Phase-contrast image of glucans before excitation with a laser at 633 nm (20× oil objective; numerical aperture, 0.7). (Panel A-2) Fluorescence image of glucans. (B) S. mutans cells grown in culture medium containing 2.5 μM Alexa Fluor 647-dextran conjugate. (Panel B-1) Differential contrast image of bacterial cells. (Panel B-2) Bacterial cells with laser excitation at 633 nm for Alexa Fluor 647-dextran detection. (Panel B-3) Bacterial cells with laser excitation at 488 nm for SYTO 9 detection.
FIG. 2.
FIG. 2.
(A) Biofilm formation in the presence of sucrose plus starch. (Panel A-1) Distribution of bacteria and EPS in the biofilms. (Panel A-2) Representative three-dimensional images of the structural organization of the biofilms: rendered images of the outer layers of biofilms. Green, bacteria; red, EPS. (B) Biofilm formation in the presence of sucrose. (Panel B-1) Distribution of bacteria and EPS in the biofilms. (Panel B-2) Representative three-dimensional images of the structural organization of the biofilms: rendered images of the outer layers of biofilms. Green, bacteria; red, EPS.
FIG. 3.
FIG. 3.
Real-time PCR analysis of gtfB, gtfC, gtfD and dexA gene expression by S. mutans growing in the presence of sucrose or sucrose plus starch. The mRNA level of each gene in each sample was normalized to that of 16S rRNA. The values were then compared to those for sucrose-grown biofilms (which were assigned an arbitrary value of 1) to determine the change (fold) in gtf gene expression. The data are the means ± standard deviations for triplicate determinations in at least three separate experiments. An asterisk indicates that a value is significantly different from the value for the sucrose-grown biofilms (P < 0.05, Tukey's test).

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