Optimization of an hydroxyapatite adhesion assay for Streptococcus sanguis

Casein phosphopeptide combined with fluoride enhances the inhibitory effect on initial adhesion of Streptococcus mutans to the saliva-coated hydroxyapatite disc

Background

Recent preventive strategies for dental caries focus on targeting the mechanisms underlying biofilm formation, including the inhibition of bacterial adhesion. A promising approach to prevent bacterial adhesion is to modify the composition of acquired salivary pellicle. This in vitro study investigated the effect and possible underlying mechanism of pellicle modification by casein phosphopeptide (CPP) on Streptococcus mutans (S. mutans) initial adhesion, and the impact of fluoride on the efficacy of CPP.

Methods

The salivary pellicle-coated hydroxyapatite (s-HA) discs were treated with phosphate buffered saline (negative control), heat-inactivated 2.5% CPP (heat-inactivated CPP), 2.5% CPP (CPP) or 2.5% CPP supplemented with 900 ppm fluoride (CPP + F). After cultivation of S. mutans for 30 min and 2 h, the adherent bacteria were visualized by scanning electron microscopy (SEM) and quantitatively evaluated using the plate count method. Confocal laser scanning microscopy (CLSM) was used to evaluate the proportions of total and dead S. mutans. The concentrations of total, free, and bound calcium and fluoride in the CPP and fluoride-doped CPP solutions were determined. The water contact angle and zeta potential of s-HA with and without modification were measured. The data were statistically analyzed using one-way ANOVA followed by a Turkey post hoc multiple comparison test.

Results

Compared to the negative control group, the amount of adherent S. mutans significantly reduced in the CPP and CPP + F groups, and was lowest in the CPP + F group. CLSM analysis showed that there was no statistically significant difference in the proportion of dead S. mutans between the four groups. Water contact angle and zeta potential of s-HA surface significantly decreased in the CPP and CPP + F groups as compared to the negative control group, and both were lowest in the CPP + F group.

Conclusions

Pellicle modification by CPP inhibited S. mutans initial adhesion to s-HA, possibly by reducing hydrophobicity and negative charge of the s-HA surface, and incorporating fluoride into CPP further enhanced the anti-adhesion effect.

Calcium Modulates Interactions between Bacteria and Hydroxyapatite

Bacterial adhesion onto hydroxyapatite is known to depend on the surface properties of both the biomaterial and the bacterial strain, but less is known about the influence of the composition of the aqueous medium. Here, the adhesion of Streptococcus mutans and 3 different Lactobacilli on powdered hydroxyapatite was shown to change with Ca2+ concentration. The effect depends on the surface properties of each strain. Adhesion of Lactobacillus fermentum and salivarius (and of Streptococcus mutans at low Ca2+) was enhanced with increasing Ca2+ concentration. Lactobacillus casei was efficiently removed by adhesion on hydroxyapatite, even without Ca2+ addition, and the effect of this ion was only marginal. The results are interpreted in terms of Ca2+-mediated adhesion, and relative to the hydrophobic properties of each strain and the electrical properties of the bacterial and solid surfaces (electrophoretic mobility).

Identification of ssDNA aptamers specific to clinical isolates of Streptococcus mutans strains with different cariogenicity

Streptococcus mutans, a Gram-positive facultative anaerobic bacterium, is considered to be a major etiological factor for dental caries. In this study, plaques from dental enamel surfaces of caries-active and caries-free individuals were obtained and cultivated for S. mutans isolation. Morphology examination, biochemical characterization, and polymerase chain reaction were performed to identify S. mutans The cariogenicity of S. mutans strains isolated from clinical specimens was evaluated by testing the acidogenicity, aciduricity, extracellular polysaccharide production, and adhesion ability of the bacteria. Finally, subtractive SELEX (systematic evolution of ligands by exponential enrichment) technology targeting whole intact cells was used to screen for ssDNA aptamers specific to the strains with high cariogenicity. After nine rounds of subtractive SELEX, sufficient pool enrichment was achieved as shown by radioactive isotope analysis. The enriched pool was cloned and sequenced randomly, followed by MEME online and RNA structure software analysis of the sequences. Results from the flow cytometry indicated that aptamers H1, H16, H4, L1, L10, and H19 could discriminate highly cariogenic S. mutans strains from poorly cariogenic strains. Among these, Aptamer H19 had the strongest binding capacity with cariogenic S. mutans strains with a dissociation constant of 69.45 ± 38.53 nM. In conclusion, ssDNA aptamers specific to highly cariogenic clinical S. mutans strains were successfully obtained. These ssDNA aptamers might be used for the early diagnosis and treatment of dental caries.

Reduced adhesion of oral bacteria on hydroxyapatite by fluoride treatment

The mechanisms of action of fluoride have been discussed controversially for decades. The cavity-preventive effect for teeth is often traced back to effects on demineralization. However, an effect on bacterial adhesion was indicated by indirect macroscopic studies. To characterize adhesion on fluoridated samples on a single bacterial level, we used force spectroscopy with bacterial probes to measure adhesion forces directly. We tested the adhesion of Streptococcus mutans , Streptococcus oralis , and Staphylococcus carnosus on smooth, high-density hydroxyapatite surfaces, pristine and after treatment with fluoride solution. All bacteria species exhibit lower adhesion forces after fluoride treatment of the surfaces. These findings suggest that the decrease of adhesion properties is a further key factor for the cariostatic effect of fluoride besides the decrease of demineralization.

Role of Streptococcus sanguinis sortase A in bacterial colonization

Streptococcus sanguinis, a normal inhabitant of the human oral cavity, has low cariogenicity, though colonization on tooth surfaces by this bacterium initiates aggregation by other oral bacteria and maturation of dental plaque. Additionally, S. sanguinis is frequently isolated from infective endocarditis patients. We investigated the functions of sortase A (SrtA), which cleaves LPXTG-containing proteins and anchors them to the bacterial cell wall, as a possible virulence factor of S. sanguinis. We identified the srtA gene of S. sanguinis by searching a homologous gene of Streptococcus mutans in genome databases. Next, we constructed an srtA-deficient mutant strain of S. sanguinis by insertional inactivation and compared it to the wild type strain. In the case of the mutant strain, some surface proteins could not anchor to the cell wall and were partially released into the culture supernatant. Furthermore, adherence to saliva-coated hydroxyapatite beads and polystyrene plates, as well as adherence to and invasion of human epithelial cells were reduced significantly in the srtA-deficient strain when compared to the wild type. In addition, antiopsonization levels and bacterial survival of the srtA-deficient mutant were decreased in human whole blood. This is the first known study to report that SrtA contributes to antiopsonization in streptococci. Our results suggest that SrtA anchors surface adhesins as well as some proteins that function as antiopsonic molecules as a means of evading the human immune system. Furthermore, they demonstrate that SrtA of S. sanguinis plays important roles in bacterial colonization.

Oral microbial communities: biofilms, interactions, and genetic systems

Oral microbial-plaque communities are biofilms composed of numerous genetically distinct types of bacteria that live in close juxtaposition on host surfaces. These bacteria communicate through physical interactions called coaggregation and coadhesion, as well as other physiological and metabolic interactions. Streptococci and actinomyces are the major initial colonizers of the tooth surface, and the interactions between them and their substrata help establish the early biofilm community. Fusobacteria play a central role as physical bridges that mediate coaggregation of cells and as physiological bridges that promote anaerobic microenvironments which protect coaggregating strict anaerobes in an aerobic atmosphere. New technologies for investigating bacterial populations with 16S rDNA probes have uncovered previously uncultured bacteria and have offered an approach to in situ examination of the spatial arrangement of the participant cells in oral-plaque biofilms. Flow cells with saliva-coated surfaces are particularly useful for studies of biofilm formation and observation. The predicted sequential nature of colonization of the tooth surface by members of different genera can be investigated by using these new technologies and imaging the cells in situ with confocal scanning laser microscopy. Members of at least seven genera now can be subjected to genetic studies owing to the discovery of gene-transfer systems in these genera. Identification of contact-inducible genes in streptococci offers an avenue to explore bacterial responses to their environment and leads the way toward understanding communication among inhabitants of a multispecies biofilm.

Dental plaque formation

Dental plaque is a complex biofilm that accumulates on the hard tissues (teeth) in the oral cavity. Although over 500 bacterial species comprise plaque, colonization follows a regimented pattern with adhesion of initial colonizers to the enamel salivary pellicle followed by secondary colonization through interbacterial adhesion. A variety of adhesins and molecular interactions underlie these adhesive interactions and contribute to plaque development and ultimately to diseases such as caries and periodontal disease.

Tenacious adhesion of Actinobacillus actinomycetemcomitans strain CU1000 to salivary-coated hydroxyapatite

Adherence of Actinobacillus actinomycetemcomitans to hard-tissue surfaces was evaluated by comparing a phenotypically stable, well-maintained clinical isolate (strain CU1000) to Streptococcus gordonii G9B, an extensively studied oral-colonizing bacterium. Standard innocula of radiolabelled bacteria were added to saliva-coated hydroxyapatite (SHA) and the ratio of bound to unbound cells counted. Several other clinical isolates as well as laboratory strain Y4 were studied. In other experiments, cell detachment from SHA was compared in static and shaking vessels to calculate controlled desorption of cells over time. A sonic-displacement assay was used to measure avidity of binding to HA and SHA. To better define the attachment properties of CU1000, bacteria were treated with a variety of agents including detergents, salts and enzymes before or after incubation with SHA. Results indicated that CU1000 bound better than G9B (a minimum of 10-fold greater; p < or = 0.05) and did not desorb from SHA, while G9B desorbed to equilibrium in 4 h. Furthermore, Langmuir isotherm calculations indicated that, unlike G9B, CU1000 did not follow second-order adsorption kinetics and thus did not achieve saturation. In addition, of the agents tested only periodate reduced attachment and resulted in detachment of CU1000 from surfaces. These experiments suggest that clinical isolates of A. actinomycetemcomitans possess unique binding properties that promote adsorption to and impede desorption from SHA. The characteristics described for the actinobacillus in this study have been previously underestimated, appear to be mediated by glycoconjugates, and may resemble attachment described for several biofilm-forming, non-oral pathogens.

Biofilm formation by Porphyromonas gingivalis and Streptococcus gordonii

Confocal scanning laser microscopy (CSLM) was used to visualize and quantify biofilm formation by the oral bacteria Streptococcus gordonii and Porphyromonas gingivalis. A saliva-coated glass coverslip under continuous bacterial challenge and conditions of low shear force was used to investigate attachment to the salivary pellicle and also the effect of cell-cell interactions on the extent of colonization and biofilm development. S. gordonii bound to the salivary pellicle and outcompeted P. gingivalis for attachment sites. Both P. gingivalis and S. gordonii failed to establish substantial biofilm formation independently. However, biofilm formation did occur subsequent to initial adherence of P. gingivalis to S. gordonii cells deposited on the salivary pellicle. The commensal species S. gordonii may, therefore, provide an attachment substrate for colonization and biofilm accretion by the potential pathogen, P. gingivalis.

scbA from Streptococcus crista CC5A: an atypical member of the lraI gene family

A new member of the lraI family of putative adhesin genes was cloned, from Streptococcus crista CC5A, and sequenced. The gene, scbA appears to be part of an ABC transport operon and encodes a putative peptide of 34.7 kDa. The protein contains a signal sequence with residues 17 to 21 (L-A-A-C-S) matching the consensus sequence for the prolipoprotein cleavage site of signal peptidase II. ScbA is 57 to 93% identical, at the amino acid level, with the five previous sequenced members of the LraI family. Surprisingly, ScbA does not exhibit adhesion properties characteristic of the other LraI proteins. Strain CC5A bound poorly to saliva-coated hydroxyapatite and did not coaggregate with Actinomyces naeslundii PK606. An scbA insertion-duplication mutation that abolished expression (of ScbA was created. There was no difference in fibrin binding between this mutant and wild-type CC5A. Since it is possible that ScbA could play a role in corncob formation between S. crista and Fusobacterium nucleatum, this property was examined. The mutant strain retained the ability to form corncobs. On the basis of the lack of adhesin properties it appears that ScbA is an atypical member of the LraI family.

Inactivation of the gene encoding surface protein SspA in Streptococcus gordonii DL1 affects cell interactions with human salivary agglutinin and oral actinomyces

Cell surface protein SSP-5 in the oral bacterium Streptococcus gordonii M5 binds human salivary agglutinin in a Ca(2+)-dependent reaction (D.R. Demuth, E.E. Golub, and D. Malamud, J. Biol. Chem. 265:7120-7126, 1990). The region of the gene encoding an N-terminal segment of a related polypeptide (SspA) in S. gordonii DL1 (Challis) was isolated following polymerase chain reaction amplification of genomic DNA. The sspA gene in S. gordonii DL1 was insertionally inactivated by homologous recombination of the erythromycin resistance (Emr) determinant ermAM onto the streptococcal chromosome. The SspA polypeptide (apparent molecular mass, 210 kDa) was detected on Western blots (immunoblots) of spheroplast extracts and extracellular culture medium proteins from wild-type strain DL1 but was absent from Emr mutants. One SspA- mutant (designated OB220) was not altered in rate or extent of aggregation by whole saliva or parotid saliva but showed reduced aggregation in the presence of purified salivary agglutinin. Mutant bacteria were unaffected in their ability to adhere to hydroxylapatite beads coated with whole or parotid saliva and were unaltered in cell surface hydrophobicity. However, the SspA- strain OB220 was deficient in binding salivary agglutinin and in binding to six strains of Actinomyces naeslundii. Therefore, expression of SspA polypeptide in S. gordonii is associated with both agglutinin-dependent and agglutinin-independent aggregation and adherence reactions of streptococcal cells.

Protein composition, adhesion, and agglutination properties of saliva in burning mouth syndrome

Resting and stimulated whole saliva and parotid saliva of men and pre- and post-menopausal women with burning mouth syndrome (BMS) and their matched controls were studied. Women with BMS had slightly, but not significantly, higher flow rates than their controls. The total protein concentration in stimulated saliva of women with BMS was significantly lower than that of controls. This difference was not associated with the flow rate. The proportional amount of sialic acid, used as an indicator of mucin concentration, was higher in subjects with BMS than in their controls. SDS-PAGE showed no consistent differences in the protein profiles of saliva, nor were any differences observed in the adhesion or agglutination assays between subjects with BMS and their matched controls. Thus, the present results indicate that BMS is not associated with a decrease in the protecting and lubricating properties of saliva.

Molecular characterization of a negative regulator of Streptococcus sobrinus surface protein antigen gene

Mutans streptococci have been shown to give rise to variants in terms of expression of surface protein antigens by repeated subculturing of the organisms, which in turn induces changes in colonial morphologies. A 2,850-bp upstream region of the gene (pag) for a surface protein antigen, PAg, of Streptococcus sobrinus MT3791 was determined. Analysis of the nucleotide sequence revealed the existence of three open reading frames (ORFs) located upstream of the pag gene. ORF1 extended from an undetermined further upstream sequence to the termination codon TAG lying 1,943 bp upstream of the pag gene. ORF2, consisting of 609 bp lying 1,689 bp upstream of the pag gene, encoded a protein of 23,347 Da and a protein of 22,792 Da. The synthesis of these proteins (protein antigen regulators) was demonstrated by using the in vitro T7 RNA polymerase/promoter system. ORF3, extending from 314 bp upstream of the pag gene to 712 bp upstream of the pag gene, encoded a protein of 14,802 Da. Disruption of chromosomal ORF2 of parent strain MT3791 by allelic exchange resulted in isogenic mutants, termed PAREm-1 and PAREm-2, that synthesized larger amounts of cell-free and cell-associated PAg than did the parent strain. RNA dot blot analysis demonstrated that expression of PAg-specific mRNA transcripts by mutants PAREm-1 and PAREm-2 was about 32-fold higher than that by strain 3791. Mutants PAREm-1 and PAREm-2 were found to be more hydrophobic than strain MT3791. Resting cells of these mutants attached in larger numbers to saliva-coated hydroxyapatite than did those of the parent strain. These results suggest that protein antigen regulator regulates the expression of PAg gene in a negative fashion, affecting the colonization of tooth surfaces by the organism. Thus, ORF2 is concluded to be a negative regulator gene of PAg synthesis and was designated par.

Interactions of Actinomyces naeslundii strains T14V and ATCC 12104 with saliva, collagen and fibrinogen

Approximately similar numbers of actinomyces cells adhered to hydroxylapatite beads coated with saliva, collagen or fibrinogen. Adherence generally was unaffected by the presence of free saliva. Binding of cells to collagen- or fibrinogen-coated beads was reduced in the presence of either free collagen or fibrinogen. Glucan inhibited bacterial adherence only to collagen-coated hydroxylapatite beads. It is suggested that actinomyces bind to saliva-, collagen- or fibrinogen-coated surfaces by different mechanisms, but that these mechanisms involve some common bacterial cell-surface components.

An in vitro method to study the adherence of bacteria to saliva-treated tooth enamel sections

An in vitro bacterial adherence assay which employed human tooth enamel sections precoated with saliva and an epifluorescent staining technique with acridine orange was developed. The assay was used to study the adherence properties of fresh and type strains of the following oral bacterial species: Bacteroides gingivalis, Bacteroides intermedius, Capnocytophaga species, Haemophilus aphrophilus, Actinobacillus actinomycetemcomitans, Peptostreptococcus species, Veillonella species, Actinomyces israelii, Streptococcus salivarius and Streptococcus sanguis. Approximately half of the bacteria tested adhered well to enamel, including the fresh isolates of B. gingivalis, B. intermedius, Veillonella species and S. sanguis. Adherence did not correlate in all cases with the known distribution of these species in vivo. Three-quarters of the fresh strains adhered better than the type strains of the same species. The assay method is an alternative to the widely used hydroxyapatite bead assay.

Surface hydrophobicity, adherence, and aggregation of cell surface protein antigen mutants of Streptococcus mutans serotype c

The pac gene of the serotype c strain Streptococcus mutans MT8148 encodes a cell surface protein antigen (PAc) of approximate 190 kilodaltons. The serotype c strain S. mutans GS-5 does not produce the 190-kilodalton PAc but produces a lower-molecular-weight protein that reacts with anti-PAc serum. The SphI-BamHI fragment of the pac gene was ligated with the S. mutans-Escherichia coli shuttle vector pSA3. The chimeric shuttle vector was transformed into strain GS-5, and two transformants (TK15 and TK18) were isolated. These transformants produced a large amount of cell-free and cell-bound PAc of 190 kilodaltons. No plasmid was isolated from these transformants, and the EcoRI fragments of their chromosomal DNA hybridized with the erythromycin resistance gene in the shuttle vector DNA, indicating insertion of the chimeric shuttle vector DNA into the chromosomal DNA. The cell hydrophobicity of strains TK15 and TK18 as well as PAc-defective mutants constructed by inserting an erythromycin resistance gene into the pac gene of strain MT8148 was analyzed. Strains MT8148, TK15, and TK18 were hydrophobic. On the other hand, strain GS-5 and PAc-defective MT8148 transformants were hydrophilic. Resting cells of the hydrophobic strains attached in larger numbers to saliva-coated hydroxyapatite than did the hydrophilic strains. Human whole saliva induced the aggregation of cells of the hydrophobic strains but not that of cells of the hydrophilic strains. These results suggest that cell surface PAc of S. mutans serotype c participates in attachment of the streptococcal cell to experimental pellicles.

A transmission electron microscopy study of the adsorption patterns of early developing artificial pellicles on human enamel

Adsorption patterns of pellicles formed in a flow cell system under a moderate shear rate of 21 s-1, were studied with a replica technique. Characteristic features of the bare enamel surface disappeared within seconds after exposure to reconstituted saliva, indicating the adsorption of a homogeneous film. After that, three to four distinct homogeneous films were adsorbed on top of each other within 10 s and an uneven, knotted structure developed with stalky projections on the outer surface. This heterogeneous adsorption pattern determined the structure of the pellicle surface for at least 2 h.

Effect of zeta potential and surface energy on bacterial adhesion to uncoated and saliva-coated human enamel and dentin

Physicochemical surface characteristics of early plaque-forming bacteria and of human tooth surfaces were measured to establish their role in bacterial adhesion to intact dental tissue slabs. In addition, the influence of an experimental salivary pellicle was evaluated. Strains of S. mutans, S. sanguis, S. salivarius, A. viscosus, and A. odontolyticus showed relatively high surface free energies (range, 99-128 mJ.m-2) and carried a negative surface charge, at both physiological (mu = 0.057) and low (mu = 0.020) ionic strengths of the medium. Very large differences in hydrophobicity were detected when the hexadecane adsorption test was used for measurement. Powdered enamel and dentin were also negatively charged at low ionic strength but were slightly positively charged in the physiological buffer. The surface free energy of enamel and dentin increased upon saliva coating, whereas the surface charge was always negative. The adhesion experiments showed: (1) large differences in the binding of various bacteria to the same surface; (2) an up to 20-fold difference in the binding of the same bacterium to different surfaces, although the binding of some strains was relatively independent of the type of surface or presence of a salivary pellicle; (3) a significant decrease in adhesion when the ionic strength of the medium was lowered, due to increased electrostatic repulsion (however, the adhesion of some bacteria was independent of the ionic strength of the medium); (4) different time-dependent adherence kinetics, depending on both the bacteria and nature of the solid surface; and (5) a propensity for plaque streptococci to bind to uncoated dentin.

Electron-microscopic observation of adherence of serotype c Streptococcus mutans to the enamel surface due to glucan synthesis

Cellular adherence of three strains with water-insoluble glucan (IG)-synthesizing ability and a strain lacking the ability of serotype c Streptococcus mutans to the saliva-coated human enamel surface was examined by scanning (SEM) and transmission (TEM) electron-microscopy. SEM revealed that organisms of all strains used adhered directly to the enamel surface in the absence of sucrose. Cell-to-cell attachment was scarcely observed in the absence of sucrose. Cell-to-cell attachment via amorphous substance on the cell surface was observed by SEM when the strains with IG-synthesizing ability were incubated with the saliva-coated enamel in the presence of sucrose. TEM revealed that cell-associated enzymes of these strains synthesized filamentous and double-stranded fibrillar structures from sucrose. The strain lacking IG-synthesizing ability was unable to induce cell-to-cell attachment in the presence of sucrose, nor was it able to synthesize the amorphous substance. These results indicate that production of IG by cell-associated glucosyltransferase participates in cellular accumulation of serotype c S. mutans.

Characterization of an adhesion antigen of Streptococcus sanguis G9B

An antigen possessing the attributes of an adhesion has been identified in Streptococcus sanguis G9B. Cell surface components were extracted from G9B and a spontaneously occurring nonadherent mutant of G9B, strain Adh-, with a 2 mM barbital buffer, pH 8.6. The extract of G9B but not of Adh- absorbed more than 80% of the adhesion-inhibitory activity of anti-G9B immunoglobulin G (IgG). Immunoblots revealed 80- and 52-kilodalton (kDa) antigens present in the G9B extract but not in the Adh- extract. Absorption of anti-G9B IgG with Adh- and G9B barbital extracts showed a correlation between the loss of the 80- and 52-kDa antibodies and the loss of adhesion-inhibitory activity. An antibody prepared against the 80-kDa antigen excised from sodium dodecyl sulfate-polyacrylamide gels recognized the 80- and 52-kDa antigens and another antigen of 62 kDa but did not inhibit adhesion. However, an antibody from an electroblot containing the native protein from which the 80-kDa and related antigens were derived (the 80-kDa antigen complex) inhibited adhesion to the same extent as anti-G9B IgG. Periodate oxidation of the G9B barbital extract modified the 80-kDa antigen complex and resulted in the loss of 40% of its absorbing activity. The barbital extract also contained an endogenous enzyme responsible for producing the 62- and 52-kDa antigens from the 80-kDa protein and which, under optimal conditions, degraded the antigen completely, resulting in the loss of antibody-absorbing activity. The 80-kDa antigen complex has a molecular mass of more than 200 kDa in native polyacrylamide gels and a pI of 4.1 to 4.8. These observations suggest that the adhesion antigen in S. sanguis G9B is a large glycoprotein from which an 80-kDa antigen complex is derived.

Streptococcus sanguis surface antigens and their interactions with saliva

Saliva-binding molecules of Streptococcus sanguis and their receptors were investigated. Streptococcal cell surfaces were extracted with a barbital buffer and examined immunochemically. Strains G9B and Blackburn, which adhere specifically to saliva-coated hydroxyapatite via immunologically related adhesins, possess 80-, 62-, and 52-kilodalton (kDa), and 52-, 42-, and 29-kDa polypeptides, respectively, which correlate with adhesion to saliva-coated hydroxyapatite. Nonadherent strains Adh- and M-5 lack these antigens. In an immunoblot overlay, the putative adhesins bound to a 73-kDa receptor present in submandibular saliva but not in parotid saliva. G9B also contains a 160-kDa surface protein which bound to an unidentified receptor in both submandibular and parotid saliva samples. Blackburn barbital-extracted components bound to 78- and 70-kDa receptors in parotid saliva. These bacterial-salivary interactions may be important in the regulation of oral ecology.

Albumin as a blocking agent in studies of streptococcal adsorption to experimental salivary pellicles

A procedure involving blocking with bovine albumin was useful for differentiating between streptococcal interactions with components of experimental salivary pellicles similar to those which form on teeth and potential interactions with uncoated areas of mineral.