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PubMed2001

Effect of carbon starvation and proteolytic activity on stationary-phase acid tolerance of Streptococcus mutans.

Previous research with Streptococcus mutans and other oral streptococci has demonstrated that the acid shock of exponential-phase cells (pH 7.5 to 5.5) resulted in the induction of an acid tolerance response (ATR) increasing survival at low pH (3.5-3.0). The current study was designed to determine whether two fresh isolates, H7 and BM71, and two laboratory strains, Ingbritt and LT11, were capable of a stationary-phase ATR as estimated by a survival test at pH 3.5 for 3 h. All four strains were unable to generate a stationary-phase ATR under control conditions at pH 7.5, with the exception of a burst of survivors in the transition between the exponential and stationary phases when the carbon source (glucose) was depleted. Adaptation at pH 5.5 resulted in the expected pH-dependent exponential-phase ATR, but only the fresh isolates exhibited a stationary-phase ATR at this pH. Glucose starvation of cells in complex medium was shown to enhance acid tolerance for the fresh isolates, but not the laboratory strains. This tolerance was, however, greatly diminished for all strains in a defined medium with a low concentration of amino acids. Growth of strain H7 in complex medium resulted in the formation of at least 56 extracellular proteins, nine of which were degraded in the early stationary phase following the induction of proteolytic activity during the transition period. No proteolytic activity was observed with strain LT11 and only 19 extracellular proteins/peptides were apparent in the medium with only one being degraded in the early stationary phase. Strain H7 was also shown to have two- to fourfold higher levels of intracellular glycogen in the stationary phase than strain LT11. These results suggest that S. mutans H7 possessed the required endogenous metabolism to support amino acid/peptide uptake in the early-stationary phase, which resulted in the formation of basic end products that, in turn, contributed to enhanced intracellular pH homeostasis.

Adaptation, Physiological↗

PubMed1979

Purification and antigenic properties of intracellular invertase from Streptococcus mutans.

Intracellular invertase from Streptococcus mutans GS5 was purified to near homogeneity by gel filtration and ion-exchange chromatography followed by preparative polyacrylamide gel electrophoresis. The invertase appeared to be composed of a single polypeptide chain with a molecular weight of 48,000. Extracellular invertase was identified in strain GS5 and was determined to have a molecular weight of 500,000. No antigenic relationship between these two forms of invertase was observed since antibody prepared against purified intracellular invertase neither affected extracellular invertase activity nor precipitated that enzyme on immunodiffusion. No antigenic relatedness between intracellular invertase and glucosyl- and fructosyl- transferases was detected since cross-reactivity with antibody prepared against either enzyme fraction was not observed after immunodiffusion. Using immunodiffusion and quantitative precipitin data, we examined the relationships of other S. mutans intracellular invertases to the serotype c enzyme. It appeared that the intracellular invertases from serotypes e, f, and g were structurally similar to the enzyme from serotype c, whereas the structure of invertases from serotypes a, b, and d appeared less similar to that of enzyme from serotype c.

Dental Plaque↗

PubMed2004

[The inhibitive effect of IgY toothpaste against oral Streptococcus mutans].

PURPOSE: To study the effect of the toothpaste containing IgY against oral Streptococcus mutans. METHODS: 140 subjects were divided into 2 groups randomly (test group and control group). Before the beginning of the test, every subject underwent a elution period in order to lessen the other interference factors, then used different toothpastes were used respectively and the test began. Streptococcus mutans values were determined with Dentocult SM Strip just before test, at 1, 3, 7, 30 days after toothpaste used and 14 days after stopping toothpaste used. RESULTS: (1) In test group,Streptococcus mutans values decreased at 1 day after toothpaste used. In control group Streptococcus mutans values decreased at 3 days after toothpaste used. (2) Streptococcus mutans values decreased gradually in each groups after toothpaste used. (3) In test group, 2 weeks after stopping toothpaste used, Streptococcus mutans values were still suppressed. CONCLUSION: The application of the toothpaste containing IgY may reduce oral Streptococcus mutans levels significantly.

Child↗

PubMed2004

The rational design of an anti-caries peptide against Streptococcus mutans.

The cariogenic bacterium Streptococcus mutans attaches to tooth surfaces via a cell surface adhesin termed streptococcal antigen I/II (SA I/II). Mapping studies identified an adhesion epitope within residues 1025-1044. A synthetic peptide (p1025) spanning these residues inhibited adhesion of S. mutans in vitro and was tested in an in vivo human streptococcal adhesion model. Direct application of p1025 to the teeth prevented recolonisation of the oral cavity by S. mutans but not Actinomyces naeslundii. This review also describes various other adhesion-inhibiting peptides have been identified in vitro. We suggest that adhesion-blocking synthetic peptides may provide novel anti-infective agents. Topical application of such peptides at mucosal surfaces does not provide sustained selective pressure and in contrast to antibiotics, may not induce resistance.

Amino Acid Sequence↗

PubMed1976

Purification and immunochemical characterization of type e polysaccharide antigen of Streptococcus mutans.

The type-specific antigen of Streptococcus mutans strain MT703, serotype e, has been chromatographically purified and characterized. Two chromatographic fractions were obtained from saline extracts which reacted with both anti-MT703 whole-cell serum and Lancefield group E serum. The major fraction (eI) was identified as a polysaccharide composed of 37% glucose, 56% rhamnose, 5% protein, and 0.3% phosphorus, whereas the minor fraction (eII) contained 66% protein in addition to 10% glucose and 17% rhamnose. The immunological specificity of these antigens was found to be the same by immunodiffusion in agar gel. Another fraction with a negative charge (eIII) reacted with polyglycerophosphate antisera from Streptococcus mutans and Streptococcus pyogenes. For comparison, the MT703 antigen in a hot trichloroacetic acid extract (eA) and the group E antigen from a saline extract of cells of strain K129 (EI) were similarly purified by anionic ion-exchange chromatography. Although the ratio of glucose and rhamnose in eA was 1:0.9 and in eI and eII approximately 1:1.5, reactions of identity were obtained in gel diffusion against specific anti-e serum. This difference in ratio is probably a result of the extraction procedures. Both the type e and group E antisera were reactive with both eI and EI antigens. The adsorption of group E antiserum with MT703 cells removed all E antibody, whereas type e-specific antibody remained after adsorption with K129 cells. These results suggest that eI antigen possesses both e and E specificities, whereas EI possesses E only. These findings were supported by the quantitative precipitin test and immunodiffusion and/or immunoelectrophoretic patterns in agar gel. Methyl-beta-D-glucopyranoside markedly inhibited the precipitin reaction in both type e and group E sera. However, a significantly stronger inhibition by cellobiose of type e serum than of group E serum indicates that a beta-linked glucose-glucose dimer is the predominant antigenic determinant of the e specificity. The presence of both e and E specificities on a single polysaccharide molecule was demonstrated by the use of purified e antigen released from a specific e-anti-e complex. This antigen reacted with a group E-specific serum as well as a type e-specific serum. An examination of five S. mutans type e strains showed the presence of group E specificity also, whereas the I, II, and IV serotypes of group E streptococci only possessed the group E specificity.

Antigens, Bacterial↗

PubMed1978

Induction of secretory antibodies in humans following ingestion of Streptococcus mutans.

1) Ingestion of Streptococcus mutans antigen by human volunteers induced the selective appearance of antibodies in saliva and tears but not in serum. 2) These antibodies were associated with the IgA class as determined by enhanced or blocked agglutination, immunofluorescence and gel filtration. 3) A second series of antigen ingestion resulted in a secondary response in these secretions characterized by an earlier appearance of antibodies which reached higher titers than in the primary response.

Administration, Oral↗

PubMed1995

Analysis of glucan synthesis by Streptococcus mutans.

Glucan synthesis by Streptococcus mutans GS-5 has been analyzed by examining the regulation of expression and structure-function relationships of the glucosyltransferases. Primer extension analysis of the gtf genes has identified the putative promoter sequences for these genes and indicated that the -10 sequences are similar to the Escherichia coli consensus sequence. Site-directed mutagenesis as well as deletion analysis of the enzymes have identified amino acid residues as well as functional domains which play important roles in glucan synthesis.

Adhesins, Bacterial↗

PubMed1998

Genes involved in cell wall localization and side chain formation of rhamnose-glucose polysaccharide in Streptococcus mutans.

We identified in Streptococcus mutans six new genes (rgpA through rgpF), whose disruption results in a loss of serotype-specific antigenicity, specified by the glucose side chains of rhamnose-glucose polysaccharide from the cell wall. Rhamnose and glucose content of the cell wall decreased drastically in all these disruption mutants, except that in the rgpE mutant only the glucose content decreased. RgpC and RgpD are homologous to ATP-binding cassette transporter components and may be involved in polysaccharide export, whereas RgpE may be a transferase of side chain glucose.

Amino Acid Sequence↗

PubMed1978

Combined extracellular sucrolytic enzyme power from a strain of Streptococcus mutans, and purification results.

Streptococcus mutans has been shown to produce extracellular invertase, dextransucrase, and levansucrase. The purpose of this work was to study the relative quantities of these enzymes in pure culture supernatant, and in samples from commonly used purification methods. The strain "Ingbritt" was selected because it is a well-defined human strain, available, and with well-known growth requirements. The samples were incubated with sucrose for the determination of free monohexoses, and the polysaccharide from ethanol precipitation was hydrolyzed as previously described. In cell supernatant the inversion effect exerted 75% of total sucrolytic power, the dextransucrase 20% and the levansucrase 5%. No method, tested in this work, could separate all the activities completely.

Ammonium Sulfate↗

PubMedDate not supplied

Chromosomal insertions and deletions in Streptococcus mutans.

Many isolates of Streptococcus mutans lack the ability to ferment melibiose and other sugars. We previously reported that this was commonly due to a chromosomal deletion and, in the present study, sequence information from the S. mutans genome project was used to design PCR primers to explore the nature and extent of the deletion. In all melibiose-negative strains examined, there was an incomplete insertion element, ISSmu3, in place of the 18-kb stretch of chromosome encoding the msm and GAL operons. Strains that were also unable to utilise beta-glucosides were found to have a separate 4 kb deletion in the BGL regulon that is proposed to be due to homologous recombination between two short stretches of identical sequence. The evidence is consistent with all the melibiose-negative strains examined being derived from a common ancestor.

Chromosome Deletion↗

PubMed1990

[Comparative study of the adherence test and the Petry plaque count test of Streptococcus mutans in saliva].

The Streptococcus mutans counts--added to lactobacili depicting test--are an useful instrument in cariology when determining the risk groups. In studies concerning a large number of patients the S. Mutans count in saliva test are the most accesible. Nevertheless, they are very expensive and also complicate to carry out. Simplified techniques which depict S. Mutans on the basis of adherence tests have been perfected. The most suitable from them, taking into account our working conditions, is the Matsukubo test. We deemed it interesting to correlate this test and the Gold medium count. The study has been carried out with three different populations using both techniques at the same time. As per the correlation indices obtained we conclude that the Matsukubo technique and the count have a significant correlation between them. Due to its low cost, the simplicity of its realization, as well as its easy reading it can be effectively used as a primary procedure when studying populations large in number. Through this method selection will be made of the patients to be studied applying more precise microbiological techniques.

Adult↗

PubMed1979

Regulation and function of sucrose 6-phosphate hydrolase in Streptococcus mutans.

Sucrose catabolism by Streptococcus mutans is initiated by a phosphoenolpyruvate-dependent sucrose phosphotransferase reaction that produces sucrose 6-phosphate the latter is then cleaved by a sucrose 6-phosphate hydrolase reaction that yields glucose 6-phosphate and fructose. We have examined the regulation of the sucrose 6-phosphate hydrolase and found that it was synthesized constitutively whereas sucrose phosphotransferase activity was inducible. However, the levels of both sucrose phosphotransferase and sucrose 6-phosphate hydrolase were repressed when fructose was used as a growth substrate. The specific activity of sucrose 6-phosphate hydrolase in permeabilized cells was approximately 30 mmol/min per mg (dry weight of cells), and it had an apparent Km for sucrose 6-phosphate of 0.3 mM. analysis of a mutant that was missing sucrose 6-phosphate hydrolase activity revealed that its ability to hydrolyze sucrose was reduced.

Glucosephosphates↗

PubMed1984

The adsorption of human salivary components to strains of the bacterium Streptococcus mutans.

Using strains of Streptococcus mutans suspended in human saliva, the salivary proteins capable of binding to the surface of the bacteria were identified by immunological and electrophoretic techniques. Six binding components were recognized: IgA, lysozyme, some high molecular weight material (greater than 400,000), probably a glycoprotein, a low molecular weight component (11-13,000), a 150,000 mol. wt protein, and one major component, mol. wt 20-25,000 which did not resolve fully on SDS-polyacrylamide electrophoresis. All these salivary components could be desorbed from the bacteria with 1 M NaCl, and subsequent extraction of the same cells with 6 M guanidine-HCl did not release any more salivary material. The significance of the binding of these salivary components is unknown but some may modify the behaviour of the organisms in vivo.

Adsorption↗

PubMed1983

The repressible metabolism of sorbitol (D-glucitol) by intact cells of the oral plaque-forming bacterium Streptococcus mutans.

Sorbitol metabolism of Streptococcus mutans was studied. Cocci adapted to growth in sorbitol, glucose or both were challenged to grow on and to ferment those carbohydrates in pH-controlled defined media with intact cells capable of metabolic inductions and regulations. Glucose degradation when in high concentration did not depend upon induction of glucose-specific phosphoenolpyruvate-dependent phosphotransferase activity, as it did at low glucose concentrations. Sorbitol utilization was signalled by the induction of sorbitol-specific phosphoenolpyruvate-dependent phosphotransferase and sorbitol-6-phosphate dehydrogenase activities which persisted throughout the growth cycle. However, when even low levels of glucose were present, sorbitol transport and catabolic activities were rapidly repressed and they were not de-repressed until essentially all glucose had been utilized. Metabolism of sorbitol thus relies on the sorbitol phosphotransferase/sorbitol-6-phosphate dehydrogenase pathway whose activity is sensitively repressed in the presence of glucose.

Enzyme Repression↗

PubMed1983

Comparative effects of five chlorosucrose analogues on acidogenicity and adherence of the oral bacterium Streptococcus mutans in vitro.

Standardized Streptococcus mutans suspensions were incubated with five chlorosucrose compounds alone and in the presence of sucrose. Fall in pH was recorded over 4 h. Other experiments used image-analysis techniques to measure deposition by sedimentation from similar test suspensions. In the pH experiments, order of acidogenicity was 1'-chlorosucrose or 4,6,6'-trichlorosucrose greater than 1',6'-dichlorosucrose greater than 6,1',6'-trichlorosucrose. The last two compounds statistically significantly reduced fall in pH from metabolism of endogenous carbohydrate. All the chlorosucroses significantly decreased acidogenicity of sucrose; with 6,1',6'-trichlorosucrose and 4,1',6'-trichlorosucrose terminal pH was approximately 1 unit higher than with sucrose alone. In the deposition experiments, all chlorosucroses except 1',6'-dichlorosucrose decreased deposition in the presence of sucrose after either 30 min or 4 h incubation. The greatest reduction in deposition in the presence of sucrose after 4 h was with 6,1',6'-trichlorosucrose or 1'-chlorosucrose.

Adhesiveness↗

PubMed1982

Effects of penicillin on synthesis and excretion of lipid and lipoteichoic acid from Streptococcus mutans BHT.

Cultures of Streptococcus mutans BHT grown for at least eight generations in a chemically defined medium containing [1(3)-14C]glycerol, when treated with growth-inhibitory concentrations (0.2 micrograms/ml) of benzylpenicillin (Pen G), produced and excreted increased amounts of lipid and lipoteichoic acid per unit of cells. Cellular lysis was not observed. Compared with untreated controls, lipid excretion increased 15-fold, and lipoteichoic acid excretion increased 6-fold, 4 h after the addition of Pen G. All lipid species showed increased synthesis and excretion after exposure to Pen G. Although the same lipid types were found in both the Pen G-treated and the untreated cultures, the percent composition was altered after treatment with Pen G. The most dramatic example of this was the percentage of intracellular diphosphatidylglycerol found in the Pen G-treated cultures, 22.6%, in contrast to 5.3% found in the untreated cultures.

Glycerol↗

PubMed1980

Regulation and function of ammonia-assimilating enzymes in Streptococcus mutans.

The ability of Streptococcus mutans to synthesize amino acids was examined. A total of 8 of 12 laboratory strains grew anaerobically on solid-defined medium that contained no amino acids. Several isolates, therefore, assimilated ammonia for the biosynthesis of amino acids. These strains included representatives of five serotypes. One strain, DR0001, was also grown in liquid-defined medium. The enzymes of two pathways by which ammonia can be fixed were detected in this strain DR0001 could use either a reduced nicotinamide adenine dinucleotide phosphate-coupled glutamate dehydrogenase or the combined action of adenosine 5'-triphosphate-driven glutamine synthetase with a reduced nicotinamide adenine dinucleotide-coupled glutamate synthase to assimilate ammonia for the biosynthesis of amino acids. Evidence that both pathways were functional was provided by an analysis of the influence of the nitrogen source on enzyme levels and by the isolation and characterization of glutamate dehydrogenase-negative mutants.

Adenosine Triphosphate↗

PubMed1993

Multiple changes in cell wall antigens of isogenic mutants of Streptococcus mutans.

Isogenic mutants of Streptococcus mutans LT11, deficient in the production of the wall-associated protein antigens A and B, were generated by recombinant DNA technology. The hydrophobicity, adherence, and aggregation of the mutants were compared with those of the parent strain. These studies indicated that hydrophobicity, adherence, and saliva- or sucrose-induced aggregation were unaltered in the A- mutant but that hydrophobicity and adherence to saliva-coated hydroxylapatite were greatly reduced in the B- mutant whilst sucrose-dependent adherence and aggregation were increased. To determine whether these changes correlated with changes in the mutated gene product alone, the levels of a number of cell wall antigens were determined in each of the mutants. The loss of antigen A resulted in significantly reduced levels of wall-associated lipoteichoic acid, and loss of antigen B resulted in reductions in both antigen A and lipoteichoic acid. Data presented here thus suggest that changes in the expression of one wall antigen can have a dramatic effect on the levels of others.

Antigens, Bacterial↗