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PubMed1996

Isolation and preliminary characterization of the Streptococcus mutans rpsJ gene.

We previously reported that four putative open reading frames were identified in the regions flanking the Streptococcus mutans GS-5 fructosyltransferase gene. For one of these, ORF 4, only a small region had been isolated and the first 30 nucleotides had been sequenced. In order to determine whether this open reading frame is part of an expressed gene, we isolated a DNA fragment containing intact ORF 4 and a portion of the downstream ORF 5 by inverse polymerase chain reaction. A comparison of the deduced amino acid sequences of ORF 4 and ORF 5 with other proteins revealed that the ORF 4 and ORF 5 gene products were highly homologous to ribosomal proteins S10 and L3, respectively, of several bacteria. To identify the precise transcriptional start site for the ORF 4 gene, primer extension analysis was carried out. The results indicated initiation at a G residue with corresponding -10 and -35 regions homologous to the Escherichia coli consensus promoter sequences. These results indicate that the sequences of ORF 4 and ORF 5 are consistent with the structures of ribosomal proteins S10 and L3, respectively, and are present in a ribosomal protein operon.

Bacterial Proteins↗

PubMed1977

Fluoride uptake by Streptococcus mutans 6715.

The short-term kinetics of fluoride uptake by cells from 20- to 22-h cultures of Streptococcus mutans strain 6715 were studied using rapid filtration and centrifugation techniques. Saline-suspended organisms were diluted with fluoride-containing solutions buffered at four different pH values (2.0, 4.0, 5.5, and 8.2). Fluoride disappearance from the medium was inversely related to pH and to the duration of the exposure at any given pH. The uptake was rapid and extensive at the lower pH values and decreased as the pH increased. Media fluoride concentrations subsequently increased; i.e., fluoride was released from the cells. The presence of glucose, cyanide, or iodoacetate did not influence the results. However, preincubation of the cells in fluoride-free buffers, followed by the addition of fluoride, reduced fluoride uptake markedly. Cell-to-media pH gradients were determined by the distribution of 14C-labeled 5,5-dimethyl-2,4-oxazolidinedione. Fluoride uptake was found to be a function of the magnitude of the pH gradient (P less than 0.001). It is hypothesized that fluoride uptake occurs by the diffusion of hydrogen fluoride and the subsequent trapping of ionic fluoride.

Biological Transport↗

PubMed2001

[Effects of para-aminobenzoic acid (PABA) on growth of Streptococcus mutans].

OBJECTIVE: The aim of this study is to examine effects of para-aminobenzoic acid (PABA) on the growth of Streptococcus mutans (S. mutans). METHODS: Different concentrations of PABA (10(-10)-10(-3) g/L) were separately transferred to modified Carlsson medium. S. mutans (ATCC 25175) grew in modified Carlsson medium with different concentrations of PABA. All cultures were incubated at 37 degrees C anaerobically in an atmosphere of 80% of nitrogen (v/v), 10% of hydrogen (v/v) and 10% of carbon dioxide (v/v) for 48 hours. The absorbance values of S. mutans were measured by using a spectrometer (UV-1601). The colony forming units (CFU) were obtained by growing S. mutans in media with different concentrations of PABA (10(-10)-10(-3) g/L). RESULTS: Different concentrations of PABA had different stimulating effects on the growth of S. mutans (P < 0.05). But this kind of stimulating effects declined when the concentration of PABA was 10(-3) g/L. CONCLUSION: This experiment indicates PABA has stimulating effects on the growth of S. mutans, and PABA can promote growth of S. mutans.

4-Aminobenzoic Acid↗

PubMed1990

Immunodominant antigens of Streptococcus mutans in dental caries-resistant subjects.

Previously, we reported that dental caries-resistant subjects, who have significantly fewer Streptococcus mutans in whole saliva than caries-susceptible patients, have significantly higher levels of naturally occurring binding and neutralizing parotid salivary immunoglobulin A and serum immunoglobulin G antibodies to native S. mutans antigens than caries-susceptible patients. Recent animal studies indicated that the immunogenicity of swallowed S. mutans may be altered by either saliva-coating or stomach acid-denaturation. These results suggest a difference not only in the quantity of antibody to S. mutans, but also in the antigenic epitopes that caries-resistant subjects synthesize antibody to as compared with caries-susceptible patients. In the present report, sodium dodecyl sulfate-polyacrylamide gel electrophoresis/immunoblotting studies indicate that caries-resistant subjects produce salivary immunoglobulin A and serum immunoglobulin G antibodies to several different (molecular weight: 94, 80, 40, and 35 kilodaltons) as well as several similar (molecular weight: 67, 55, and 30 kilodaltons) S. mutans epitopes as compared to caries-susceptible patients. This provides additional confirmation for our previous binding and functional antibody studies, indicating that caries-resistant subjects synthesize antibodies of different specificities than caries-susceptible patients. This study supports the concept of immune regulation of dental caries by naturally occurring antibodies induced by swallowing S. mutans antigens in saliva.

Antibodies, Bacterial↗

PubMed1996

Characterization of IS199 from Streptococcus mutans V403.

The complete nucleotide sequence of the insertion sequence IS199 has been determined. This novel element was found in Streptococcus mutans V403 where DNA hybridization studies suggested that it was present in multiple copies on the genome. IS199 is 1220 bp and appears unique to the mutans streptococci. A limited epidemiological survey revealed this element to occur infrequently in this group (4/50 strains examined). IS199 belongs to the IS3 family of procaryotic insertion sequence elements. It contained tandem open reading frames (ORFs) reminiscent of the structure of the IS3 class. Additionally, the larger of the two ORF products (ORFB) exhibited amino acid sequence similarities to comparable proteins from IS3 and other elements of this family. Transposition of IS199 gave rise to a 3-bp target site duplication. We were able to insert an antibiotic resistance gene into IS199 enabling us to follow the transposition of this element in S. mutans V403.

Amino Acid Sequence↗

PubMed1990

Evidence that a low-affinity sucrose phosphotransferase activity in Streptococcus mutans GS-5 is a high-affinity trehalose uptake system.

High-affinity sucrose uptake in the oral pathogen Streptococcus mutans is mediated by the phosphoenolpyruvate-dependent phosphotransferase system. In this report, we provide evidence that a lower-affinity sucrose phosphotransferase system in S. mutans GS-5, previously described by others, is in fact a high-affinity trehalose uptake system that also recognizes sucrose as a substrate.

Biological Transport, Active↗

PubMed1974

Morphological study of Streptococcus mutans and two extracellular polysaccharide mutants.

Two extracellular polysaccharide mutants of Streptococcus mutans GS-5 were obtained and examined. The mutants were distinguished by colonial morphology and by growth on and adherence to hard surfaces. A technique was devised which allowed these bacteria to be studied as they appeared when grown on a hard surface in liquid medium which contained sucrose. Negative stains, replicas, and scanning electron micrography clearly revealed differences in cellular aggregation due to the various extracellular polysaccharides produced. Comparison of sections of the adherent parent strain (GS-5) with those of the nonadherent mutant (GS-511) allowed the extracellular polysaccharide(s) responsible for adhesion to be visually localized.

Culture Media↗

PubMed1985

Transmission of Streptococcus mutans in some selected families.

The aim of the present study was to determine the source and transmission route of Streptococcus mutans. The frequency of this organism in saliva and plaque samples was compared among fifteen pairs of mothers and their children. The results showed that most of the mothers harboured almost equal or greater levels of S. mutans than their children. Similarities of the distribution of various serotypes and mutacin types were observed between these mothers and their offspring. Samples were also collected from plaque and/or carious lesions of the relatives of the subjects who carried one of the serotypes other than serotype c as the dominant S. mutans. The strains of the same serotypes of S. mutans which possessed similar mutacin patterns were predominantly detected in the siblings and mothers of each subject. However, a similar distribution of S. mutans strains was not clearly observed in other relatives including fathers, aunts, uncles and grandparents.

Adult↗

PubMed1989

Salivary Streptococcus mutans and caries prevalence in Brazilian schoolchildren.

The aim of the present study was to determine the levels of salivary Streptococcus mutans in Brazilian schoolchildren, and its possible correlation with caries prevalence. A positive correlation between different levels of S. mutans and caries prevalence was observed, individuals with high levels of S. mutans (greater than 100 colonies) had a DMFS significantly higher than those with low or no detectable S. mutans (0, 1-20, 21-40 colonies).

Adolescent↗

PubMed2006

A eukaryotic-type serine/threonine protein kinase is required for biofilm formation, genetic competence, and acid resistance in Streptococcus mutans.

We report an operon encoding a eukaryotic-type serine/threonine protein kinase (STPK) and its cognate phosphatase (STPP) in Streptococcus mutans. Mutation of the gene encoding the STPK produced defects in biofilm formation, genetic competence, and acid resistance, determinants important in caries pathogenesis.

Acids↗

PubMed2000

Xylitol disturbs protein synthesis, including the expression of HSP-70 and HSP-60, in Streptococcus mutans.

Xylitol, a natural sugar alcohol and a caries-preventive carbohydrate sweetener, inhibits xylitol-sensitive wild-type Streptococcus mutans but also selects for its natural xylitol-resistant mutants. The aim of the work was to verify the influence of xylitol on heat shock proteins HSP-60 (GroEL-like) and HSP-70 (DnaK-like) in xylitol-sensitive and xylitol-resistant strains. Cells from fresh isolate S. mutans 123.1 were grown at 37 degrees C and constant pH 7.0. The cell culture was stressed by raising the temperature to 43 degrees C or adding xylitol (4% final). Cell proteins labeled with a cocktail of 14C-amino acids were analyzed by SDS-PAGE and autoradiography whereas HSP-60 and HSP-70 were visualized using Western immunoblotting. In both xylitol-sensitive and xylitol-resistant strains, heat stress was associated with an increase of both HSP-60 (63 kDa) and HSP-70 (71 kDa) and a decrease in the intensity of a number of other protein bands compared with cells maintained at 37 degrees C. Exposure to xylitol but not to other polyols induced a decrease of both these heat shock proteins in the xylitol-sensitive strain but did not modify them in the xylitol-resistant mutant. It also decreased all protein bands above 60 kDa together with a 53 kDa protein and increased the amount of 57-, 50- and 40-kDa proteins in the xylitol-sensitive strain whereas the proteins of the xylitol-resistant strain remained unchanged. The results suggest that xylitol is a strong metabolic inhibitor that disturbs protein synthesis and reduces the expression of HSP-70 and HSP-60 proteins in the wild-type xylitol-sensitive S. mutans but not in the xylitol-resistant natural mutant strain.

Autoradiography↗

PubMed1994

Affinity and specificity of the interactions between Streptococcus mutans antigen I/II and salivary components.

Adherence to salivary pellicle-coated tooth surfaces and aggregation by salivary components of Streptococcus mutans involves a major cell surface protein termed antigen (Ag) I/II. The objectives of this study were to evaluate the affinity and specificity of the interactions between AgI/II and human saliva in assays of 125I-AgI/II binding to saliva-coated hydroxyapatite (SHA) and of S. mutans aggregation by salivary agglutinin (SAG), monitored turbidimetrically. 125I-AgI/II binding to SHA followed saturation kinetics, and Scatchard plot analysis indicated two binding sites with dissociation constants of the order of 10(-10) mol/L and 10(-9) mol/L. The binding to SHA of the C-terminal one-third of AgI/II which corresponds to AgII was less than one-fifth that of the whole molecule and did not show evidence of saturation. The binding of 125I-AgI/II was inhibited by native or recombinant fragments that mapped in the N-terminal part of the molecule and that contained the alanine-rich repeat region, whereas fragments mapping at the central or C-terminal one-third had no effect. As with binding to SHA, the regions of AgI/II which inhibited aggregation mapped at the N-terminal part of the molecule, but, in addition, a recombinant segment mapping at the central part and containing the proline-rich repeat region was also inhibitory. The S. mutans-aggregating activity of SAG or whole saliva was inhibited by amino compounds, and most strongly by L-lysine and analogues possessing omega-primary amine groups. These data support the role of AgI/II as an adhesin with high-affinity binding for SHA receptors, mediated by the N-terminal part of the molecule. This region is also involved in SAG-induced S. mutans aggregation, which is sensitive to amino compounds.

Adhesins, Bacterial↗

PubMed1983

Lysis of Streptococcus mutans BHT by salivary lysozyme.

The aim of this work was to study the bacteriolytic ability of human salivary lysozyme (HSL) on Streptococcus mutans BHT. The cells were grown in a synthetic medium containing 3H-thymidine to monitor DNA release after incubation with either HSL, purified by ion exchange chromatography, or hen egg white lysozyme (HEWL). The experiments demonstrated that HSL as well as HEWL could liberate DNA from cells. The lysis was dependent on enzyme concentration as well as incubation-time. Approximately 80% of the 3H-thymidine was released at final concentrations of 4.5 micrograms/ml and incubation-times exceeding 16 hr. Additional treatment of the suspensions with DNase increased the levels of released radioisotopes. The lytic ability of HSL and HEWL was similar at low concentrations. HSL inactivated with goat antiserum to human lysozyme decreased the liberation of DNA by about 70%. This study suggests that HSL can lyse S. mutans BHT without presence of inorganic ions.

Bacteriolysis↗

PubMed2001

Passive immunization with milk produced from an immunized cow prevents oral recolonization by Streptococcus mutans.

Cell surface protein antigen (PAc) and water-insoluble glucan-synthesizing enzyme (GTF-I) produced by cariogenic Streptococcus mutans are two major factors implicated in the colonization of the human oral cavity by this bacterium. We examined the effect of bovine milk, produced after immunization with a fusion protein of functional domains of these proteins, on the recolonization of S. mutans. To prepare immune milk, a pregnant Holstein cow was immunized with the fusion protein PAcA-GB, a fusion of the saliva-binding alanine-rich region (PAcA) of PAc and the glucan-binding (GB) domain of GTF-I. After eight adult subjects received cetylpyridinium chloride (CPC) treatment, one subgroup (n = 4) rinsed their mouths with immune milk and a control group (n = 4) rinsed with nonimmune milk. S. mutans levels in saliva and dental plaque decreased after CPC treatment in both groups. Mouth rinsing with immune milk significantly inhibited recolonization of S. mutans in saliva and plaque. On the other hand, the numbers of S. mutans cells in saliva and plaque in the control group increased immediately after the CPC treatment and surpassed the baseline level 42 and 28 days, respectively, after the CPC treatment. The ratios of S. mutans to total streptococci in saliva and plaque in the group that received immune milk were lower than those in the control group. These results suggest that milk produced from immunized cow may be useful for controlling S. mutans in the human oral cavity.

Adult↗

PubMed1982

Effect of a fluoride-containing varnish on Streptococcus mutans in plaque and saliva.

The effect of topical application of a fluoride-containing varnish, Duraphat, on the level of Streptococcus mutans in saliva and in dental plaque was investigated in schoolchildren. Samples of saliva and pooled buccal plaque were taken before varnish application and 4, 10 and 21 d after treatment. Fluoride varnish treatment with or without a preceding dental prophylaxis had no significant effect on the plaque and salivary levels of S. mutans. The findings suggest that the caries-reducing effect of fluoride varnish cannot be explained by an alteration of the incidence of S. mutans in dental plaque or in saliva.

Adolescent↗

PubMed1982

Growth rates of Actinomyces viscosus and Streptococcus mutans during early colonization of tooth surfaces in gnotobiotic rats.

Germfree Osborne-Mendel rats were monoassociated with Actinomyces viscosus or Streptococcus mutans. The adherence and subsequent growth of these organisms on the tooth surface was studied by means of total viable cell counts. Both A. viscosus and S. mutans showed a lag phase and an exponential growth phase, similar to logarithmic growth in batch cultures. The exponential growth rates of S. mutans and A. viscosus were 0.63 h-1 (doubling time [td] = 1.1 h) and 0.24 h-1 (td = 2.9 h), respectively. After a period of rapid growth, the rate declined and the populations approached a steady state. The presence of a sucrose-containing diet did not significantly influence the exponential growth rates of A. viscosus and S. mutans, but had a slight negative effect on the initial adherence of S. mutans at the tooth surface.

Actinomyces↗

PubMed1984

Multiple types of the bacterium Streptococcus mutans in the human mouth and their intra-family transmission.

To identify the source of infection with the potentially cariogenic Streptococcus mutans, unstimulated saliva and two approximal plaque samples were examined from each member of 10 families, five of which were re-sampled 6 months later. Each morphological type of Strep. mutans appearing on SB-20 medium was identified by a biochemical micromethod and by bacteriocin typing. Ninety-three per cent of the 46 subjects harboured Strep. mutans and multiple types were detected in 78 per cent of adults and 46 per cent of infected children. Each mouth yielded c/e/f biotypes and 46 per cent also carried d/g types. Generally, saliva types were the same as those in plaque and the second sampling confirmed the first. Most fathers did not share strains with others in the family but all the infected children shared at least one common strain with the mother. The mother as the major source of Strep. mutans infection in young children was confirmed.

Adult↗

PubMed1990

Size of the Streptococcus mutans GS-5 chromosome as determined by pulsed-field gel electrophoresis.

Rare cutting restriction endonucleases were used to cut the Streptococcus mutans chromosome into large fragments. Restriction enzymes utilizing recognition sites containing 6-, 7-, or 8-base-pair sequences with only G and C nucleotides produced few fragments, most of which were greater than 100 kilobase pairs in size. Addition of the fragments from digests of SmaI, NotI, ApaI, RsrII, and EagI yielded a molecular size for the S. mutans GS-5 genome of 2,819 +/- 60 kilobase pairs.

Chromosomes, Bacterial↗