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PubMed1980

Specific inhibition of glucosyltransferase of Streptococcus mutans.

Clinical dextran, partially oxidized with sodium periodate, acts as a potent inhibitor of the extracellular glucosyltransferases of several cariogenic strains of oral Streptococcus mutans. Preincubation with oxidized dextran resulted in a rapid loss of up to 80% of the ability of the enzyme preparation to synthesize polysaccharide from sucrose, but there was no loss of enzyme activity when the oxidized dextrans were reduced with sodium borohydride before preincubation with enzyme. The presence of unoxidized clinical dextran during the preincubation period afforded the enzymes protection against inhibition by partially-oxidized dextran, but clinical dextran did not readily restore activity when it was added after incubation of the enzyme with oxidized polysaccharide. Fructosyltransferase, and glycogen and starch phosphorylase, activities were not inhibited by oxidized dextran, and the bacterial glucosyltransferases were not inhibited by partially oxidized glycogen and amylose. It is proposed that the potent and specific inhibition of glucosyltransferase by oxidized dextran results from the interaction of dialdehyde groups with reactive functional groups close to the dextran-binding site of the enzyme.

Animals↗

PubMed1979

Antigens of Streptococcus mutans: cellular localization of the serotype-specific polysaccharide of strain AHT and release during exponential growth.

The serotype-specific polysaccharide of Streptococcus mutans AHT (serotype a) was shown to be loosely associated with the cell surface of this organism. The antigen was extracted from whole cells by boiling in sodium acetate buffer, pH 4.0, for 10 min. The purified product was found to be a diheteroglycan of galactose and glucose (3.6:1, molar ratio). The antigen possessed serological characteristics similar to the a antigen previously extracted from purified cell walls with hot formamide. Its physicochemical structure was identical to the previously studied wall antigen. Electron micrographs, developed after immunocytological labeling of this antigen on whole cells, revealed it to compose a dense microcapsule surrounding the microbe. Analyses of spent culture fluids indicated that the antigen was released during exponential growth at a rate directly proportional to the increase in culture biomass. It is concluded that the serotype-specific antigen may be a prime immunogen due to its surface localization at both capsule and wall sites.

Antigens, Bacterial↗

PubMed1984

Effect of fluoride on growth and acid production by Streptococcus mutans in dental plaque.

The aim of this study was to measure the effect of fluoride on the production of organic acids by Streptococcus mutans in dental plaque. The effect was studied in a simplified model of dental plaque with gnotobiotic rats monoinfected with S. mutans Ny341. Adaptation of S. mutans to fluoride was induced by feeding one group of the rats on fluoride-containing diet and drinking water. No difference was found in the accumulation of S. mutans on the teeth between the fluoride-adapted and the control groups. However, there was a significant difference in the amount of lactic acid in metabolically resting plaque between the groups, lactic acid being lower in the fluoride-adapted plaque. At 5 min after a rinse containing 10% sucrose, a high level of lactic acid was found in plaque from animals not exposed to fluoride. Rinses containing 4 or 20 mM fluoride before the sucrose rinse significantly inhibited the lactic acid production in the control group. In the plaque from rats on fluoridated diet and drinking water the sucrose-induced production of lactic acid was not inhibited by a 4 mM fluoride rinse. Moreover, the production of lactic acid in the fluoride-adapted plaque was prolonged. The results indicate that due to fluoride adaptation the inhibition of acid production is unlikely to be important for the caries-preventive action of fluoride.

Acetates↗

PubMed1994

Oral immunization of humans with dehydrated liposomes containing Streptococcus mutans glucosyltransferase induces salivary immunoglobulin A2 antibody responses.

Seven healthy adult volunteers each ingested an enteric-coated capsule containing 500 micrograms of Streptococcus mutans glucosyltransferase (GTF) in dehydrated liposomes for 3 consecutive days. The immunization regimen was repeated 28 days later. Parotid saliva and plasma were collected prior to and at a weekly interval for 8 weeks following the first immunization for analysis of anti-GTF activity by enzyme-linked immunosorbent assay. The levels of immunoglobulin A1 (IgA1) and IgA2 anti-GTF activities increased in the parotid saliva from 5 of 7 individuals after immunization. Increases in the mean level of IgA1 and IgA2 anti-GTF responses peaked on day 35 (77% and 175% increase over baseline, respectively), although variation was noted in the kinetics and subclass of responses between individuals. No salivary IgG or IgM responses were observed. Low plasma IgM, IgG and IgA anti-GTF responses were seen in immunized subjects. Oral immunization with a dehydrated liposome-protein vaccine was effective in inducing a secretory IgA antibody response, which was primarily of the IgA2 subclass. These results provide the first evidence for the use an oral dehydrated liposome-protein vaccine in humans.

Administration, Oral↗

PubMed1976

Epidemiological survey of Streptococcus mutans among Japanese children. Identification and serological typing of the isolated strains.

An epidemiological investigation was carried out to identify and determine the serotypes of Streptococcus mutans from carious lesions of young Japanese children. For this purpose, a direct fluorescent antibody technique was mainly used. Fluorescein isothiocyanate-conjugated antibodies were prepared for the five known serotypes of S. mutans. Cross reactions and nonspecific reactions were eliminated by adsorption, counterstaining, or DEAE-cellulosecolumn chromatography. Agar-gel immunodiffusion was used to distinguish between serotypes a and d. The epidemiological survey suggested that serotype c strains were most prevalent in dental plaques of Japanese children. The d and e serotypes were rare and serotypes a and b were not detected. It was also noted that more than one serotype of S. mutans could be found in the same locus of a carious lesion and that there might be no relationship between the degree of caries and the causative serotype(s) of S. mutans.

Antibodies, Bacterial↗

PubMed2005

Kinetic characterization of P-type membrane ATPase from Streptococcus mutans.

The proton translocating membrane ATPase of oral streptococci has been implicated in cytoplasmatic pH regulation, acidurance and cariogenicity. Studies have confirmed that Streptococcus mutans is the most frequently detected species in dental caries. A P-type ATPase that can act together with F(1)F(o)-ATPase in S. mutans membrane has been recently described. The main objective of this work is to characterize the kinetic of ATP hydrolysis of this P-type ATPase. The optimum pH for ATP hydrolysis is around 6.0. The dependence of P-type ATPase activity on ATP concentration reveals high (K(0.5)=0.27 mM) and low (K(0.5)=3.31 mM) affinity sites for ATP, exhibiting positive cooperativity and a specific activity of about 74 U/mg. Equimolar concentrations of ATP and magnesium ions display a behavior similar to that described for ATP concentration in Mg(2+) saturating condition (high affinity site, K(0.5)=0.10 mM, and low affinity site, K(0.5)=2.12 mM), exhibiting positive cooperativity and a specific activity of about 68 U/mg. Sodium, potassium, ammonium, calcium and magnesium ions stimulate the enzyme, showing a single saturation curve, all exhibiting positive cooperativities, whereas inhibition of ATPase activity is observed for zinc ions and EDTA. The kinetic characteristics reveal that this ATPase belongs to type IIIA, like the ones found in yeast and plants.

Adenosine Triphosphate↗

PubMed2005

Thermal destabilization of non-phosphorylating glyceraldehyde-3-phosphate dehydrogenase from Streptococcus mutans upon phosphate binding in the active site.

Catalysis by the NADP-dependent non-phosphorylating glyceraldehyde-3-phosphate dehydrogenase (GAPN) from Streptococcus mutans, a member of the aldehyde dehydrogenase (ALDH) family, relies on a local conformational reorganization of the active site. This rearrangement is promoted by the binding of NADP and is strongly kinetically favored by the formation of the ternary complex enzyme.NADP.substrate. Adiabatic differential scanning calorimetry was used to investigate the effect of ligands on the irreversible thermal denaturation of GAPN. We showed that phosphate binds to GAPN, resulting in the formation of a GAPN.phosphate binary complex characterized by a strongly decreased thermal stability, with a difference of at least 15 degrees C between the maximum temperatures of the thermal transition peaks. The kinetics of phosphate association and dissociation are slow, allowing both free and GAPN.phosphate complexes to be observed by differential scanning calorimetry and to be separated by native polyacrylamide electrophoresis run in phosphate buffer. Analysis of a set of mutants of GAPN strongly suggests that phosphate is bound to the substrate C-3 subsite. In addition, the substrate analog glycerol-3-phosphate has similar effects as does phosphate on the thermal behavior of GAPN. Based on the current knowledge on the catalytic mechanism of GAPN and other ALDHs, we propose that ligand-induced thermal destabilization is a mechanism that provides to ALDHs the required flexibility for an efficient catalysis.

Binding Sites↗

PubMed1992

Cloning of a locus involved in Streptococcus mutans intracellular polysaccharide accumulation and virulence testing of an intracellular polysaccharide-deficient mutant.

The streptococcal transposon Tn916 (Tcr) was used to isolate mutants of Streptococcus mutans altered in glycogen accumulation to investigate whether glycogenlike intracellular polysaccharides (IPS) play an important role in S. mutans-induced caries formation. S. mutans UA130 (serotype c) was transformed with the Escherichia coli plasmid pAM620 (Tn916), and the resultant transposon libraries were screened for glycogen content by iodine staining. A transposon mutant, designated SMS201, demonstrated a glycogen-deficient phenotype on glucose-enriched medium. Quantitative electron microscopy confirmed that IPS concentrations were significantly reduced in SMS201 relative to the wild-type progenitor strain, UA130. Importantly, reversion to wild type correlated at all times with loss of the transposon. Transposon excisants were used to facilitate cloning of the streptococcal gene(s) involved in glycogen biosynthesis and storage. A 2.1-kb chromosomal determinant (glgR) which encodes a putative regulator of S. mutans glycogen accumulation was isolated. A stable deletion mutation (delta glgR) was subsequently generated in E. coli and introduced into S. mutans by allelic exchange. The resultant glycogen synthesis-deficient mutant, SMS203, demonstrated a significantly reduced cariogenic potential (P less than 0.01) on the buccal, sulcal, and proximal surfaces of teeth in germfree rats, relative to animals challenged with the glycogen synthesis-proficient progenitor strain, UA130. These observations confirm previous reports (J. M. Tanzer, M. L. Freedman, F. N. Woodiel, R. L. Eifert, and L. A. Rinehimer, p. 597-616, in H. M. Stiles, W. J. Loesche, and T. L. O'Brien, ed., Proceedings in Microbiology. Aspects of Dental Caries. Special Supplement to Microbiology Abstracts, vol. 3, 1976) which implicate IPS as significant contributors to the S. mutans cariogenic process.

Animals↗

PubMedDate not supplied

Failure of rabbit anti-Streptococcus mutans serum to penetrate in vitro plaque.

An indirect fluorescent antibody technique indicated that specific antiserums did not penetrate in vitro plaque formed by Streptococcus mutans. Specific reactions did occur between the antiserums and antigens in the surface layers of plaque globules. Measurements of plaque diameters indicated that the serums exerted a nonspecific effect of enhancing plaque growth.

Animals↗

PubMed1976

Effect of glucose and sucrose on the survival in batch culture of Streptococcus mutans C67-1 and a non-cariogenic mutant C67-25. Morphological studies.

This study comprised an ultrastructural examination of a cariogenic strain of Streptococcus mutans, C67-1, and a non-cariogenic mutant of that strain, C67-25. The aim of the work was to define more clearly the relationship between S. mutans and dental caries and, more specifically, to elicit ultrastructural evidence for the conclusion from a previous investigation that the greater survival of the parent strain in sucrose broth at uncontrolled pH was related partly to the production in this medium of abundant extracellular polysaccharide (EPS). The strains were grown as previously in 5% (w/v) glucose or sucrose broths, the pH being either allowed to fall or maintained above 6.0, and processed by the thiosemicarbazide technique for election microscopy. It was confirmed that EPS was most abundant in the sucrose broth culture of the parent strain at uncontrolled pH. While the presence of abundant EPS relates to the greater survival of the parent strain in sucrose broth at uncontrolled pH, this organism possesses at least one other mechanism of survival in acid media, possibly dependent on cell wall properties, in view of its greater cell wall thickness and increased survival in pH-uncontrolled glucose broth in the absence of detectable EPS production. It is postulated that intracellular and extracellular polysaccharide formation, cell wall thickening and reduced viability were indicators of unfavourable growth conditions in the test media. Cariogenic strains of S. mutans appear to be able to survive better under such conditions and hence the prevalence of this and other polysaccharide-producing organisms in stagnant sites in natural dental plaques.

Cell Membrane↗

PubMed2000

Mutational analysis of the C-terminal anchoring domains of Streptococcus mutans P1 antigen: role of the LPXTGX motif in P1 association with the cell wall.

The salivary agglutinin-interacting adhesin P1 of Streptococcus mutans is anchored to the cell wall via the carboxy (C) terminus, which contains a wall-associated domain, a conserved LPXTGX motif, a hydrophobic domain, and a charged tail. To further investigate the role of the C-terminal anchoring regions in cell wall sorting and anchoring, mutational analysis was performed on P1 in this study. Three truncated P1 mutants and seven site-directed mutants were generated by a polymerase chain reaction-based technique. The mutated P1 genes were returned to the P1-negative S. mutans SM3352 for expression and localization studies by ELISA and Western immunoblotting. The results showed that P1 mutants with deletion of the hydrophobic domain and charged tail, or deletion of the charged tail alone resulted in the secretion of P1 to the culture medium. Results from cellular fractionation experiments with the truncated mutants showed that P1 was not trapped in the membrane or cytoplasm. The site-directed mutants showed normal distribution of P1 to the cell surface as compared to the wild-type. However, when cell walls prepared from the site-directed mutants were boiled with SDS, P1 could be removed readily from the mutants with Thr residue in the LPNTGV motif, altered to either Ser (T1531S) or Phe (T1531F); the mutant with Thr and Gly residues altered to two Phe residues (TG1531-1532FF), and the LPNTGV-deleted mutant (LPNTGV-). In contrast, the wild-type P1 and the other three site-directed P1 mutants (P1529V, N1530I, and G1532F) could not be removed by boiling SDS. When the cell wall P1s from the wild-type, mutants P1529V, N1530I, and G1532F were reacted with an antibody directed against the hydrophobic domain and charged tail, no reaction was detected. However, P1s from mutants T1531S, T1531F, TG1531-1532FF, and LPNTGV- were recognized by the antibody, indicating that the inability of these mutated P1s to firmly link to the cell wall was the result of failure in proteolytic cleavage of the hydrophobic domain and charged tail. In summary, the results suggest that the charged tail plays a decisive role in sorting P1 to the cell surface, while the LPXTGX motif determines the nature of P1-cell wall association. The Thr residue of the LPXTGX motif is required for enzymatic processing to link P1 to the cell wall, presumably via a covalent bond.

Adhesins, Bacterial↗

PubMed2004

Inhibitory effect of water-soluble chitosan on growth of Streptococcus mutans.

The present study was undertaken to evaluate the effects of pH and the degree of polymerization of chitosan on the inhibition of growth of Streptococcus mutans. Three types of chitosan, polymer, oligomer and monomer, were used at 4% (W/V) and three different levels of pH: 6.0, 6.5 and 7.4. Bactericidal activity was calculated by the growth ratio. Chitosan oligomer significantly inhibited bacterial growth at a pH value of 6.5. All three types of chitosan strongly inhibited bacterial growth at pH 6.0. Furthermore, nearly complete inhibition was obtained with 2%(W/V) chitosan solution at constant pH 6.5. This study is the first to report that water-soluble chitosan directly suppresses the growth of the typical cariogenic bacterium S. mutans even at pH 6.5, without causing demineralization of the tooth surface.

Adjuvants, Pharmaceutic↗

PubMed1986

Effects of certain salts on glucosyltransferase synthesis by Streptococcus mutans strain PS-14.

We investigated the effects of various salts on the synthesis of extracellular glucosyltransferase in a partially defined medium (M4) by Streptococcus mutans strain PS-14 and by certain other selected strains. The levels of glucosyltransferase produced by S. mutans strain PS-14 were found to increase to a maximum of seven-fold with increasing (NH4)2SO4 concentrations. However, at a 2% concentration of the salt, the level was stimulated 2.5-fold, and the growth was inhibited by 75%. A 1% concentration of MgSO4 or NaCl also caused an increase of glucosyltransferase of six-fold or 2.4-fold, respectively. However, for S. mutans strain B-13N, the enzyme production was not stimulated by (NH4)2SO4, MgSO4, or NaCl. Moreover, the enzyme production by serotypes c, e, and f was found to be stimulated by 1% (NH4)2SO4, whereas the enzyme production by serotypes d and g was not affected.

Ammonium Sulfate↗

PubMed1985

Lysozyme-mediated de-chaining of Streptococcus mutans and its antibacterial significance in an acidic environment.

The ability of physiological amounts of lysozyme to de-chain two serotype c strains of Streptococcus mutans was determined. Both human and hen lysozymes were equally effective in chain breakage of S. mutans DPR and S. mutans DJR. De-chaining did not affect growth of cultures, but resulted in finely dispersed suspensions, at stationary phase, which were visibly different from untreated cultures. Less than 50 micrograms lysozyme per ml culture medium reduced chain length to virtually all diplococci and single cells, and this chain disruption increased total viable cell count. De-chaining required an active enzyme indicating that a degree of hydrolysis of the peptidoglycan occurred at the septae of the streptococci. De-chained S. mutans did not survive as well as streptococci of normal chain length when incubated under acidic conditions (pH 5.5), but gross cellular lysis was not apparent. The reduced aciduric property of the disrupted chains may have been due to a participation of autolysins or to a lethal triggered by the lysozyme-damaged peptidoglycan. De-chaining may be a mechanism by which lysozyme could regulate the levels of S. mutans in acidogenic plaque samples.

Acids↗

PubMed1979

Examination of parotid saliva for antibodies reacting with Streptococcus mutans, lipoteichoic acid and peptidoglycan by the enzyme-linked immunosorbent assay.

Human parotid saliva was investigated for the presence of IgA antibodies reacting with Streptococcus mutans, lipotechoic acid (LTA) and peptidoglycan. By using an enzyme-linked immunosorbent assay, ELISA, it was shown that the salivas of 12 subjects contained antibodies reacting with S. mutans serotype c and d and with LTA. Six salivas were tested against peptidoglycan but these tests indicated only low levels of antibodies. Absorption of saliva with whole cells of S. mutans inhibited the homologous reaction by up to 87% and the reaction with LTA by up to 52%. Also prior treatment of saliva with LTA caused a decrease in the salivary IgA reaction with LTA and with whole cells of S. mutans. Addition of peptidoglycan to saliva did not markedly affect the salivary IgA reaction with S. mutans. The data show that LTA may be responsible for part of the salivary IgA reaction with whole cells of S. mutans. The significance of LTA in this reaction may vary between different subjects and for different serotypes of S. mutans.

Adolescent↗

PubMed1997

Salivary distribution of Streptococcus mutans in schoolchildren from Rome (Italy).

Five-hundred-seventy-seven, 6 year old schoolchildren from Rome were examined. 67.8% of them harboured 1 x 10(5) or more Streptococcus mutans CFU per milliliter of saliva. This value was higher than values reported by other Authors. However, the caries prevalence of the subjects in this study was lower than values shown by some of the other study-populations, suggesting that different S. mutans distributions of different populations are not entirely explained by the differences in caries prevalence and, in order for the comparison to be possible, the other factors affecting mutans distributions should be considered.

Child↗

PubMed2005

[Study on lactate dehydrogenase activity of Streptococcus mutans isolates derived from caries-active and caries-free individuals].

OBJECTIVE: To preliminarily investigate the relationship between the Lactate dehydrogenase (LDH) activity of Streptococcus mutans (S. mutans) and dental caries initiation. METHODS: 100 S. mutans strains derived from caries-active and caries-free individuals were cultured in BHI medium supplemented with glucose. Cells were extracted and ruptured, and the extracted liquid protein was quantified with Coomassie brilliant blue G250 staining methods. LDH activity was assayed using the pyruvate-dependent oxidation of NADH-with and without FDP. RESULTS: LDH activity of the two groups strains had no difference (P > 0.05), but the distribution of differ class enzyme activity strains in the two groups was different (P < 0.05). CONCLUSION: LDH activity of S. mutans is correlated to the initiation of dental caries to some extent. The measurement methods in this study can be applied in preliminary quantitation of LDH activity and the screening of S. mutans strains.

Case-Control Studies↗

PubMed2004

Genotypic diversity and virulence traits of Streptococcus mutans in caries-free and caries-active individuals.

The present study evaluated the relationship between clonal diversity and some virulence traits of Streptococcus mutans isolated from eight caries-free and eight caries-active subjects. A total of 155 S. mutans isolates from caries-free subjects and 144 isolates from caries-active subjects were obtained from samples of saliva, dental plaque and tongue surface and identified by PCR. The isolates were submitted to arbitrarily primed (AP)-PCR (OPA-2 and OPA-13) and multilocus enzyme electrophoresis (MLEE) to establish the genotypic diversity. Production of water-insoluble glucan (WIG) (monitored by SDS-PAGE), final pH of cultures and the ability of bacterial cells to adhere to smooth glass in the presence of sucrose were measured. High and comparable abilities of MLEE and AP-PCR were found to distinguish S. mutans genotypes, using Simpson's index of discrimination (0.971 and 0.968, respectively). The results showed a significant difference (P < 0.01) in the number of genotypes when caries-free and caries-active groups were compared by both fingerprinting methods used. Final pH (P = 0.32) and the percentage of adherence to a glass surface (P = 0.62) did not show differences between the two groups; however, the intensities of WIG bands from the caries-active group were greater than those from the caries-free group (P < 0.01). In addition, WIG was positively correlated with the ability of S. mutans to adhere to a glass surface (r = 0.34, P = 0.02) from caries-active subjects. These data showed that AP-PCR analysis and MLEE are both effective methods for assessing the genetic relatedness of S. mutans. Using these techniques, it was found that there is a larger number of genotypes of S. mutans with increased ability to synthesize WIG in caries-active individuals.

Adolescent↗