PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Streptococcus mutans”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 397 records · Page 22Linked to original sources
PubMed2004

[The effects of natural medicine on adherence of Streptococcus mutans to salivary acquired pellicle].

OBJECTIVE: To investigate the effects of 5 kinds of natural medicine such as Radix et Rhizoma Rhei on the adherence of Streptococcus mutans to salivary acquired pellicle, and to screen effective natural medicines for the prevention of caries. METHODS: The in vitro model of experimental pellicle was saliva-coated hydroxyapatites (S-HA). Streptococcus mutans and S-HA were treated with natural medicines respectively, and then the adherence of bacteria to S-HA was tested. RESULTS: Radix et Rhizoma Rhei, Semen Arecae and Rhizoma Liguistici Chuanxiong could decrease the attachment of Streptococcus mutans to S-HA, and Semen Arecae was the most effective one. Radix Angelicae Dahuricae had no remarkable effect, and Catechu inhibited the adherence only after the bacteria being under treatment. CONCLUSION: Radix et Rhizoma Rhei, Semen Arecae, Rhizoma Liquistici Chuanxiong and Catechu could effectively inhibit the adherence of Streptococcus mutans to salivary acquired pellicle, but the effect of Radix Angelicae Dahuricae on the adherence is un-noticeable.

Areca↗
PubMed2000

Three-dimensional modelling of the catalytic domain of Streptococcus mutans glucosyltransferase GtfB.

Glucosyltransferases (GtfB/C/D) of Streptococcus mutans, a pathogen for human dental caries, synthesize water-insoluble glucan through the hydrolysis of sucrose. Genetic and biochemical approaches have identified several active sites of these enzymes, but no three-dimensional (3D) structural evidence is yet available to elucidate the subdomain arrangement and molecular mechanism of catalysis. Based on a combined sequence and secondary structure alignment against known crystal structures of segments from closely related proteins, we propose here the 3D model of an N-terminal domain essential for the sucrose binding and splitting in GtfB. A Tim-barrel of (alpha/beta)(8) structural characteristics is revealed and the structural correlation for two peptides is described.

Amino Acid Sequence↗
PubMed1977

Effect of Tween 80 on glucosyltransferase production in Streptococcus mutans.

Glucan production from sucrose by Streptococcus mutans OMZ 176 was stimulated approximately threefold in the presence of 0.1% Tween 80. When OMZ 176 was grown in a medium containing glucose, the glucosyltransferase level in the medium was also increased about fivefold in the presence of 0.1% Tween 80. The glucosyltransferase level increased in proportion to the logarithm of the concentration of Tween 80 in the glucose medium. Tween 80 affected neither bacterial growth nor the activity of glucosyltransferase. The appearance of glucosyltransferase in the glucose medium was inhibited immediately by chloramphenicol and actinomycin D and, after a lag, by rifampin as well. It was observed that the fatty acid composition of the cells grown with Tween 80 was altered. These results suggest that Tween 80 stimulates glucosyltransferase synthesis either directly, or indirectly by promoting glucosyltransferase secretion.

Chloramphenicol↗
PubMed1993

Transformation efficiency of EMS-induced mutants of Streptococcus mutans of altered cell shape.

Some Streptococcus mutans strains change shape from bacillary to coccal or ellipsoid form in response to the ratio of bicarbonate to potassium or of borate to potassium in growth media. So that insight into determinants of shape of these streptococci could be gained, and future genetic studies facilitated, the shapes of a series of transformable and nontransformable strains of S. mutans were studied and attempts made to isolate a mutant of augmented transformability. Several strains were mutagenized by ethylmethane sulfonate and mutants with altered colonial and cellular morphologies isolated. Cell shapes were studied by Gram stain and Nomarski interference microscopy, and by scanning and transmission electron microscopy. Diverse shape-altered mutants were isolated from seven transformable and two nontransformable strains of S. mutans. Among these, length-to-width ratios ranged from > 10 to about 0.25. Regulation of timing of cell division, septum formation, or septum completion events may have been altered in these mutants. While most mutants substantially or completely lost transformability, mutant LT11 had transformation efficiency of 1.3 x 10(-4) to 2.3 x 10(-3), more than two to three orders of magnitude greater than its parental UA159 and the well-known transformable strain GS5(HK), respectively. There was no evidence of production of competence factor by LT11. Competence of LT11 was maintained for at least six months upon storage at -70 degrees C, facilitating its use for genetic studies. While the morphologies of several shape-altered mutants were no longer responsive to changes of the bicarbonate/potassium, unlike those of their parentals, the morphology of LT11 persisted in its response to this condition.(ABSTRACT TRUNCATED AT 250 WORDS)

Ethyl Methanesulfonate↗
PubMed1996

Characterization of an unusual fluoride-resistant Streptococcus mutans isolate.

A fluoride-resistant Streptococcus mutans isolate NCH105 was characterized and compared with wild-type strain UA130. The growth and lactic acid production of strain NCH105 were found to be unaffected by the presence of fluoride at the initial medium pH values of 6.5 and 6. In addition, NCH105 was found to be capable of lowering the pH of the medium to approximately 5.5, which is the critical level where enamel demineralization begins in vivo. Lactic acid production, glucose uptake at pH 6.5 and 6, as well as ATPase activity at pH 5 were found to be unaffected by fluoride. Finally, strain NCH105 is capable of binding as well as the wild-type bacterium to artificial tooth pellicles. These results are unusual when compared with previously isolated fluoride-resistant mutants and suggest that NCH105 may have the ability to colonize the tooth surface and initiate dental caries.

Adenosine Triphosphatases↗
PubMed1991

Effect of whole saliva on the rheologic behavior of extracellular water-soluble glucan produced by Streptococcus mutans.

The viscosity of mixtures of Streptococcus mutans water-soluble glucan and stimulated whole saliva or buffer was measured at pH 5, 6, 7, and 8. The viscosity was measured as a function of shear rate in the range 15 s-1-230 s-1. Though the centrifuged saliva had a viscosity close to that of water it increased the viscosity of the glucan up to 65% at pH 6 and 55% at pH 7 and at a shear rate of 20 s-1, indicating an interaction between saliva components and glucan that could be an important part of the cohesive forces of plaque matrix. The interaction between saliva and glucan was less pronounced at pH 5 and 8, which indicates a charge-dependent interaction. The viscosity increase at pH 6 and 7 was higher at low than at high shear rates, suggesting a higher contribution to plaque stability when weak as opposed to high mechanical forces are exerted on the plaque.

Buffers↗
PubMed1995

Interaction of chlorhexidine with cytoplasmic membranes of Streptococcus mutans GS-5.

Cytoplasmic membranes of Streptococcus mutans GS-5 were extracted by incubating cells with 1% sodium lauroyl sarcosinate for 20 min at room temperature. The profiles of membrane proteins were determined by SDS-PAGE and isoelectric focusing. The effect of chlorhexidine digluconate on cell membranes was studied after treating the extracted proteins for 30 min with the drug at final concentrations of 0.05 and 0.2%. Chlorhexidine caused selective reduction in the intensity of the membrane proteins. Five densely staining bands with molecular weights of 24.2, 19.6, 18.1, 17.6 and 16.4 kD were obviously diminished. Isoelectric focusing indicated that chlorhexidine preferably precipitated acidic cytoplasmic proteins (pI 4.0-4.92). Our results are consistent with the hypothesis that the mode of action of this drug is mainly attributed to its hydrophilic property. Chlorhexidine, being cationic, may interact with bacteria by attraction to negative-charge membrane components.

Adenosine Triphosphatases↗
PubMed2002

Genome sequence of Streptococcus mutans UA159, a cariogenic dental pathogen.

Streptococcus mutans is the leading cause of dental caries (tooth decay) worldwide and is considered to be the most cariogenic of all of the oral streptococci. The genome of S. mutans UA159, a serotype c strain, has been completely sequenced and is composed of 2,030,936 base pairs. It contains 1,963 ORFs, 63% of which have been assigned putative functions. The genome analysis provides further insight into how S. mutans has adapted to surviving the oral environment through resource acquisition, defense against host factors, and use of gene products that maintain its niche against microbial competitors. S. mutans metabolizes a wide variety of carbohydrates via nonoxidative pathways, and all of these pathways have been identified, along with the associated transport systems whose genes account for almost 15% of the genome. Virulence genes associated with extracellular adherent glucan production, adhesins, acid tolerance, proteases, and putative hemolysins have been identified. Strain UA159 is naturally competent and contains all of the genes essential for competence and quorum sensing. Mobile genetic elements in the form of IS elements and transposons are prominent in the genome and include a previously uncharacterized conjugative transposon and a composite transposon containing genes for the synthesis of antibiotics of the gramicidin/bacitracin family; however, no bacteriophage genomes are present.

Base Sequence↗
PubMed2006

Regulation and physiologic significance of the agmatine deiminase system of Streptococcus mutans UA159.

We previously demonstrated that Streptococcus mutans expresses a functional agmatine deiminase system (AgDS) encoded by the agmatine-inducible aguBDAC operon (A. R. Griswold, Y. Y. Chen, and R. A. Burne, J. Bacteriol. 186:1902-1904, 2004). The AgDS yields ammonia, CO2, and ATP while converting agmatine to putrescine and is proposed to augment the acid resistance properties and pathogenic potential of S. mutans. To initiate a study of agu gene regulation, the aguB transcription initiation site was identified by primer extension and a putative sigma70-like promoter was mapped 5' to aguB. Analysis of the genome database revealed an open reading frame (SMU.261c) encoding a putative transcriptional regulator located 239 bases upstream of aguB. Inactivation of SMU.261c decreased AgD activity by sevenfold and eliminated agmatine induction. AgD was also found to be induced by certain environmental stresses, including low pH and heat, implying that the AgDS may also be a part of a general stress response pathway of this organism. Interestingly, an AgDS-deficient strain was unable to grow in the presence of 20 mM agmatine, suggesting that the AgDS converts a growth-inhibitory substance into products that can enhance acid tolerance and contribute to the competitive fitness of the organism at low pH. The capacity to detoxify and catabolize agmatine is likely to have major ramifications on oral biofilm ecology.

Agmatine↗
PubMed1986

Comparative studies on the protein profiles and hydrophobicity of strains of Streptococcus mutans serotype c.

Twelve strains of Streptococcus mutans serotype c were grown in batch culture with glucose at constant pH (6.0) and a number of properties compared. On the basis of their cellular and extracellular protein profiles, the strains were divided into three groups, I, II and III, containing five, four and three strains, respectively. The extracellular protein profiles for a particular strain differed if the organisms were grown either at pH 6.0 with fructose instead of glucose or with glucose but without pH control. The total amount of extracellular protein produced by group III strains grown in glucose-containing medium at pH 6.0 was several times that produced by strains of groups I and II, which were also more hydrophobic. One of the potentially important proteins is P1, also called antigen B or I/II, and it was shown to be entirely in the culture fluid of group III strains but mostly cell-associated from strains of groups I and II. Approximately half of the cell-associated fraction of P1 could be removed with hot sodium dodecyl sulphate.

Bacterial Proteins↗
PubMed1983

Effect of xylitol and other carbon sources on the cell wall of Streptococcus mutans.

Transferring actively growing bacteria of Streptococcus mutans ATCC 27351 into a xylitol-containing reaction mixture caused distinct alterations in bacterial ultrastructure without notable effect on the total viability of the strain. Incubations in media containing 50 mg/ml of glucose, fructose, sucrose, lactose, sorbitol or mannitol as the primary carbon source did not affect bacterial ultrastructure. These fermentations were reflected biochemically in the amounts of insoluble glucans, as expected. A negative correlation was found between the cell mass and the lipoteichoic acid formation. But these aspects could not be visualized in the electron microscope. In the xylitol series, however, degrading cells and autolysis, intracellular vacuoles and lamellated formations in the cytoplasmic membrane were frequently seen independent of the concentration of xylitol in the reaction mixtures. In freeze-fracturing replicas, however, the membrane intercalated particles of the cytoplasmic membranes seemed to be unaffected and like those in the controls. Minor ultrastructural changes in the fracture-faces were detected. Despite the alterations in ultrastructure of the xylitol-incubated bacteria, there was no difference in their viability when compared to the controls.

Carbohydrates↗
PubMed2001

Complete nucleotide sequence and characterization of pUA140, a cryptic plasmid from Streptococcus mutans.

Approximately 5% of strains of Streptococcus mutans contain plasmid DNA. Strain UA140 harbors a 5.6-kb cryptic plasmid, pUA140, with an overall G+C content of 32.7%. Five open reading frames (ORF), encoding peptides of larger than 100 amino acid residues, were initially designated as ORF1 to ORF5. These five ORFs were located on the same strand of pUA140. ORF1 (258 amino acids) resembled a replication protein, Rep. Upstream of the putative Rep gene, a double-stranded origin for plasmid replication that showed strong similarity to those of a number of plasmids in the pT181 family was identified. Further upstream was a region constituting the single-stranded origin of replication. A single-stranded DNA intermediate was detected during plasmid replication. Taken together, these results suggest that pUA140 replicated by the rolling circle replication mechanism but exhibited several characteristics that differ from those of other members of the pT181 plasmid family.

Amino Acid Motifs↗
PubMed1992

Mechanism of Streptococcus mutans glucosyltransferases: hybrid-enzyme analysis.

Streptococcus mutans GS5 expresses three glucosyltransferases (GTFs): GTF-I and GTF-SI, which synthesize water-insoluble glucans in a primer-independent manner, and GTF-S, which is responsible for the formation of primer-dependent soluble glucan. The amino acid sequences of the GTF-I and GTF-S enzymes exhibit approximately 50% sequence identity. Various hybrid genes were constructed from the structural genes for the enzymes, and their products were analyzed. Three different approaches were used to construct the hybrid enzymes: (i) ligation of DNA fragments containing compatible endonuclease restriction sites of the two genes at homologous positions; (ii) in vivo recombination between the homologous regions of each gene; and (iii) random fusion of DNA fragments from each gene generated following exonuclease III digestion of tandemly arranged fragments corresponding to the two functional domains of each enzyme. Hybrid GTFs composed of the sucrose-binding domain of one enzyme (GTF-I or GTF-S) with the glucan-binding domain of the other synthesized insoluble glucan exclusively in the absence of primer dextran. Insoluble glucan synthesis by some, but not all, of the GTF-S:GTF-I chimeric enzymes was stimulated by primer dextran T10 addition. In addition, glucan binding by the former but not latter group of hybrid GTFs was demonstrated. These results suggest that the glucan-binding domain alone does not solely determine primer dependence or independence or the structure of the resulting glucan product, although this carboxyl-terminal domain containing direct repeating units does appear to play a significant role in primer dependence.

Amino Acid Sequence↗
PubMedDate not supplied

[Presence of biotypes of "Streptococcus mutans group" in the mouth of Belgrade children].

Strains of "Streptococcus mutans group" were tested in order to determine their belonging to the biotype according to the scheme suggested by Shklair. Biochemical testing of the strains was performed by API 20 Strep system. All the strains tested in this experiment showed biochemical activity characteristic for Streptococcus mutans, Biotype I, Genetic group I, and serological groups (c, e, f). The results of this research are in accordance with the results of similar works performed in various geographical areas.

Bacterial Typing Techniques↗
PubMed1981

Localization of Streptococcus mutans GS-5 glucosyltransferases and intracellular invertase.

Antibodies directed against Streptococcus mutans GS-5 intracellular invertase and glucosyltransferase fractions capable of synthesizing primarily water-soluble or insoluble glucans were used to ultrastructurally localize the enzymes by means of the unlabeled antibody peroxidase-antiperoxidase method. This immunocytochemical procedure revealed that the intracellular invertase was associated primarily with the cytoplasmic membrane of the cariogenic organism. The glucosyltransferase complex responsible for insoluble glucan synthesis was localized as aggregates attached to the cell surface or extracellular polysaccharides of strain GS-5. In contrast, the glucosyltransferase activity synthesizing primarily water-soluble glucans was distributed uniformly over the cell surface or in association with extracellular polysaccharides. These results are discussed relative to the sucrose-metabolizing ability of Streptococcus mutans.

Cell Membrane↗
PubMed2000

[Effect of calcium on adherence of Streptococcus mutans MT6R(serotype c) surface protein P1].

OBJECTIVE: To study effects of calcium on the adherence of Streptococcus mutans MT6R(serotype c) surface protein P1 to saliva-coated hydroxyapatite(S-HA). METHODS: The surface protein P1 of Streptococcus mutans MT6R was purified by PAGE and labeled with 131I(131I-P1). The adherence amount of 131I-P1 to S-HA in different calcium concentration liquid was measured. RESULTS: The amount of 131I-P1 adherence to S-HA in 0, 0.1, 0.25, 0.5, 1.0, 1.5, 2.0 mmol/L, and calcium was 7175 + 183, 7516 + 192, 8850 + 215, 9335 + 204, 10087 + 228, 10179 + 224 and 10200 + 317 cpm, respectively(P < 0.01). The calcium concentration from 0 to 1.0 mmol/L, the amount of 131I-P1 adherence was increased statistically(P < 0.05), calcium concentration from 1.0 mmol/L to 2.0 mmol/L, the amount of 131I-P1 adherence was increased unstatistically(P > 0.05). CONCLUSION: Calcium promoted the adherence of surface protein P1 to the S-HA. This result suggested that calcium was involved in the adherence of Streptococcus mutans MT6R (serotype c) surface protein P1.

Bacterial Adhesion↗
PubMed1998

Effect of sucrose and glucose on the susceptibility of Streptococcus mutans to cephalosporins.

The effect of the type of sugar used as substrate on the susceptibility of Streptococcus mutans to antibiotics was evaluated. Thirty strains, grown in excess of sucrose (s-MIC) and in excess of glucose (g-MIC), were tested for susceptibility to four cephalosporins. About 21% of the strains were sensitive in the presence of sucrose and resistant in the presence of glucose, whereas only 3% of the strains showed the opposite situation. The mean values of the s-MICs of the four cephalosporins were significantly lower than those of the g-MICs. These findings may also be explained by the synthesis, in excess of sucrose, of insoluble glucan by Streptococcus mutans which increases the interbacterial distance and promotes antibiotic diffusion. Given the susceptibility of Streptococcus mutans grown in excess of sucrose to cefotaxime and cefepime, these antibiotics may be used in the primary prevention of infective endocarditis, when subjects predisposed to endocarditis need invasive dental therapy.

Anti-Bacterial Agents↗