Carbohydrates in Pooled Dental Plaque

Hotz, P; Guggenheim, B; Schmid, R

doi:10.1159/000259783

Cited by 104 publications

(58 citation statements)

References 19 publications

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“…This conclusion is confirmed by the fact that extensive washing of the stained biofilms resulted in nearly complete removal of the dye. In addition, the two streptococcal species present in our biofilm model produce large quantities of ␣(1-6)-and ␣(1-3)-linked glucans from sucrose (23). It is very likely (40), and 240K-PE (29).…”

Section: Discussionmentioning

confidence: 99%

Mass Transport of Macromolecules within an In Vitro Model of Supragingival Plaque

Thurnheer

Gmür

Shapiro

et al. 2003

Appl Environ Microbiol

138

129

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The aim of this study was to examine the diffusion of macromolecules through an in vitro biofilm model of supragingival plaque. Polyspecies biofilms containing Actinomyces naeslundii, Fusobacterium nucleatum, Streptococcus oralis, Streptococcus sobrinus, Veillonella dispar, and Candida albicans were formed on sintered hydroxyapatite disks and then incubated at room temperature for defined periods with fluorescent markers with molecular weights ranging from 3,000 to 900,000. Subsequent examination by confocal laser scanning microscopy revealed that the mean square penetration depths for all tested macromolecules except immunoglobulin M increased linearly with time, diffusion coefficients being linearly proportional to the cube roots of the molecular weights of the probes (range, 10,000 to 240,000). Compared to diffusion in bulk water, diffusion in the biofilms was markedly slower. The rate of diffusion for each probe appeared to be constant and not a function of biofilm depth. Analysis of diffusion phenomena through the biofilms suggested tortuosity as the most probable explanation for retarded diffusion. Selective binding of probes to receptors present in the biofilms could not explain the observed extent of retardation of diffusion. These results are relevant to oral health, as selective attenuated diffusion of fermentable carbohydrates and acids produced within dental plaque is thought to be essential for the development of carious lesions.The structure of microbial biofilms, consisting of single cells, cell aggregates, and microcolonies embedded in an exocellular polymeric hydrogel, has been the subject of intense experimental and theoretical scrutiny over the past decade (10,20,38,46). Biofilm anatomy and the physiological status of the cells contained within biofilms have profound consequences for clinical, industrial, and environmental microbiology. The exocellular space constitutes a primitive microcirculatory system that enables two-way transport between biofilm constituents and their surroundings and that facilitates intrabiofilm communication.Knowledge of the kinetics of mass transport within biofilms is essential for understanding how they achieve their characteristic architectures and for optimizing strategies to control or eradicate biofilms. Transport phenomena in biofilms have been studied by using microelectrodes (3, 41, 42) fiberoptic microsensors (2, 43), nuclear magnetic resonance spectroscopy (1, 52), infrared spectroscopy combined with Raman microscopy (47), fluorescence recovery after photobleaching (4, 5), fluorescence correlation spectroscopy (FCS) (18), and confocal laser scanning microscopy (CLSM) (11,25,26). Indirect methods predicated upon nuclear magnetic resonance spectroscopy, infrared spectroscopy-Raman microscopy, fluorescence recovery after photobleaching, FCS, or CLSM are preferred for measuring mass transport in biofilms, since invasive procedures (e.g., those involving microelectrodes or microsensors) are likely to compromise structural integrity and therefore perturb the del...

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Section: Discussionmentioning

confidence: 99%

Mass Transport of Macromolecules within an In Vitro Model of Supragingival Plaque

Thurnheer

Gmür

Shapiro

et al. 2003

Appl Environ Microbiol

138

129

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“…Most of the available evidence suggests that carbohydrates rather than nitrogen sources are the limiting nutrient for bacteria in dental plaque, although some controversy exists around this subject (12,21,44). However, during periods of dietary intake of carbohydrate, oral bacteria may experience nitrogen limitation.…”

Section: Discussionmentioning

confidence: 99%

Analysis of Urease Expression in Actinomyces naeslundii WVU45

Morou-Bermúdez

Burne

2000

Infect Immun

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The hydrolysis of urea by ureases of oral bacteria in dental plaque can cause a considerable increase in plaque pH, which can inhibit the development of dental caries. There is also indirect evidence that urea metabolism may promote the formation of calculus and that ammonia release from urea could exacerbate periodontal diseases. Actinomyces naeslundii, an early colonizer of the oral cavity and a numerically significant plaque constituent, demonstrates comparatively low levels of urease activity on isolation, so this organism has not been considered a major contributor to total oral urease activity. In this study it was observed that urease activity and urease-specific mRNA levels in A. naeslundii WVU45 can increase up to 50-fold during growth under nitrogen-limiting conditions. Using primer extension analysis, a putative, proximal, nitrogen-regulated promoter of the A. naeslundii urease gene cluster was identified. The functionality and nitrogen responsiveness of this promoter were confirmed using reporter gene fusions and 5 deletion analysis. The data indicated that regulation of urease expression by nitrogen availability in A. naeslundii may require a positive transcriptional activator. Plaque bacteria may experience nitrogen limitation when carbohydrates are present in excess. Therefore, based on the results of this study and in contrast to previous beliefs, strains of A. naeslundii may have the potential to be significant contributors to total plaque ureolysis, particularly during periods when there is an increased risk for caries development.

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“…The overproduction of GtfB could be advantageous to the organism for persistent colonization of tooth surfaces (3,31). Furthermore, mutant strains of S. mutans defective in gtfB are far less cariogenic than parent strains in vivo (38); a higher level of insoluble EPS in the matrix is associated with increased cariogenicity of biofilms in humans (17). Thus, the combination of starch and sucrose would result in a more virulent and more adherent biofilm.…”

mentioning

confidence: 99%

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

Klein

Duarte

Xiao

et al. 2009

Appl Environ Microbiol

136

200

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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.Oral diseases related to biofilms, such as dental caries, affect the majority of the world's population (27,34). Dental caries results from the interaction of specific bacteria and salivary constituents with dietary carbohydrates in the oral cavity; the appearance of biofilms on the tooth surface is the first clinical evidence of the diet-bacterium interaction. Sucrose is considered the "arch criminal" from the dietary standpoint because it is fermentable and also serves as a substrate for synthesis of extracellular polysaccharides (EPS) in dental biofilm (2, 28). Starches are an important source of fermentable carbohydrate and are usually consumed simultaneously with sucrose in modern societies. The combination of starch and sucrose is highly cariogenic in vivo (1, 10, 33) and may enhance the pathogenicity of biofilms in humans (30).Streptococcus mutans is a key contributor to the formation of cariogenic biofilms; this bacterium (i) synthesizes large amounts of extracellular glucans and fructans from sucrose using several glucosyltransferases (Gtfs) and a fructosyltransferase, (ii) adheres tenaciously to glucan-coated surfaces, and (iii) is highly acidogenic and acid tolerant, which are critical virulence properties in the pathogenesis of dental caries (2, 29, 31). Glucans provide specific binding sites for bacterial colonization on the tooth surface and bulk and structural integrity to the extracellular matrix; thus, they are essential for the formation and accumulation of dental biofilms (2). In addition, starches can be digested by ␣-amylases to maltose, maltodextrins, and other oligosaccharides, some of which can be acceptors during glucan synthesis by Gtfs (11,12,35). Starch hydrolysates produced by salivary ␣-amylases bound to saliva-coated hydroxyapatite (sHA) increased, in the presence of sucrose, the synthesis of structurally distinctive glucans by surface-adsorbed GtfB (35).Moreover, maltose and maltodextrins resulting from starch hydrolysis can be catabolized in acids by S. mutans (4). In this study, we investigated whether biochemical reactions involving interactions between specific host (␣-amylase) and bacterium-derived (Gtfs) enzymes and dietary carbohydrates (starch and sucrose) influence (i) the biochemical and structural properties of the EPS matrix and (ii) trigger specific adaptive responses by S. mutans at the transcriptional level, resulting in a biofilm with enhanced virulence.Biofilms of S. mutans UA159 (ϭ ATCC 700610) were formed using our amylase-active sHA disk model (18). Biofilms were grown in buffered tryptone yeast extract broth (pH 7.0) containing (i) 1% (wt/vol) starch (soluble starch [80% amylopectin a...

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Carbohydrates in Pooled Dental Plaque

Cited by 104 publications

References 19 publications

Mass Transport of Macromolecules within an In Vitro Model of Supragingival Plaque

Mass Transport of Macromolecules within an In Vitro Model of Supragingival Plaque

Analysis of Urease Expression in Actinomyces naeslundii WVU45

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

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