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PubMed2002

PCR detection of Streptococcus mutans and S. sobrinus in dental plaque samples from Japanese pre-school children.

Streptococcus mutans and S. sobrinus are associated with the development of dental caries. These bacteria were detected by PCR and then their presence was compared with the incidence of dental caries in 77 Japanese pre-school children. Plaque samples were collected from all erupted tooth sites in the subjects, aged 3-5 years old and each with primary dentition, with a sterile toothbrush. A dental examination was performed for dmft (decayed, missing, filled, total) with the WHO caries diagnostic criteria. In all subjects, the prevalence of S. mutans and S. sobrinus was 72.8% and 61.1%, respectively; 19 (24.7%) were positive for S. mutans alone, 10 (13.0%) were positive for S. sobrinus alone, 37 (48.1%) were positive for both S. mutans and S. sobrinus, and 11 (14.3%) were negative for both S. mutans and S. sobrinus. The dmft scores of children positive for both S. mutans and S. sobrinus were significantly higher than those positive for S. mutans alone. These results indicate that children harbouring both S. mutans and S. sobrinus have a significantly higher incidence of dental caries than those with S. mutans alone.

Age Distribution↗

PubMed1990

Metabolism of progesterone and testosterone by Bacillus cereus strain Socransky 67 and Streptococcus mutans strain Ingbritt.

Bacillus cereus strain Socransky 67 and Streptococcus mutans strain Ingbritt were grown overnight in complex medium and then in fresh medium flasks for 5 h. The bacterial cells in the medium were centrifuged and resuspended; 4-14C-progesterone or 4-14C-testosterone was added, and the samples were incubated for 2 h at 37 degrees C in a shaking water bath. The metabolites were analyzed with column and thin layer chromatography and radioautography and quantified by liquid scintillation counting. On the basis of the metabolites found it was concluded that B. cereus strain Socransky 67 contains 5 alpha-steroid hydrogenase, and 3 beta-, 17 beta- and 20 alpha-hydroxysteroid dehydrogenases and probably also steroid hydroxylases, and that S. mutans strain Ingbritt contains 5 alpha- and 5 beta-steroid hydrogenases, and 3 alpha-, 17 beta- and 20 alpha-hydroxysteroid dehydrogenases. The metabolic activity of B. cereus is several times higher than that of S. mutans. We suggest that the greater ability of B. cereus to metabolize progesterone and testosterone is probably due to its growth milieu in the gingival sulcus, where it is nearer to the gingival tissue.

Bacillus cereus↗

PubMed2003

Insertional inactivation of pac and rmlB genes reduces the release of tumor necrosis factor alpha, interleukin-6, and interleukin-8 induced by Streptococcus mutans in monocytic, dental pulp, and periodontal ligament cells.

Streptococcus mutans possesses different cell wall molecules, such as protein of the I/II family, the serotype f polysaccharide rhamnose glucose polymer (RGP), and lipoteichoic acid (LTA), which act as adhesins and modulins, allowing S. mutans to colonize teeth and cause dental caries and pulpitis. We tested several isogenic mutants of S. mutans defective in protein I/II and/or RGP, as well as purified modulins such as protein I/II, RGP, and LTA, for their binding and activation abilities on monocytic, dental pulp (DP), and periodontal ligament (PDL) cells. Our results demonstrate that both protein I/II and RGP play important roles in streptococcal adherence to human monocytic and fibroblastic cells, whereas LTA is only a minor adhesin. In the activation process, the cytokine response elicited is polarized toward a Th1 response which seems principally due to protein I/II and RGP. Even if protein I/II seems to be more efficient in its purified form in triggering cells to release interleukin-8 (IL-8), RGP is the most efficient cytokine-stimulating component in intact bacteria, while LTA plays only a minor role. In cell activation, we showed, by using either cytochalasin D or coated ligands, that internalization of either S. mutans, S. mutans isogenic mutants, or purified ligands is not necessary to trigger cells to release IL-8. We also showed that, besides the implication of monocytes in pulpal inflammation, fibroblast-like cells such as DP and PDL cells are also actively implicated in local inflammation and in the generation of a Th1 response after stimulation with S. mutans cells or antigens.

Adhesins, Bacterial↗

PubMed1989

Isolation and characterization of the Streptococcus mutans gtfD gene, coding for primer-dependent soluble glucan synthesis.

Two glucosyltransferase genes from Streptococcus mutans GS-5, gtfB and gtfC, have been previously isolated and sequenced in this laboratory. In the present communication a third gtf gene, gtfD, was isolated and characterized. Isolation of the gene involved a novel procedure utilizing the integration plasmid pVA891. A peptide expressed by the 1.7-kilobase DNA fragment from strain NHS1 (containing deletions in both the gtfB and gtfC genes) was initially identified in a pUC18 clone bank with antiglucosyltransferase antibodies. This fragment was integrated into the GS-5 chromosome following ligation into pVA891 and transformation, yielding strain DP2. The vector together with one complete and one incomplete copy of the gtfD gene was removed from the chromosome of strain DP2 following EcoRI digestion, religation, and transformation of E. coli HB101. The resultant plasmid, pNH4, expressed glucosyltransferase S (GTF-S) activity. The enzyme was purified to near homogeneity and was shown to synthesize water-soluble glucan exclusively in a primer-dependent manner. The molecular mass (155 kilodaltons) and the kinetic parameters of the purified enzyme were similar to those observed for the GTF-S enzyme previously purified from culture fluids of strain GS-5. Insertional inactivation of the gtfD gene indicated that this gene is not required for in vitro sucrose-dependent adherence to smooth surfaces. Furthermore, inactivation of the gtfD gene in a gtfC gtfB mutant indicated that three distinct gtf genes involved in glucan formation are present on the S. mutans GS-5 chromosome. Southern blot analysis further suggested that the gtfD gene does not share demonstrable homology with the gtf genes from Streptococcus sanguis or Streptococcus sobrinus.

Cloning, Molecular↗

PubMed1999

Interactions of Streptococcus mutans fimbria-associated surface proteins with salivary components.

Streptococcus mutans has been implicated as the major causative agent of human dental caries. S. mutans binds to saliva-coated tooth surfaces, and previous studies suggested that fimbriae may play a role in the initial bacterial adherence to salivary components. The objectives of this study were to establish the ability of an S. mutans fimbria preparation to bind to saliva-coated surfaces and determine the specific salivary components that facilitate binding with fimbriae. Enzyme-linked immunosorbent assay (ELISA) established that the S. mutans fimbria preparation bound to components of whole saliva. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot techniques were used to separate components of whole saliva and determine fimbria binding. SDS-PAGE separated 15 major protein bands from saliva samples, and Western blot analysis indicated significant binding of the S. mutans fimbria preparation to a 52-kDa salivary protein. The major fimbria-binding salivary protein was isolated by preparative electrophoresis. The ability of the S. mutans fimbria preparation to bind to the purified salivary protein was confirmed by Western blot analysis and ELISA. Incubation of the purified salivary protein with the S. mutans fimbria preparation significantly neutralized binding of the salivary protein-fimbria complex to saliva-coated surfaces. The salivary protein, whole saliva, and commercial amylase reacted similarly with antiamylase antibody in immunoblots. A purified 65-kDa fimbrial protein was demonstrated to bind to both saliva and amylase. These data indicated that the S. mutans fimbria preparation and a purified fimbrial protein bound to whole-saliva-coated surfaces and that amylase is the major salivary component involved in the binding.

Amylases↗

PubMed1979

Longitudinal survey of the distribution of various serotypes of Streptococcus mutans in infants.

The establishment of various serotypes of Streptococcus mutans was studied serologically in plaque samples collected from label surfaces of upper primary incisors of 22 infants (starting age, 5 to 13 months) over a period fo 30 months. Clinical examinations were also performed. No clear-cut association between the initiation of dental caries and previous detection of S. mutans was noted. However, all 12 of the infants with caries had S. mutans isolated at some time during the course of this study. The most common serotype isolated at the initial establishment of S. mutans on the tooth surfaces was serotype c, whereas types d, e, and g became established in a few cases. During the test period, changes in the distribution of serotypes of S. mutans were observed in some cases. The initiation of carious lesions could be found in a few cases even when S. mutans comprised about 1% or less of the total streptococcal count of the specimen from the tooth surfaces. Serotype d/g strains tended to develop carious lesions on smooth surfaces, although serotype c was isolated from almost all individuals who developed caries.

Child, Preschool↗

PubMed1990

Epidemiological application of a new bacteriocin typing scheme for Streptococcus mutans.

We propose a new bacteriocin typing scheme for Streptococcus mutans (Biotype I) using nine producer strains and a numerical code with three figures. Its application in 75 unrelated S. mutans strains allowed us to type all microorganisms and to obtain a total of 15 bacteriocin types. Its epidemiological use in two family groups allowed us to obtain two bacteriocin types in each one and to show the type relations between the different family components.

Adolescent↗

PubMed1983

Expression of a Streptococcus mutans glucosyltransferase gene in Escherichia coli.

Chromosomal DNA from Streptococcus mutans strain UAB90 (serotype c) was cloned into Escherichia coli K-12. The clone bank was screened for any sucrose-hydrolyzing activity by selection for growth on raffinose in the presence of isopropyl-beta-D-thiogalactoside. A clone expressing an S. mutans glucosyltransferase was identified. The S. mutans DNA encoding this enzyme is a 1.73-kilobase fragment cloned into the HindIII site of plasmid pBR322. We designated the gene gtfA. The plasmid-encoded gtfA enzyme, a 55,000-molecular-weight protein, is synthesized at 40% the level of pBR322-encoded beta-lactamase in E. coli minicells. Using sucrose as substrate, the gtfA enzyme catalyzes the formation of fructose and a glucan with an apparent molecular weight of 1,500. We detected the gtfA protein in S. mutans cells with antibody raised against the cloned gtfA enzyme. Immunologically identical gtfA protein appears to be present in S. mutans cells of serotypes c, e, and f, and a cross-reacting protein was made by serotype b cells. Proteins from serotype a, g, and d S. mutans cells did not react with antibody to gtfA enzyme. The gtfA activity was present in the periplasmic space of E. coli clones, since 15% of the total gtfA activity was released by cold osmotic shock and the clones were able to grow on sucrose as sole carbon source.

Biological Transport↗

PubMed2005

Smx nuclease is the major, low-pH-inducible apurinic/apyrimidinic endonuclease in Streptococcus mutans.

The causative agent of dental caries in humans, Streptococcus mutans, outcompetes other bacterial species in the oral cavity and causes disease by surviving acidic conditions in dental plaque. We have previously reported that the low-pH survival strategy of S. mutans includes the ability to induce a DNA repair system that appears to involve an enzyme with exonuclease functions (K. Hahn, R. C. Faustoferri, and R. G. Quivey, Jr., Mol. Microbiol 31:1489-1498, 1999). Here, we report overexpression of the S. mutans apurinic/apyrimidinic (AP) endonuclease, Smx, in Escherichia coli; initial characterization of its enzymatic activity; and analysis of an smx mutant strain of S. mutans. Insertional inactivation of the smx gene eliminates the low-pH-inducible exonuclease activity previously reported. In addition, loss of Smx activity renders the mutant strain sensitive to hydrogen peroxide treatment but relatively unaffected by acid-mediated damage or near-UV irradiation. The smx strain of S. mutans was highly sensitive to the combination of iron and hydrogen peroxide, indicating the likely production of hydroxyl radical by Fenton chemistry with concomitant formation of AP sites that are normally processed by the wild-type allele. Smx activity was sufficiently expressed in E. coli to protect an xth mutant strain from the effects of hydrogen peroxide treatment. The data indicate that S. mutans expresses an inducible, class II-like AP endonuclease, encoded by the smx gene, that exhibits exonucleolytic activity and is regulated as part of the acid-adaptive response of the organism. Smx is likely the primary, if not the sole, AP endonuclease induced during growth at low pH values.

Bacterial Proteins↗

PubMed1999

Induction of an AP endonuclease activity in Streptococcus mutans during growth at low pH.

The oral microbe Streptococcus mutans uses adaptive mechanisms to withstand the fluctuating pH levels in its natural environment. The regulation of protein synthesis is part of the mechanism of acid adaptation and tolerance in S. mutans. Here, we demonstrate that the organism's acid-inducible protein repertoire includes an AP endonuclease activity. This abasic site-specific endonuclease activity is present at greater levels in cells grown at low pH than in cells grown at pH 7, and is apparently independent of the RecA protein. Experiments using tetrahydrofuran or alpha-deoxyadenosine-containing substrates indicate that the activity induced at low pH may be similar to the activity of exonuclease III from E. coli. Acid-adapted S. mutans also shows an increased survival rate after exposure to near-UV radiation in both the wild type and a recA strain. Far-UV radiation resistance is observed in the wild type only. The endonuclease activity was purified approximately 500-fold from an S. mutans recA mutant strain grown at pH 5. Initial characterization revealed a 3' to 5' exonuclease activity, and showed additional functional similarities to DNA repair enzymes from other organisms.

Calcium Chloride↗

PubMed1981

Effect of aqueous solutions of sorbitol-xylitol on plaque metabolism and on growth of Streptococcus mutans.

The present study showed that the growth of Streptococcus mutans strain GS5 was inhibited by xylitol, and this indicates together with previous reports that this is a common phenomenon in this species. Sorbitol was found to increase the growth of S. mutans strains OMZ 176 and GS5 slightly compared with cultures with no external carbon source. Addition of small amounts of xylitol to the sorbitol cultures gave a growth below that of cultures with no extra carbon. Dental plaque challenged with sorbitol gave a small pH drop whereas xylitol caused a negligible decrease in pH. Sorbitol-xylitol challenges gave less acid production than sorbitol challenges alone.

Adult↗

PubMed2004

The F-ATPase operon promoter of Streptococcus mutans is transcriptionally regulated in response to external pH.

Streptococcus mutans F-ATPase, the major component of the acid-adaptive response of the organism, is transcriptionally upregulated at low pH. Fusions of the F-ATPase promoter to chloramphenicol acetyltransferase indicated that pH-dependent expression is still observed with a short promoter that contains a domain conserved between streptococcal ATPase operons.

Bacterial Proton-Translocating ATPases↗

PubMed1984

Isolation of a Streptococcus mutans strain producing a novel bacteriocin.

A strain of Streptococcus mutans has been isolated that produces a bacteriocin with novel properties. Its antibiotic spectrum includes 123 of 124 strains of S. mutans tested and a variety of other gram-positive microorganisms. Experiments with dialysis membranes indicate that the molecular weight of the bacteriocin is less than 1,000. Mutants of the producer strain were obtained that are deficient in bacteriocin production or produce twofold elevated amounts. The ability of these strains to superinfect or preemptively colonize the oral cavities of rats correlated with the amount of bacteriocin they produced.

Animals↗

PubMed1990

[Isolation and biotyping of Streptococcus mutans among preschool children in Kaohsiung city].

Strains of streptococcus mutans were isolated from the saliva of preschool children in Kaohsiung City. The unstimulated whole saliva samples were inoculated onto modified Gold's agar plates and incubated for 24-48 hours anaerobically at 37 degrees C. Strains of S. mutans were classified according to Shklair and Keene's biochemical methods and biotyped according to the methods of Farghaly et al. S. mutans could be detected in 102 (89.5%) of 114 preschool children. The most common biotype of S. mutans in single isolation was biotype I (72.9%). The percentages of the other biotypes are as follows: biotype II (5.2%), biotype III (7.3%), biotype IV (7.3%) and biotype V (7.3%). Our study revealed that the deft index was significantly higher in children who were biotype I carriers than in those who were nonbiotype I carriers. This observation suggests that biotype I may be related to the higher incidence of dental caries in our preschool children.

Bacterial Typing Techniques↗

PubMed1982

Pyridine analogs inhibit the glucosyltransferase of Streptococcus mutans.

Soluble glucan synthesis catalyzed by dextransucrase preparations from Streptococcus mutans 6715 were inhibited by pyridoxal-5-phosphate and several other pyridine analogs, including pyridoxine, pyridoxamine, pyridoxamine-5-phosphate, pyridoxal, and 4-pyridoxic acid. Pyridine and pyridine-4-carboxaldehyde were not effective inhibitors of the enzyme. Kinetic analyses suggested that pyridoxal-5-phosphate is a noncompetitive inhibitor of dextransucrase. The inactivation was dependent on time, pyridoxal-5-phosphate concentration, and hydrogen ion concentration. Apparent Ki values were 4.9 mM at pH 7.0 and 4.2 mM at pH 5.5. Dextransucrase activity could be restored by dialysis to remove the inhibitors. Maximum inhibition was observed after a 120-min incubation of the enzyme with pyridoxal-5-phosphate. The pH optima for inhibition by pyridoxal-5-phosphate were 4 and 7. The sucrose-dependent adherence of S. mutans cells to saliva-coated hydroxylapatite beads was also inhibited by pyridoxal-5-phosphate but only marginally by the other pyridine anatogs. In addition, pyridoxal-5-phosphate markedly reduced the rate of acid production by intact S. mutans cells from sucrose or glucose substrates. Another pyridoxal-5-phosphate analog, 2-methyl-5-hydroxypyridine, was also effective in preventing the production of acid by S. mutans from sucrose or glucose. When S. mutans cells were preincubated with pyridoxal-5-phosphate or pyridine analogs, significant reductions in the rate of D-glucose uptake were observed. It is suggested that the inhibition of dextransucrase occurs because of a change iun enzyme conformation which results from the binding of the pyridine derivatives. The results suggest that pyridoxal-5-phosphate or structural analogs may ultimately be useful in reducing the incidence of dental caries.

Adhesiveness↗

PubMed1985

Anti-dental caries effect in rats and man of a bacteriocin purified from the oral bacterium Streptococcus mutans C3603.

Specific pathogen-free rats infected with Streptococcus mutans PS-14 (serotype c) and fed a cariogenic diet containing 380 parts/10(6) of bacteriocin, purified from Strep. mutans C3603, developed significantly fewer carious lesions than controls infected with Strep. mutans and fed the same diet without bacteriocin. The caries-inhibitory effect was 58.7 per cent. Oral appliances fixed with bovine enamel slabs were worn by volunteers to test bacteriocin C3603. The enamel slabs were treated with 500 parts/10(6) bacteriocin in 3 per cent sucrose solution for 10 min, 4 times daily, or with 3 per cent sucrose solution, 3 times daily, for 10 min and just before bedtime with 500 parts/10(6) bacteriocin once for 1 min. The bacteriocin exerted a strong inhibition of cariogenicity of sucrose.

Animals↗

PubMed1995

Primer extension analysis of Streptococcus mutans promoter structures.

To characterize the promoter structures of Streptococcus mutans genes, primer extension analysis was carried out with 4 genes previously isolated in this laboratory. An analysis of the transcription start sites for the gtfB, gtfC, gtfD and ftf genes revealed that each transcript was initiated at a purine residue. Based on these sites, the -10 and -35 sequences for each transcript were deduced and compared. For all 4 transcripts, the -10, but not the -35, sequences were homologous to the Escherichia coli promoter consensus sequences.

Base Sequence↗

PubMed1987

Sequence analysis of the gtfB gene from Streptococcus mutans.

The nucleotide sequence of the gtfB gene from Streptococcus mutans GS-5, coding for glucosyltransferase I activity, was determined. The gene codes for a strongly hydrophilic protein with a molecular size of 165,800 daltons. The deduced amino acid sequence revealed a typical gram-positive bacterial signal sequence at the NH2 terminus of the protein and 3.5 direct repeating units (each containing 65 amino acids) at the COOH terminus. Nucleotide sequencing of the region immediately downstream from the gtfB gene revealed the presence of a putative gene coding for an extracellular protein. This open reading frame is partially homologous to the gtfB gene.

Amino Acid Sequence↗