The activity of glucosyltransferase adsorbed onto saliva-coated hydroxyapatite

In vitro antimicrobial activity of propolis and Arnica montana against oral pathogens

Arnica and propolis have been used for thousands of years in folk medicine for several purposes. They possess several biological activities such as anti-inflammatory, antifungal, antiviral and tissue regenerative, among others. Although the antibacterial activity of propolis has already been demonstrated, very few studies have been done on bacteria of clinical relevance in dentistry. Also, the antimicrobial activity of Arnica has not been extensively investigated. Therefore the aim here was to evaluate in vitro the antimicrobial activity, inhibition of adherence of mutans streptococci and inhibition of formation of water-insoluble glucan by Arnica and propolis extracts. Arnica montana (10%, w/v) and propolis (10%, w/v) extracts from Minas Gerais State were compared with controls. Fifteen microorganisms were used as follows: Candida albicans--NTCC 3736, F72; Staphylococcus aureus--ATCC 25923; Enterococcus faecalis--ATCC 29212; Streptococcus sobrinus 6715; Strep. sanguis--ATCC 10556; Strep. cricetus--HS-6; Strep. mutans--Ingbritt 1600; Strep. mutans--OMZ 175; Actinomyces naeslundii--ATCC 12104, W 1053; Act. viscosus OMZ 105; Porphyromonas gingivalis; Porph. endodontalis and Prevotella denticola (the last three were clinical isolates). Antimicrobial activity was determined by the agar diffusion method and the zones of growth inhibition were measured. To assess cell adherence to a glass surface, the organisms were grown for 18 h at 37 degrees C in test-tubes at a 30 degree angle. To assay water-insoluble glucan formation, a mixture of crude glucosyltransferase and 0.125 M sucrose was incubated for 18 h at 37 degrees C in test-tubes at a 30 degree angle. Arnica and propolis extracts (20 microl) were added to these tubes to evaluate the % of inhibition of cell adherence and water-insoluble glucan formation. The propolis extract significantly inhibited all the microorganisms tested (p < 0.05), showing the largest inhibitory zone for Actinomyces spp. The Arnica extract did not demonstrate significant antimicrobial activity. Cell adherence and water-insoluble glucan formation were almost completely inhibited by the propolis extract at a final concentration of 400 microg/ml and 500 microg/ml, respectively. The Arnica extract showed slight inhibition of the adherence of the growing cells (19% for Strep. mutans and 15% for Strep. sobrinus) and of water-insoluble glucan formation (29%) at these same concentrations. Thus, the propolis extract showed in vitro antibacterial activity, inhibition of cell adherence and inhibition of water-insoluble glucan formation, while the Arnica extract was only slightly active in those three conditions.

Action of agents on glucosyltransferases from Streptococcus mutans in solution and adsorbed to experimental pellicle

Glucosyltransferase (Gtf) activity mediates sucrose-dependent adherence of mutans streptococci to the tooth surface, is essential for the cariogenicity of these micro-organisms, and contributes significantly to the exopolysaccharide component of the dental-plaque matrix. Clearly, agents that inhibit Gtfs could have therapeutic benefit. Here the effects of agents that inhibit Gtfs in solution and adsorbed to a surface were explored. Various classes of chemical reagents were tested for their ability to inhibit the enzymes responsible for insoluble-glucan synthesis (GtfB), insoluble/soluble glucan synthesis (GtfC), and soluble-glucan (GtfD) from Streptococcus mutans. Standard inhibition assays were done with Gtf enzyme in solution or with Gtf adsorbed to parotid saliva-coated hydroxylapatite (surface phase). Reagents tested included the metallic cations Li+, Zn2+, Cu2+, Fe2+ and Fe3+; the oxidizing compounds hypochlorite, Rose Bengal, perborate, and sodium-meta-periodate; and a panel of sugars and sugar analogues including sorbitol, xylitol, 1',4',6' trideoxy-trichloro-galactosucrose (TGS), and 1-deoxynojirimycin (dNJ). In solution, Gtf activity was inhibited significantly, at the highest concentrations tested: by the metal ions Zn2+, Cu2+, Fe2+ and Fe3+ (approx. 40-80% inhibition); by Rose Bengal and hypochlorite (approx. 80-90% inhibition); and by TGS and dNJ (approx. 50-80%). However, surface-adsorbed Gtfs displayed increased resistance to inhibition by the same metal cations and oxidizing compounds that inhibited them in solution. In contrast, both TGS and dNJ possessed similar inhibition profiles for both surface-bound Gtf and enzyme in solution. These data indicate that the nature of the inhibitor is important, and also whether the Gtf enzyme is in solution or adsorbed to saliva-coated hydroxylapatite.

Effect of IgA1 protease on the ability of secretory IgA1 antibodies to inhibit the adherence of Streptococcus mutans

Secretory IgA (SIgA) is the principal immunoglobulin isotype present in the mucosal secretions of humans. SIgA is thought to play a major role in host defense at these surfaces by inhibiting the colonization of potentially pathogenic microorganisms. A number of bacteria that are mucosal pathogens of humans produce a protease that specifically cleaves the IgA1 subclass of humans and great apes at the hinge region to produce Fab and Fc fragments. In order to study the effect of IgA1 protease on the ability of SIgA1 antibodies to inhibit bacterial adherence, an in vitro assay that quantifies the adsorption of radiolabeled Streptococcus mutans to hydroxyapatite (HA) beads was employed. High titer S. mutans-specific SIgA1 and SIgA2 antibodies were induced in chimpanzee milk for use in the assay. Fab alpha1 fragments had significantly reduced ability to inhibit adherence of S. mutans to saliva-coated HA compared to intact SIgA1 or SIgA2 anti-S. mutans antibodies. These data support the potential importance of IgA1 proteases as an ecological determinant in the oral cavity and their role as a determinant of pathogenesis of pathogenic bacteria whose portal of entry is the mucosal surface.

Binding properties of streptococcal glucosyltransferases for hydroxyapatite, saliva-coated hydroxyapatite, and bacterial surfaces

The binding specificities of Streptococcus glucosyltransferase (Gtf) B, C and D for hydroxyapatite (HA), saliva-coated hydroxyapatite (SHA), and bacterial surfaces were examined. For HA beads the following values were obtained: (K = affinity; N = number of binding sites) GtfB, K = 46 x 10(5) ml/mumol, N = 0.65 x 10(-6) mumol/m2; GtfC, K = 86 x 10(5) ml/mumol, N = 4.42 x 10(-6) mumol/m2.; GtfD, K = 100 x 10(5) ml/mumol, N = 0.83 x 10(-6) mumol/m2. For SHA beads, the following values were obtained: GtfB, K = 14.7 x 10(5) ml/mumol, N = 1.03 x 10(-6) mumol/m2; GtfC, K = 21.3 x 10(5) ml/mumol, N = 3.66 x 10(-6) mumol/m2; GtfD, K = 1.73 x 10(5) ml/mumol, N = 8.88 x 10(-6) mumol/m2. The binding of GtfB to SHA beads was reduced in the presence of parotid saliva, but the binding of GtfC and D was unaffected. The binding of GtfB to SHA in the presence of parotid saliva supplemented with GtfC and D was reduced when compared with its binding to SHA in the presence of parotid saliva alone. In contrast, te binding of GtfC and SHA was unaffected when parotid saliva was supplemented with the other Gtf enzymes. GtfB bound to several bacterial strains (Strep, mutans GS-5, Actinomyces viscosus OMZ105E and Lactobacillus casei 4646) in an active form, while GtfC and D did not bind to bacterial surfaces. It is concluded that of the three Gtf enzymes, GtfC has the highest affinity for HA and SHA surfaces and can adsorb on the the SHA surface in the presence of the other two enzymes. GtfD also binds to SHA in the presence of the other enzymes but has a very low affinity for the surface. GtfB does not bind to SHA in the presence of the other Gtf enzymes but binds avidly to bacterial surfaces in an active form. Therefore, GtfC most probably binds to apatitic surfaces, while GtfB binds to bacterial surfaces.

In vitro assessment of the antimicrobial activity of a local sustained release device containing amine fluoride for the treatment of oral infectious diseases

Dental caries and periodontal diseases are chronic infectious diseases caused by oral bacteria. Local sustained release delivery systems extend the time in which the drug is present in the oral cavity, thus enhancing its therapeutic potential while reducing its side effects. Amine-fluorides (AmF) are known anticaries agents and have recently been found to have an antibacterial effect against periodontal pathogens and caries-associated bacteria. The purpose of this in vitro study was to assess the antimicrobial activity of a local sustained release device (LSRD) containing AmF on Streptococcus sobrinus 6715. LSRD was prepared from an ethylcellulose matrix containing AmF. Release kinetics of AmF from the LSRD was measured simultaneously with its antimicrobial activity. The organic amine and the fluoride were released in different kinetics profiles: The fluoride was released faster than the organic amine. The antimicrobial activity of AmF was measured on planktonic bacteria in solution and on bacteria as part of experimental dental plaque. During a 10-day period, the concentration of the released AmF was above its MIC and no bacterial growth was observed. Bacterial counts in the dental plaque were reduced by 1 to 2 log units. Hence, the LSRD containing AmF has the potential to serve as a medicament in prevention and treatment of dental caries and periodontal diseases.

Antibacterial effect of chlorhexidine on bacteria adsorbed onto experimental dental plaque

The most common method used to examine the antibacterial effect of antiplaque agents is the minimal inhibitory concentration (MIC) method, which is tested on bacteria in suspensions. Examining the antibacterial effect on bacteria adsorbed onto dental surfaces models is not as popular, although it is clear that such models reflect the conditions in the oral cavity far more accurately than the conventional MIC method. The antibacterial effect of chlorhexidine (CHX) on bacteria adsorbed onto experimental dental plaque model was investigated. Hydroxyapatite beads were coated with human saliva. Next, cell-free fructosyltransferase (FTF) and glucosyltransferase (GTF) were adsorbed onto the beads, and sucrose was added to allow the synthesis of polysaccharide by the surface-bound enzymes. Following adsorption of Streptococcus sobrinus to the experimental dental plaque (EDP), the EDP was exposed to CHX at concentrations between 0.008 to 0.0002% at pH values of 5.5, 6.5, and 7.5. After 150 min incubation, growth of the adsorbed bacteria was measured by their incorporation of 3H-uridine or 3H-thymidine. Comparison of bacterial growth on the EDP with that in suspension showed that the surface-bound bacteria were less sensitive to CHX than were the bacteria in suspension. At all tested CHX concentrations, the antibacterial effect was independent of pH. In addition, under our experimental conditions, the use of 3H-uridine as an indicator of bacterial viability proved to be more sensitive than 3H-thymidine. The antibacterial effect of an agent in a model closely mimicking the tooth surface should generate results that are more relevant to the in vivo conditions than are conventional methods, thus bearing significant information concerning clinical applications of CHX.

Kinetic properties of glucosyltransferase adsorbed onto saliva-coated hydroxyapatite

Results from previous studies have shown that several properties of glucosyltransferase (GTF) adsorbed onto saliva-coated hydroxyapatite beads differ from those of GTF in solution. For example: thermostability, pH-activity dependency, sensitivity to inhibitors. The aim of this study was to compare the kinetics of the adsorbed GTF with its kinetic properties in solution. Hydroxyapatite beads were coated with human parotid saliva (sHA). Following washes, cell-free GTF enzyme from Streptococcus sobrinus 6715 (S. sobrinus 6715) or Streptococcus mutans GS-5 (S. mutans GS-5) was adsorbed onto sHA. The GTF-coated sHA were then incubated with radiolabeled sucrose for intervals of 5-360 minutes and the amount of glucans synthesized in situ by the adsorbed GTF was determined and compared with that produced in solution. The adsorbed GTF (from S. sobrinus 6715) exhibited a sharp increase in glucan production within the first 5 minutes of incubation while surface-bound GTF of S. mutans GS-5 displayed an initial burst of activity within the first 15 minutes of incubation. During the next 6 hours (duration of experiment) the amount of glucan on the beads did not increase with either enzyme. In contrast, the kinetic profile of the two GTFs in solution demonstrated a linear increase in the amount of glucans formed, with no initial burst effect. The results indicate that the rapid formation of glucans by GTF adsorbed onto sHA could have implications for colonization by oral microorganisms on tooth surfaces. The accelerated synthesis of glucan on tooth surfaces may affect the microbiology of the dental plaque, and might also influence the movement of substances, such as acids and antiplaque agents, across the acquired pellicle and dental plaque.

Interactions of streptococcal glucosyltransferases with alpha-amylase and starch on the surface of saliva-coated hydroxyapatite

The salivary pellicle consists of various proteins and glycoproteins which may interact with one another. Experiments were performed to elucidate the interactions of streptococcal glucosyltransferase (Gtf) enzymes with human salivary alpha-amylase in solution and on the surface of saliva-coated hydroxyapatite (SHA) beads. The Gtf enzymes -B, -C and -D, when immobilized on to SHA beads, reduced the activity of adsorbed amylase; GtfD showed the highest inhibition of salivary amylase activity. The presence of glucan produced by immobilized GtfD did not further reduce amylase activity. The amount of amylase adsorbed on to hydroxyapatite beads was reduced when salivary amylase was added simultaneously with any of the Gtf enzymes, suggesting that amylase and Gtfs may compete with each other for binding sites on hydroxyapatite. Starch hydrolysates produced by SHA-surface-bound salivary amylase were tested for their effect on glucan production from sucrose by Gtf enzymes in solution and on SHA beads; glucan production by SHA-immobilized GtfB was stimulated in the presence of starch hydrolysates. Glucan synthesized by SHA-immobilized GtfB in the presence of starch hydrolysates was less susceptible to hydrolysis by the fungal enzyme mutanase than was glucan made by SHA-immobilized GtfB in the absence of starch hydrolysates. Glucan production by GtfB associated with streptococci immobilized on to SHA was also enhanced in the presence of starch hydrolysates. The adhesion of oral micro-organisms to SHA coated with glucan made in the presence and absence of starch hydrolysates was investigated, and some bacteria displayed higher adhesion activities for the glucan made in the presence of the hydrolysates. Therefore, the interaction of amylase and Gtf enzymes on a SHA surface may modulate the formation of glucan and the adherence of oral micro-organisms.

Dental plaque as a biofilm

Dental plaque is the diverse microbial community found on the tooth surface embedded in a matrix of polymers of bacterial and salivary origin. Once a tooth surface is cleaned, a conditioning film of proteins and glycoproteins is adsorbed rapidly to the tooth surface. Plaque formation involves the interaction between early bacterial colonisers and this film (the acquired enamel pellicle). To facilitate colonisation of the tooth surface, some receptors on salivary molecules are only exposed to bacteria once the molecule is adsorbed to a surface. Subsequently, secondary colonisers adhere to the already attached early colonisers (co-aggregation) through specific molecular interactions. These can involve protein-protein or carbohydrate-protein (lectin) interactions, and this process contributes to determining the pattern of bacterial succession. As the biofilm develops, gradients in biologically significant factors develop, and these permit the co-existence of species that would be incompatible with each other in a homogenous environment. Dental plaque develops naturally, but it is also associated with two of the most prevalent diseases affecting industrialised societies (caries and periodontal diseases). Future strategies to control dental plaque will be targeted to interfering with the formation, structure and pattern of development of this biofilm.

Adhesion of actinomyces isolates to experimental pellicles

The ability of oral bacteria to adhere to surfaces is associated with their pathogenicity. Actinomyces can adhere to pellicle and cells through extracellular fimbriae. Research on adhesion of actinomyces has been conducted with use of hydroxyapatite (HA) coated with mammalian-derived salivary constituents, whereas the bacterial-derived components of the acquired pellicle have been largely ignored. The influence of the cell-free bacterial enzyme, glucosyltransferase (GTF), on adhesion of human and rodent isolates of Actinomyces viscosus was examined. Cell-free GTF was adsorbed onto parotid saliva-coated hydroxyapatite (sHA). Next, A. viscosus was exposed to the pellicle following the synthesis of glucan formed in situ by GTF. Glucans formed on the pellicle served as binding sites for adhesion of a rodent strain of A. viscosus. Conversely, the presence of in situ glucans on sHA reduced the adhesion of human isolates of A. viscosus compared with their adhesion to sHA. Adhesion of the rodent strains may be facilitated through a dextran-binding protein, since the rodent strains aggregated in the presence of dextrans and mutan. The human isolates were not aggregated by dextran or mutan. Pellicle harboring A. viscosus rodent strains interfered with the subsequent adhesion of Streptococcus mutans to the bacterial-coated pellicle. In contrast, the adhesion of S. mutans to pellicle was not decreased when the pellicle was pre-exposed to a human isolate of A. viscosus. The experimental data suggest that human and the rodent isolates of A. viscosus have distinct glucan adhesion properties.(ABSTRACT TRUNCATED AT 250 WORDS)

Identification of the adsorbing site of lysozyme onto the hydroxyapatite surface using hydrogen exchange and 1H NMR

The lysozyme-hydroxyapatite interaction was studied by measuring individual hydrogen-deuterium (H-D) exchange rates of amide protons. The H-D exchange reaction was initiated by transferring the lysozyme adsorbed on hydroxyapatite powder from H2O into D2O. After various H-D exchange time periods (pH 7.0, 25 degrees C), the complex was dissociated and the remaining hydrogen label was determined by 2D NMR analysis. The H-D exchange rate of amide protons of residues 9, 11, 13, and 83 was slowed in the hydroxyapatite-lysozyme complex compared with free lysozyme. Residues 9, 11 and 13 positioned at the back of the active site would be the location of the binding site.

Interactions of delmopinol with constituents of experimental pellicle

The prolonged retention of an effective chemotherapeutic agent on oral surfaces and in dental plaque aids in plaque control. The objective of this study was to investigate interactions between delmopinol, a morpholinoethanol derivative, and experimental pellicle. Hydroxyapatite beads were coated with different constituents of pellicle (e.g., saliva, carbohydrates, cell-free enzymes, and bacteria). Delmopinol demonstrated a higher affinity for saliva-coated hydroxyapatite (sHA) and for experimental pellicle coated with in situ-synthesized glucans than for untreated hydroxyapatite. High-molecular-weight (MW) dextran but not low-MW dextran interfered with the adsorption of delmopinol to sHA. Delmopinol did not compete with dextran for the same binding sites on sHA, nor did it compete with saliva for the same binding sites on untreated hydroxyapatite. Delmopinol inhibited the activity of cell-free fructosyltransferase adsorbed onto sHA. In addition, synthesis of glucans by Streptococcus mutans adsorbed onto sHA was significantly reduced in the presence of delmopinol.

Glucans synthesized in situ in experimental salivary pellicle function as specific binding sites for Streptococcus mutans

Many researchers have suggested that the role of glucan-mediated interactions in the adherence of Streptococcus mutans is restricted to accumulation of this cariogenic bacterium following its sucrose (i.e., glucan)-independent binding to saliva-coated tooth surfaces. However, the presence of enzymatically active glucosyltransferase in salivary pellicle suggests that glucans could also promote the initial adherence of S. mutans to the teeth. In the present study, the commonly used hydroxyapatite adherence assay was modified to include the incorporation of glucosyltransferase and the synthesis of glucans in situ on saliva-coated hydroxyapatite beads. Several laboratory strains and clinical isolates of S. mutans were examined for their ability to adhere to experimental pellicles, either with or without the prior formation of glucans in situ. Results showed that most strains of S. mutans bound stereospecifically to glucans synthesized in pellicle. Inhibition studies with various polysaccharides and fungal dextranase indicated that alpha 1,6-linked glucose residues were of primary importance in the glucan binding observed. Scanning electron microscopic analysis showed direct binding of S. mutans to hydroxyapatite surface-associated polysaccharide and revealed no evidence of trapping or cell-to-cell binding. S. mutans strains also attached to host-derived structures in experimental pellicles, and the data suggest that the bacterial adhesins which recognize salivary binding sites were distinct from glucan-binding adhesins. Furthermore, glucans formed in experimental pellicles appeared to mask the host-derived components. These results support the concept that glucans synthesized in salivary pellicle can promote the selective adherence of the cariogenic streptococci which colonize human teeth.

The effect of delmopinol on glucosyltransferase adsorbed on to saliva-coated hydroxyapatite

The aim was to explore the effects of delmopinol, a substituted amino-alcohol compound recently reported as a potential antiplaque agent, on GTF activity in solution and when adsorbed on to sHA. Delmopinol was without a significant effect on GTF activity in solution. In contrast, a reduction in the bound glucans synthesized by the adsorbed GTF was found in the presence of delmopinol. Delmopinol did not displace the adsorbed GTF from the sHA, nor was there significant desorption of glucans from sHA. The total glucan synthesis (bound and unbound) was reduced in the presence of delmopinol. Inhibition of GTF was not reversed by sucrose. Inhibition of GTF activity by delmopinol apparently results from drug-enzyme interaction on the surface of sHA beads. These observations provide further support for the important differences in the properties of adsorbed GTF and GTF in solution, illustrating that GTF-drug interaction differs between enzyme adsorbed to surfaces and enzyme in solution.

Role of a cell surface-associated protein in adherence and dental caries

Insertional inactivation of the Streptococcus mutans spaP gene was used to construct an isogenic mutant (834) of strain NG8 (serotype c) which lacked the major cell surface-associated protein referred to as P1 (15). Results of several studies suggest that P1 is involved in the adherence of S. mutans to saliva-coated apatite surfaces. With an in vitro model system of hydroxyapatite (HA) beads coated with parotid saliva (PS) and additional HA surfaces coated with PS and in situ-formed glucan, it was observed that mutant 834 adhered poorly to the PS/HA surfaces. In contrast, both parent and mutant strains bound to the PS-glucan/HA surface. Groups of intact and desalivated rats were infected with each strain to determine relative capacities to induce dental caries. Rats were fed a highly cariogenic diet containing 56% sucrose for 3 to 5 weeks. Each strain colonized the rodent model and caused similar levels of smooth-surface caries under these dietary conditions. It was concluded that P1 influences the ability of organisms to adhere to saliva-coated surfaces and possibly affects primary colonization of the oral cavity in the absence of a glucan surface but has no effect on glucan-mediated adherence in vitro or in vivo.

Enhancing the virulence of Streptococcus sobrinus in rats

The purpose of this study was to explore the virulence of strains of Streptococcus sobrinus that had been re-isolated from a desalivated rat. Furthermore, we wished to determine the influence of desalivation on the acidogenicity of fasting and sucrose-pulsed dental plaque in rats infected by strains of S. sorbrinus. Experimental groups were formed and infected as follows: Group 1, desalivated animals, S. sorbrinus ATCC27352; Group 2, intact animals, infected as in Group 1; Group 3, desalivated animals, S. sorbrinus re-isolated from a desalivated animal that had been infected with the ATCC 27352 strain for five weeks; Group 4, intact animals, infected as in Group 3; Group 5, desalivated animals, S. sobrinus re-isolated from a desalivated animal that had been infected with the ATCC27352 strain for ten weeks; Group 6, intact animals, infected as in Group 5; Group 7, intact animals, no infection. All animals were fed cariogenic diet 2000 and sucrose-sweetened drinking water ad libitum. After five weeks, desalivated and intact animals that had been infected with isolates obtained from desalivated animals had significantly higher (p less than 0.05) smooth-surface-caries scores than did intact and desalivated animals infected with cultures of the original stock ATCC strain. Moreover, fasting plaque pH values were statistically lower in desalivated animals (Groups 1 and 3) than in intact animals (Groups 2, 6, and 7) (Turkey analysis, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Why is sucrose so cariogenic? The role of glucosyltransferase and polysaccharides

Some aspects of the cariogenicity of sucrose are discussed, in particular the data indicating that glucosyltransferase (GTF) mediates the well known stickiness of sucrose exposed S. mutans and plaque in vivo. The non-sucrose dependent colonization of teeth, which has been studied extensively, is judged to be of less importance because S. mutans is only pathogenic in combination with sucrose. Strong evidence from several laboratories show that free GTF is present in saliva and that it adsorbs to the pellicle and is able to form glucan in the adsorbed state. Glucan-glucan interaction between 1-3 linked glucans gives a strong sucrose dependent interaction between glucan chains originating from the GTF adsorbed to the pellicle and from GTF on the bacterial surface.

Glucan-binding factor in saliva

High-molecular-weight polymers of alpha-1,6-linked D-glucans are insoluble in alcohol solutions. Whole, but not parotid, saliva prevented the precipitation of D-glucans by 80% (vol/vol) ethanol, showing that the whole saliva contained a factor which complexed with the glucan to render it alcohol soluble. The glucan-binding factor was retained on a column of Sephacryl S-200 which had been preequilibrated with 80% ethanol. The factor was then eluted with water. Passive hemagglutination assays revealed that the glucan-binding factor could sensitize erythrocytes to agglutination with anti-poly(glycerolphosphate), suggesting that the active glucan-binding component with lipoteichoic acid. The glucan-solubilizing factor was resistant to heat (100 degrees C), proteases, sialidase, lysozyme, lactoperoxidase, trichloroacetic acid, and Triton X-100. When sucrose was added to saliva, a suspension of Streptococcus cricetus AHT, or a suspension of Streptococcus sanguis 10556, relatively large amounts of glucan-binding factor were released in a soluble form. In addition, penicillin G caused the release of the glucan-solubilizing component from a suspension of S. cricetus AHT. It is suggested that whole saliva contains a component, tentatively identified as lipoteichoic acid, which can complex with glucans in a relatively hydrophobic solvent. This type of complex formation may be important in the adhesion of oral streptococci to saliva-coated surfaces.