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PubMed2006

[A study of genetic diversity in lactate dehydrogenase of Streptococcus mutans from clinical isolates].

OBJECTIVES: Lactate dehydrogenase (LDH) is shown to be an important virulence factor resulting in acid production of Streptococcus mutans (S. mutans), on which the cariogenic potential of S. mutans depends. Differences in cariogenic abilities of S. mutans isolates may be determined by genetic heterogeneity from virulent factors. The relationship between LDH activity or genetic diversity and cariogenicity of S. mutans (serotype c) isolates was studied in this research. METHODS: The genome DNA of S. mutans isolates were isolated and LDH gene (ldh) were amplified with specific primers. These isolates came from 34 caries-active individuals and 36 caries-free ones, in which 24 strains showed the high LDH activity and 21 strains showed the low LDH activity. Then genetic diversity of PCR products were analyzed or assessed by restriction fragment-length polymorphism (RFLP). Some of amplified LDH genes from different group were sequenced and assayed. RESULTS: It is testified that two genotypes A and B of ldh-RFLP were revealed when LDH genes were digested with Mse I, but Hph I, Mnl I, Dde I, Nla III and Alu I digesting fragments of Idh gene did not show different pattern. Furthermore, Fisher Exact one-Tail Test showed that the proportion of genotype B among strains from caries-free individuals was higher than that from caries-active ones (P = 0.033), while the distribution of genotypes with different LDH activity was different between two groups (two-Tail Test P = 0.017). The sequencing DNA testified that the specific base mutation would lead to multiple kind of genotype resulted. CONCLUSION: This study indicated that LDH gene of S. mutans clinical strains from different individuals is conservative, while there still is the gene mutation in. The ldh genetic diversity may be related to the low caries sensitivity, and closely correlated with the differences in LDH enzyme activity of S. mutans strains.

DNA, Bacterial↗
PubMed1991

Distribution, persistence, and recall of serum and salivary antibody responses to peroral immunization with protein antigen I/II of Streptococcus mutans coupled to the cholera toxin B subunit.

After peroral immunization of mice with surface protein antigen (Ag) I/II of Streptococcus mutans conjugated to the cholera toxin B (CTB) subunit, cells actively secreting immunoglobulin A (IgA) antibodies specific for Ag I/II, but not for CT, were induced in the salivary glands; salivary IgA anti-Ag I/II antibodies and total salivary IgA were also elevated. The development of large numbers of IgA and IgG antibody-secreting cells in the mesenteric lymph nodes and spleen and high levels of serum IgA and IgG antibodies to Ag I/II and CT demonstrated that a response to both antigens occurred. At least two to three intragastric doses of 15 micrograms or more of Ag I/II-CTB conjugate, plus free CT as an adjuvant, were needed to induce the salivary IgA anti-Ag I/II response, which peaked at about 35 days and persisted at lower levels for 5 to 6 months. A single booster intragastric immunization did not induce enhanced salivary IgA anti-Ag I/II antibodies relative to the primary response, but serum IgA and IgG antibodies to both Ag I/II and CT showed evidence of marked anamnestic responses. The results indicated that relatively long-term mucosal IgA antibody responses could be induced by peroral immunization with small quantities of a CTB-conjugated protein. However, additional factors governed the distribution of cells secreting antibodies of different specificities, or capable of mounting anamnestic responses, between different compartments of the mucosal and circulatory immune systems.

Adjuvants, Immunologic↗
PubMed2002

Analysis of cis- and trans-acting factors involved in regulation of the Streptococcus mutans fructanase gene (fruA).

There are two primary levels of control of the expression of the fructanase gene (fruA) of Streptococcus mutans: induction by levan, inulin, or sucrose and repression in the presence of glucose and other readily metabolized sugars. The goals of this study were to assess the functionality of putative cis-acting regulatory elements and to begin to identify the trans-acting factors involved in induction and catabolite repression of fruA. The fruA promoter and its derivatives generated by deletions and/or site-directed mutagenesis were fused to a promoterless chloramphenicol acetyltransferase (CAT) gene as a reporter, and strains carrying the transcriptional fusions were then analyzed for CAT activities in response to growth on various carbon sources. A dyadic sequence, ATGACA(TC)TGTCAT, located at -72 to -59 relative to the transcription initiation site was shown to be essential for expression of fruA. Inactivation of the genes that encode fructose-specific enzymes II resulted in elevated expression from the fruA promoter, suggesting negative regulation of fruA expression by the fructose phosphotransferase system. Mutagenesis of a terminator-like structure located in the 165-base 5' untranslated region of the fruA mRNA or insertional inactivation of antiterminator genes revealed that antitermination was not a mechanism controlling induction or repression of fruA, although the untranslated leader mRNA may play a role in optimal expression of fructanase. Deletion or mutation of a consensus catabolite response element alleviated glucose repression of fruA, but interestingly, inactivation of the ccpA gene had no discernible effect on catabolite repression of fruA. Accumulating data suggest that expression of fruA is regulated by a mechanism that has several unique features that distinguish it from archetypical polysaccharide catabolic operons of other gram-positive bacteria.

5' Untranslated Regions↗
PubMed2006

DNA fingerprinting of isolates of Streptococcus mutans by pulsed-field gel electrophoresis.

Forty isolates and five standard laboratory strains, representing serotypes c, e and f of Streptococcus mutans were analyzed by pulsed-field gel electrophoresis (PFGE) after digestion of the genomic DNA with BssH II. The digestion patterns of standard laboratory strains were characteristic of serotypes c, e and f. Serotypes c and f generated diagnostic DNA fragments of approximately 145 kbp and of approximately 130-175 kbp in length, respectively. Serotype e generated a ladder of at least 14 fragments of 15-155 kbp in length. The digestion patterns of isolates were essentially similar to those of the standard laboratory strains. The patterns of almost all isolates obtained from a single individual were identical, but patterns of a few different types were also observed among isolates obtained from two individuals. Digestion with BssH II revealed differences among isolates obtained from different individuals. We used differences in banding patterns among isolates to construct a dendrogram. The dendrogram included two major clusters, one that consisted of isolates of serotypes c and f, and an other that consisted of isolates of serotype e. Our results indicate that BssH II is a useful enzyme for distinguishing among isolates of S. mutans and that digestion patterns obtained by PFGE can be used for chromosomal DNA fingerprinting.

Bacterial Typing Techniques↗
PubMed1986

ELISA detection of human IgG subclass antibodies to Streptococcus mutans.

A sensitive enzyme-linked immunosorbent assay (ELISA) has been developed to measure IgG subclass antibodies against whole cells of Streptococcus mutans and to a purified streptococcal antigen (SA I/II). Bacterial cells were bound to the solid phase using methyl glyoxal and mouse monoclonal antisera against IgG and each IgG subclass were used to detect antibodies. Natural antibodies to S. mutans were predominantly of the IgG1 and IgG2 subclasses, though IgG3 and IgG4 antibodies were detectable in most subjects, and were the majority response in a few subjects. Antibodies to SA I/II were predominantly of the IgG1 subclass with virtually no activity detectable in the IgG3 and IgG4 subclasses. Inhibition studies suggested some restriction of IgG subclass responses to bacterial antigens since SA I/II and c polysaccharide could inhibit binding of all subclasses to whole cells of S. mutans equally, whereas glucosyltransferase, lipoteichoic acid and dextran showed greatest inhibition of the IgG3 and IgG4 subclasses.

Antibodies, Bacterial↗
PubMed2002

A quorum-sensing signaling system essential for genetic competence in Streptococcus mutans is involved in biofilm formation.

In a previous study, a quorum-sensing signaling system essential for genetic competence in Streptococcus mutans was identified, characterized, and found to function optimally in biofilms (Li et al., J. Bacteriol. 183:897-908, 2001). Here, we demonstrate that this system also plays a role in the ability of S. mutans to initiate biofilm formation. To test this hypothesis, S. mutans wild-type strain NG8 and its knockout mutants defective in comC, comD, comE, and comX, as well as a comCDE deletion mutant, were assayed for their ability to initiate biofilm formation. The spatial distribution and architecture of the biofilms were examined by scanning electron microscopy and confocal scanning laser microscopy. The results showed that inactivation of any of the individual genes under study resulted in the formation of an abnormal biofilm. The comC mutant, unable to produce or secrete a competence-stimulating peptide (CSP), formed biofilms with altered architecture, whereas the comD and comE mutants, which were defective in sensing and responding to the CSP, formed biofilms with reduced biomass. Exogenous addition of the CSP and complementation with a plasmid containing the wild-type comC gene into the cultures restored the wild-type biofilm architecture of comC mutants but showed no effect on the comD, comE, or comX mutant biofilms. The fact that biofilms formed by comC mutants differed from the comD, comE, and comX mutant biofilms suggested that multiple signal transduction pathways were affected by CSP. Addition of synthetic CSP into the culture medium or introduction of the wild-type comC gene on a shuttle vector into the comCDE deletion mutant partially restored the wild-type biofilm architecture and further supported this idea. We conclude that the quorum-sensing signaling system essential for genetic competence in S. mutans is important for the formation of biofilms by this gram-positive organism.

Bacterial Proteins↗
PubMed2004

Inhibitory effect of some herbal extracts on adherence of Streptococcus mutans.

The objective of this study was to investigate the inhibitory effect of the crude extracts from some herbs on adherence of Streptococcus mutans (S. mutans) ATCC 25175 and TPF-1 in vitro. Six herbs, Andrographis paniculata; Cassia alata; Chinese black tea (Camellia sinensis); guava (Psidium guajava); Harrisonia perforata and Streblus asper, were extracted with 50 or 95% ethanol and dried. Herbal extracted solution at 0.5% concentration (w/v) was initially tested for bacterial adherence on glass surfaces. In order to identify type and effective concentration of the extracts, the extracts that showed the inhibition on glass surfaces were then tested on saliva-coated hydroxyapatite by the use of radiolabeled bacteria. To study the mechanism of action, the effect of the extracts at such concentration on glucosyltransferase and glucan-binding lectin activities were examined. It was found that all extracts, but Streblus asper, showed significant inhibitory effect on bacterial adherence to glass surfaces. For the saliva-coated hydroxyapatite adherence assay, Andrographis paniculata, Cassia alata, Chinese black tea and Harrisonia perforata could inhibit adherence of S. mutans ATCC 25175. Chinese black tea was the strongest inhibitor followed by Andrographis paniculata, Cassia alata and Harrisonia perforata, respectively. For S. mutans TPF-1, adherence inhibition was observed from Andrographis paniculata and Cassia alata at similar levels. The lowest concentrations of the extracts that inhibited the adherence at least 50% were 0.5% of Andrographis paniculata, 0.5% of Cassia alata, 0.3% of Chinese black tea and 0.5% of Harrisonia perforata for S. mutans ATCC 25175. For S. mutans TPF-1, the effective concentrations were 0.5% of Andrographis paniculata and 0.4% of Cassia alata. All extracts at such concentrations decreased the activity of glucosyltransferase from both strains. Only Andrographis paniculata and Cassia alata eliminated or decreased the activity of glucan-binding lectin from both strains. These findings suggested that Andrographis paniculata, Cassia alata, Chinese black tea and Harrisonia perforata could inhibit adherence of S. mutans ATCC 25175, while Andrographis paniculata and Cassia alata had an effect on S. mutans TPF-1 in vitro at the concentrations employed in this study.

Bacterial Adhesion↗
PubMed1985

Promotion of Streptococcus mutans glucose transport by human whole saliva and parotid fluid.

Human saliva and parotid fluid have two effects on glucose uptake by Streptococcus mutans: a reduction in the overall rate of uptake, and the promotion of a biphasic mode of uptake. The former effect had been previously shown to result from lactoperoxidase-mediated inhibition of transport or metabolism or both. The objective of the present study was to uncover the basis of the second effect. Biphasic glucose uptake consisted of a rapid phase of low capacity and short duration (approximately 10 to 15 s) followed by a slower phase of high capacity and long duration (several minutes). The slow phase is typical of cells not exposed to the secretions (control cells). S. mutans BHT cells pretreated with as little as 10 microM glucose for 10 min at 37 degrees C, followed by its removal, subsequently exhibit biphasic glucose uptake typical of saliva- or parotid fluid-treated cells. Since pretreatment of the organism with glucose, whole saliva supernatant, or parotid fluid supported subsequent transport of the nonmetabolized glucose analog, 2-deoxyglucose, we concluded that pretreatments established a relatively stable pool of glycolytic intermediates (i.e., a phosphoenolpyruvate potential). Thin-layer chromatographic analysis of extracts from [14C]glucose-pretreated cells confirmed the presence of a stable pool of triose phosphates. Dialysis experiments indicated that high-molecular-weight substrates in the secretions were readily utilized by the organism to establish a phosphoenolpyruvate potential, especially when the lactoperoxidase system was rendered inactive. A survey of several carbohydrate constituents of salivary glycoproteins revealed that mannose, galactose, and N-acetylglucosamine, in addition to glucose, established phosphoenolpyruvate potentials in the organisms. Inactive substances included, among others, N-acetylgalactosamine and N-acetylneuraminic acid. In a survey of selected amino acids, arginine alone promoted 2-deoxyglucose accumulation by the organism, albeit feebly. Finally, it is argued that the phenomenon of biphasic glucose uptake provides evidence that the rate limiting step in glucose uptake by S. mutans is glucose metabolism and not glucose transport.

Amino Acids↗
PubMed1989

Genetic diversity within Streptococcus mutans evident from chromosomal DNA restriction fragment polymorphisms.

Attempts to study the acquisition, transmission, and other aspects of the natural history of Streptococcus mutans infections in humans have been hampered by limitations and inconsistencies in methods by which phenotypic characteristics of individual isolates are examined. Because most mutans streptococci associated with human dental caries fall within the biotype I (serotypes c and f) grouping, designated S. mutans, these typing methods are of little value in distinguishing individual isolates. Here we show that strains of S. mutans obtained from over 30 individuals demonstrate unique "fingerprints" of chromosomal DNA digested with restriction endonuclease HaeIII. To demonstrate that this polymorphism in restriction fragments can be used to study the acquisition and transmission of this organism, we examined isolates of S. mutans from three mother-infant pairs obtained at the time the infant first became colonized by this organism. Results indicate that strains of S. mutans found in infants exhibit restriction fragment profiles identical to those of their mothers, strongly supporting the notion that mothers transmit this organism to their infants. Also, we show that strains of S. mutans with the same restriction fragment profile were stably maintained over a 3-year interval in the one mother-infant pair studied. Moreover, we found that mothers and their infants harbored only a few individual strains, suggesting that transmission of this organism is probably confined within discrete family cohorts. Collectively, these findings demonstrate the potential utility of genomic fingerprinting in studying the natural history of S. mutans infections in humans.

Bacteriocins↗
PubMed1978

Growth inhibition of Streptococcus mutans and Leuconostoc mesenteroides by sodium fluoride and ionic tin.

Sodium fluoride caused inhibition of growth rate and growth levels of Streptococcus mutans with glucose as the primary energy and carbon source. Stannous fluoride increased growth lag nad caused a much greater inhibition of growth rate than did sodium fluoride. Neither compound was found to be bactericidal when culture viability was measured after 6 days of incubation. Leuconostoc mesenteroides, which lacks a phosphotransferase system for sugar transport, showed less inhibition of growth rate with both inhibitors than did S. mutans, which possesses a phosphotransferase system. Metabolism of glucose or lactose which requires enolase activity shoed sodium fluoride inhibition, whereas metabolism of arginine or pyruvate does not involve enolase activity and showed no inhibition of growth.

Dental Caries↗
PubMed1976

In vitro effects of low concentrations of penicillin and sulfadiazine on Streptococcus mutans.

Investigations were conducted to determine the in vitro effects of low levels of penicillin and sulfadiazine on the growth, plaque formation, and agglutination of Streptococcus mutans and on the synthesis and activity of enzymes synthesizing extracellular polymers. The concentrations tested were equivalent to those expected in the saliva of subjects receiving oral therapy with the agents. Penicillin at 0.5 ng/ml and sulfadiazine at 1 mug/ml substantially inhibited in vitro plaque formation. At these concentrations, sulfadiazine but not penicillin also inhibited growth of the organism. Neither antimicrobial agent affected the agglutination of S. mutans with dextran or the synthesis or activity of enzymes synthesizing extracellular polymers. The effect of sulfadiazine on plaque formation was attributed, at least in part, to the inhibitory action of that agent on S. mutans growth.

Hemolytic Plaque Technique↗
PubMed1978

Streptococcus mutans dextransucrase: stimulation of glucan formation by phosphoglycerides.

Lysophosphatidylcholine (LPC) and other phosphoglycerides stimulated water-insoluble and water-soluble glucan production by the Streptococcus mutans 6715 dextransucrase (EC 2.4.1.5). LPC stimulated crude extracellular dextransucrase 1.7-fold, the water-insoluble glucan-producing alpha form of the enzyme 6.5-fold, the water-soluble glucan-producing beta form of the enzyme 2.1-fold, and the cell-associated dextransucrase 2.0-fold. Kinetic studies demonstrated that LPC did not change the K(m) for sucrose of alpha or beta but increased the maximum velocity of the enzymes. The K(m) for LPC of the alpha enzyme was 10(-5) M. LPC from various sources and synthetic preparations of lauroyl-LPC, myristoyl-LPC, and palmitoyl-LPC all stimulated glucan formation. Portions of phosphoglyceride molecules including fatty acids, phosphatidic acid, glycerophosphoric acid, glycerophos-phorylcholine, and choline, when tested individually or in combinations, did not enhance dextransucrase activity. The increased rates of glucan production caused by LPC and primer dextran were additive. Enzyme incubated with LPC before addition of sucrose was stimulated by dextran primer, and, conversely, enzyme treated with dextran was stimulated by addition of LPC with the sucrose substrate. Thus, dextransucrase can be activated by binding of intact phosphoglyceride molecules to a site on the enzyme that is distinct from either the glucosyl donor or glucosyl acceptor (primer) binding sites. Interactions between the S. mutans dextransucrase and amphipathic phosphoglycerides may explain properties of this enzyme which contribute to the cariogenicity of S. mutans.

Dextrans↗
PubMed2004

Inactivation of the ciaH Gene in Streptococcus mutans diminishes mutacin production and competence development, alters sucrose-dependent biofilm formation, and reduces stress tolerance.

Many clinical isolates of Streptococcus mutans produce peptide antibiotics called mutacins. Mutacin production may play an important role in the ecology of S. mutans in dental plaque. In this study, inactivation of a histidine kinase gene, ciaH, abolished mutacin production. Surprisingly, the same mutation also diminished competence development, stress tolerance, and sucrose-dependent biofilm formation.

Bacteriocins↗
PubMed1986

An improved medium for isolation of Streptococcus mutans.

A medium based upon tryptone, yeast extract, cystine (TYC) agar and incorporating bacitracin and sucrose has been evaluated for selective isolation of Streptococcus mutans. The effect of varying the concentrations of sucrose and bacitracin on the recovery of two standard strains was investigated. Growth of S. mutans NCTC 10449 was significantly inhibited by increasing concentrations of sucrose but was not affected by bacitracin; the reverse was seen with S. sobrinus strain 6715. The best compromise between recovery of the streptococci and growth of other organisms was obtained with a final sucrose concentration of 20% and bacitracin 0.2 units/ml. In comparison with three other selective media, this medium gave the highest recovery rate of standard strains, indicating that it is superior to mitis-salivarius bacitracin (MSB) agar for the recovery of S. mutans from saliva.

Adult↗
PubMed1987

Recognition of carbohydrate and protein epitopes by monoclonal antibodies to a cell wall antigen from Streptococcus mutans.

The nature of the determinants recognized by a panel of monoclonal antibodies (MAbs) raised against a cell wall antigen of Streptococcus mutans (SA I/II) was investigated. Mild periodate oxidation of SA I/II showed that MAbs Guy 1, 2, 3, and 5 recognized carbohydrate epitopes on the antigen. Glycosidases were used to identify the nature of the sugars involved in their binding. Treatment with beta-glucosidase inhibited the binding of Guy 1, 2, 3, and 5 by 90%. No competition was found for any of the MAbs between SA I/II and a series of carbohydrates, including the serotype c polysaccharide from S. mutans. The results show that MAbs Guy 1, 2, 3, and 5 recognize carbohydrate epitopes on SA I/II which are distinct from the serotype polysaccharide. The other MAbs recognized protein epitopes on SA I/II.

Antibodies, Bacterial↗
PubMedDate not supplied

[Relations between sodium fluoride sensitivity and cariogenic potential in Streptococcus mutans].

Supragingival plaque samples of a group of 59 schoolchildren were taken. The samples were cultivated on a selective medium for Streptococcus mutans and the isolated wild strains were tested for resistance to sodium fluoride (NaF). The results show the existence of a positive statistic correlation between the degree of resistance to NaF caries experience, obtained by DMFS of the experimental group.

Adolescent↗
PubMed1983

Detection of antibodies against Streptococcus mutans cell wall contaminating sera against ribosomal fractions.

A modification of the immunoprecipitation technique was developed to precipitate ribosomal proteins from Streptococcus mutans in isoelectric focusing gels. The method was established in order to determine whether the ribosomal immunogen was contaminated with cell surface proteins. Isoelectric focusing was used to separate the proteins into bands in the gel and various antisera utilized to precipitate the antigens. Electrophoresis of the ribosomal preparation produced 19 protein bands. A rat antiserum raised against the preparation reacted with 8 of these bands and an aliquot of the same antiserum which had been adsorbed with whole S. mutans cells reacted with only 6 bands. This procedure allowed us to detect contamination of the ribosomal preparation with cell surface antigens. The method may be used to detect contamination with cell surface antigens in many different subcellular preparations.

Animals↗