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PubMed1992

Nucleotide sequence of Streptococcus mutans superoxide dismutase gene and isolation of insertion mutants.

A gene (sod) encoding superoxide dismutase (SOD) was cloned from Streptococcus mutans in Escherichia coli, and its nucleotide sequence was determined. The presumptive amino acid sequence of its product revealed that the SOD is basically of Mn type. Insertional inactivation of the sod gene resulted in the loss of SOD activity in crude extracts, indicating that the gene represents the only functional gene for SOD in S. mutans. Moreover, Southern blot analysis indicated that the S. mutans chromosome had no additional gene which was hybridizable with an oligonucleotide probe specific for an SOD motif. The SOD-deficient mutants were able to grow aerobically, albeit more slowly than the parent strains.

Amino Acid Sequence↗
PubMed1993

[The effect of antibody to Streptococcus mutans in saliva on caries activity and S. mutans adhering].

An indirect enzyme-linked immunosorbent assay (ELISA) was used for measuring IgA antibody to whole cell of Streptococcus mutans (serotype c) in saliva. 36 parotid salivary samples of human were collected from two groups: Caries free (CF) and caries sensitive (CS). The result shows that the IgA antibody to S. mutans in CF group was higher than those in CS group (P < 0.05). The saliva antibody was gained from the rabbits by injection with S. mutans (serotype c), and the adhesion of S. mutans--3H on the surface of hydroxylapatite beads treated by rabbit's saliva was measured. The results show that the saliva with immunity could inhibit the S. mutans to adhere on the HA beads (P < 0.05). It means saliva antibody may prevent caries through inhibition of S. mutans from adhesion.

Adult↗
PubMed1983

Virulence of beta-hemolytic and non-hemolytic Streptococcus mutans: lethal dose determinations in neonatal mice.

The virulence of beta-hemolytic and non-hemolytic strains of Streptococcus mutans was studied in neonatal mice by LD50 determinations after intracerebral injection of the bacteria. Although the differences in LD50 values are small the results may indicate that beta-hemolytic S. mutans strains (mean LD50 of 6.3 X 10(7) c.f.u.) were more virulent than non-hemolytic S. mutans strains (mean LD50 of 47.7 X 10(7) c.f.u.). The LD50 values of other viridans streptococci varied between 4.8 and 10(7) c.f.u. Strains of S. pyogenes and S. agalactiae were highly virulent in this animal model with LD50 values lower than 10(5) c.f.u.

Animals↗
PubMed1993

Chromosome organization of Streptococcus mutans GS-5.

Twenty-eight genetic loci have been physically mapped to specific large restriction fragments of the Streptococcus mutans GS-5 chromosome by hybridization with probes of cloned genes or, for transposon-generated amino acid auxotrophs, with probes for Tn916. In addition, restriction fragments generated by one low-frequency-cleavage enzyme were used as probes to identify overlapping fragments generated by other restriction enzymes. The approach allowed construction of a low resolution physical map of the S. mutans GS-5 genome using restriction enzymes ApaI (5'-GGGCC/C), SmaI (5'-CCC/GGG), and NotI (5'-GC/GGCCGC).

Blotting, Southern↗
PubMed1989

Genetic and antigenic comparison of Streptococcus mutans fructosyltransferase and glucan-binding protein.

The genes for fructosyltransferase (ftf) and glucan-binding protein (gbp) of Streptococcus mutans strain Ingbritt have been cloned in E. coli using bacteriophage and plasmid vectors. A single ftf gene appears to be responsible for the appearance of several FTF of different electrophoretic mobilities. Despite the fact that both ftf and gbp proteins synthesise fructans from sucrose in S. mutans and shown closely similar electrophoretic mobilities and isoelectric points, the restriction maps of the two genes are distinct, their DNAs do not hybridise and there is no immunological cross-reaction between the two proteins.

Antigens, Bacterial↗
PubMed1986

Characterization of genetic transformation in Streptococcus mutans by using a novel high-efficiency plasmid marker rescue system.

We developed a marker rescue system for study of competence development and genetic transformation in Streptococcus mutans. The system involved the recombinational rescue of a tetracycline resistance (Tcr) determinant by a homologous, inactive locus (Tcs because of a small deletion). Streptococcal cells harboring this in vitro-prepared Tcs construct (pVA1208) were restored to Tcr when plasmid (pVA981) DNA was used as donor material. pVA981 contained the intact streptococcal Tcr locus and was unable to autonomously replicate in streptococci. Marker rescue with this system followed first-order kinetics and occurred at a frequency 8- or 160-fold higher than did transformation with homologous chromosomal or plasmid DNA, respectively. By using the rescue system, we were able to confirm that competence of S. mutans appeared to be inducible. This was indicated by a sequential increase and then decrease in Tcr transformation frequencies during growth in complex medium. Also, donor DNA binding was not sequence specific, since the recovery of Tcr transformants was reduced by increasing the concentrations of heterologous DNA. We investigated the fate of donor DNA and the kinetics of plasmid establishment in the transformation of S. mutans with plasmid DNA. Monomeric plasmid molecules transformed S. mutans as a second-order process, whereas multimeric plasmid DNA and chromosomal markers were recovered as a first-order process. Approximately 50% of the initially bound donor plasmid DNA was found to remain in a trichloroacetic acid-insoluble form. Our results suggested that molecular cloning in S. mutans would be conducted most efficiently by using helper plasmid systems or shuttle vectors and that gene transfer by transformation of S. mutans occurred in a manner similar to that observed in Streptococcus sanguis.

DNA Restriction Enzymes↗
PubMed1992

Isolation, characterization, and nucleotide sequence of the Streptococcus mutans mannitol-phosphate dehydrogenase gene and the mannitol-specific factor III gene of the phosphoenolpyruvate phosphotransferase system.

Streptococcus mutans, the causative agent of dental caries, utilizes carbohydrates by means of the phosphoenolpyruvate-dependent phosphotransferase system (PTS). The PTS facilitates vectorial translocation of metabolizable carbohydrates to form the corresponding sugar-phosphates, which are subsequently converted to glycolytic intermediates. The PTS consists of both sugar-specific and sugar-independent components. Complementation of an Escherichia coli mtlD mutation with a streptococcal recombinant DNA library allowed isolation of the mannitol-1-phosphate dehydrogenase gene (mtlD) and the adjacent sugar-specific mannitol factor III gene (mtlF) from S. mutans. Subsequent transposon mutagenesis of the complementing DNA fragment with Tn5seq1 defined the region that encodes the mtlD-complementing activity, the streptococcal mtlD gene. Nucleotide sequence analysis of this region revealed two complete open reading frames (ORFs) from within the streptococcal mannitol PTS operon. One ORF encodes the mtlD gene product, a 43.0-kDa protein which exhibits similarity to the E. coli and Enterococcus faecalis mannitol-1-phosphate dehydrogenases. The second ORF encodes a 15.8-kDa protein which exhibits similarity to mannitol factor III proteins from several bacterial species. In vitro transcription-translation assays were used to produce proteins of the sizes predicted by the streptococcal ORFs. These data indicate that the S. mutans mannitol PTS utilizes an enzyme II-factor III complex similar to the mannitol system found in other gram-positive organisms, as opposed to that of E. coli, which utilizes an independent enzyme II system.

Amino Acid Sequence↗
PubMed1979

Fractionation and properties of glucans produced by Streptococcus mutans.

Water-insoluble (ISG) and water-soluble (SG) fractions of glucans produced by cell-free glucosyltransferase of Streptococcus mutans AHT (serotype g) were isolated by centrifugation at 20,000 x g for 15 min. No further resolution of slightly sonicated ISG was observed with gel filtrations on any Bio-Gel beads, including A-50m. Bio-Gel P-100 filtration subdivided SG into two fractions with higher and lower molecular weights (designated SG-A and SG-B, respectively). SG-A was further resolved into two subfractions, SG-A-I and SG-A-II, by 10 to 40% and 50 to 80% ethanol precipitation, respectively. Relative amounts of ISG, SG-A-I, SG-A-II, and SG-B were 66.3:9.4:4.4:19.9. The molecular sizes of these fractions were >1.5 x 10(7), >==1.5 x 10(7), <==5 x 10(6) (>1 x 10(5)), and <==1 x 10(4) daltons, and their alpha-1,3 glucosidic linkage contents were approximately 35, 35, 16, and 4% for fractions ISG, SG-A-I, SG-A-II, and SG-B, respectively. Both ISG and SG-A-I were resistant to hydrolysis by dextranase and possessed the ability to aggregate with concanavalin A and to agglutinate S. mutans cells. SG-A-II had extremely low dextranase susceptibility and significant agglutinating activities, whereas SG-B showed high dextranase sensitivity and neither aggregating nor agglutinating activity. These results indicate that SG of S. mutans AHT consists of three types of glucans with distinctly different molecular sizes and chemical structures and strongly suggest that the ISG and SG-A-I fractions are different physical states of an inherently identical glucan. Preliminary observations suggest that the glucans produced by other S. mutans strains of several serotypes may be similarly classified.

Agglutination↗
PubMed2005

Use of hand held photopolymerizer to photoinactivate Streptococcus mutans.

OBJECTIVES: The main focus of this research was to investigate the photodynamic therapy (PDT), in vitro, acting on Streptococcus mutans and fibroblasts. A hand held photopolymerizer (HHP) and a classical photosensitizer (Rose Bengal) were used to induce photodynamic response. METHODS: S. mutans and fibroblast were treated with different concentrations of Rose Bengal (0-50 microM) irradiated with light (400-500 nm) for different time periods (0-40s) and then cell viability was evaluated. RESULTS: It was observed that the light (per se) is not toxic and in the dark Rose Bengal is toxic to the cells tested only at concentrations above 2.5 microM. Under light exposure concentrations of Rose Bengal above 0.5 microM all S. mutans were killed with no cytotoxic effects to fibroblasts. CONCLUSIONS: For the purpose of this work, the photoactivation of Rose Bengal, using the HHP, inactivated the bacteria without affecting the fibroblast viability.

Bacteriological Techniques↗
PubMed1975

Effective immunity to dental caries: protection of gnotobiotic rats by local immunization with Streptococcus mutans.

Gnotobiotic rats injected in the submandibular region with killed, whole Streptococcus mutans cells developed salivary antibodies directed to this microorganism. Increased levels of salivary IgA and inhibition and augmentation of agglutinin titers with anti-rat alpha-antiglobulin suggested that these antibodies were of the immunoglobulin A class. Furthermore, the rats monoinfected and immunized with homologous organisms always had lower mean caries scores than monoinfected, non-immunized rats. This reduction was evident in carious lesions on the buccal surfaces of molars and in those in sulcal areas. These results suggest that local immunization with whole S. mutans cells stimulates a specific salivary IgA response protective against caries resulting from S. mutans infection.

Agglutination Tests↗
PubMed1999

Variables affecting salivary Streptococcus mutans counts in a cohort of 12-year-old subjects.

BACKGROUND: Several factors such as toothbrushing, diet, acidogenic potential of the mutans streptococci strain and site of the carious lesion can modify the salivary Streptococcus mutans (Sm) counts. In the present investigation the effect of some behavioural, clinical and microbiological variables on Sm salivary counts was evaluated in a cohort of 12-year-olds. METHODS: Forty subjects were examined by two calibrated examiners (GC, AL). The number of surfaces either decayed occlusal, decayed smooth or filled and the number of bleeding sextants, (clinical index for oral hygiene) were reported. Saliva was collected using a tongue depressor and was plated onto mitis salivarius agar with bacitracin and 20% sucrose. The presumptive Sm colonies were counted and the concentrations were logarithmically transformed. One Sm strain per subject was identified and the cariogenic potential evaluated as the minimum pH value recorded, during 5 hrs of incubation in 5% sucrose solution. The children's parents or guardians completed a questionnaire concerning the frequency of toothbrushing, the consumption of sweet foods and soft drinks and at what age the children started brushing their teeth. The effect of the explanatory variables on Sm count logarithms was evaluated by stepwise multiple regression. RESULTS: The regressors with significant additional explanatory power were cariogenic potential (b = -1.335, p = 0.00001, R2 increment = 0.312), decayed smooth surfaces (b = -0.456, p = 0.009, R2 increment = 0.114) and bleeding sextants (b = -0.113, p = 0.004, R2 increment = 0.062), whereas the power of filled surfaces was marginally significant (p = 0.08). CONCLUSIONS: On the basis of these results, it is suggested that acidogenicity is not only a cariogenic factor, but also a factor promoting colonization of oral sites by Sm, especially in subjects with a high frequency of sugar consumption.

Age Factors↗
PubMed1986

A Streptococcus mutans superoxide dismutase that is active with either manganese or iron as a cofactor.

The superoxide dismutase produced by Streptococcus mutans OMZ176 during aerobic growth in a chemically defined medium (modified FMC) that was treated with Chelex 100 (to lower trace metal contamination) and supplemented with high purity manganese was purified (162-fold) by heat treatment, ammonium sulfate precipitation, and chromatofocusing chromatography. The superoxide dismutase produced during aerobic growth in the same medium, but without manganese and supplemented with high purity iron, was similarly purified (220-fold). The molecular masses of each holoenzyme were approximately 43,000 with a subunit mass of 20,700, indicating that the enzymes were dimers of two equally sized subunits. The superoxide dismutase from manganese-grown cells was a manganese enzyme (MnSOD) containing 1.2 atoms of manganese and 0.25 atoms of iron/subunit. The superoxide dismutase from iron-grown cells was an iron enzyme (FeSOD) containing 0.07 atoms of manganese and 0.78 atoms of iron/subunit. The amino acid compositions of the MnSOD and the FeSOD were virtually identical, and their amino-terminal sequences were identical through the first 22 amino acids. Dialysis of the FeSOD with o-phenanthroline and sodium ascorbate generated aposuperoxide dismutase with 94% loss of activity; subsequent dialysis of apoenzyme with either manganese sulfate or ferrous sulfate reconstituted activity (recoveries of 37 and 30%, respectively). Electrophoretic determination of cytoplasmic radioiron distribution indicated that (during aerobic growth) manganese prevented insertion of iron into superoxide dismutase, although the iron levels of at least two other cytoplasmic fractions were not altered by manganese. Therefore, S. mutans used the same aposuperoxide dismutase to form either FeSOD or MnSOD, depending upon which metal was available in the culture medium. Such "cambialistic" enzymes (those capable of making a cofactor substitution) may represent a previously unrecognized family of superoxide dismutases.

Aerobiosis↗
PubMed2000

Adherence of Streptococcus mutans to an E-glass fiber-reinforced composite and conventional restorative materials used in prosthetic dentistry.

The adherence of Streptococcus mutans to E-glass used in fiber-reinforced composites, denture base polymer, and four other restoratives was investigated. The materials were studied with and without a parotid saliva and serum pellicle. Specimens of the studied materials (E-glass, denture base polymer, titanium, cobalt-chromium alloy, gold alloy, and grained feldspar ceramic) were incubated in a suspension of S. mutans, allowing initial adhesion to occur. The degree of bacterial adhesion was studied using scanning electron microscopy (SEM). The studied uncoated materials showed rather similar adhesion of S. mutans. Saliva coating resulted in a decrease of adherence to all materials except glass. With a saliva pellicle E-glass showed the strongest ability to bind S. mutans, and it differed significantly from the other studied materials. Serum coating markedly decreased adhesion to all materials, and only minor differences among the studied materials were observed. The results of this study suggest that the studied restoratives are rather similar with respect to S. mutans adhesion and that a saliva pellicle may promote adhesion of S. mutans to glass fibers.

Bacterial Adhesion↗
PubMed1984

Inter-serotype comparison of polysaccharides produced by extracellular enzymes from Streptococcus mutans.

The biochemical and morphological characteristics of polysaccharides synthesized from sucrose by extracellular enzymes from D-glucose-grown Streptococcus mutans representing serotypes a-g were compared. The polysaccharides synthesized by the enzymes from serotypes a, d, and g formed visible aggregates and firmly adhered to glass surfaces, whereas those formed by the enzymes from serotypes b, c, e, and f floated homogeneously and were poorly adherent. The enzymes of serotypes a, d, and g produced large amounts of water-insoluble polysaccharides (IPs, D-glucans), and those of serotypes b, c, e, and f water-soluble polysaccharides (SPs, D-glucans and D- fructans ). As compared with the IPs of serotypes b, c, e, and f, the IPs of serotypes a, d, and g (a) contained a higher proportion of (1----3)-alpha-D-glucosidic linkages and alpha-D-(1----3,6) branch linkages; (b) showed higher susceptibility to (1----3)-alpha-D-glucanase (serotype a excepted) and lower (1----6)-alpha-D-glucanase sensitivity; (c) contained larger amounts of high-molecular-weight fractions; (d) showed higher intrinsic viscosities (serotype b excepted); and (e) had lower S. mutans cell-agglutination activities. On electron-microscope observation, the IPs of all serotypes showed two fibrillar components; a double-stranded fibril, with short, fluffy protrusions extending out of its periphery, and a fine, single-stranded fibril. Thus, the serotypes could be divided into two major groups: a, d, and g; and b, c, e, and f. No similar grouping of serotypes was indicated by the chemical and morphological properties of SPs.

Polysaccharides↗
PubMed1976

Characterization of an anti-glucosyltransferase serum specific for insoluble glucan synthesis by Streptococcus mutans.

An anti-glucosyltransferase serum, which synthesized 96% insoluble glucans, was prepared against a purified enzyme preparation from Streptococcus mutans strain HS6 (serotype a). This serum was examined for its effects on glucan synthesis by crude enzyme preparations from eight strains (four serotypes) of S. mutans and for the ability of these preparations to promote adherence of S. mutans to a smooth surface. Glucosyltransferase activity was assayed by measuring the incorporation of glucose from [14C]glucose-labeled sucrose into water-insoluble and water-soluble (ethanol-insoluble) glucans. Anti-glucosyltransferase serum inhibited insoluble glucan synthesis by crude enzyme preparations from cells of the four serotypes of S. mutans. Enzymes from strains of types a, b, and d were inhibited between 70 to 90%; enzymes from type c strains were inhibited from 45 to 60%. The adherence to a glass surface of heat-killed cells from these four serotypes was likewise inhibited. Soluble glucan synthesis was not inhibited by the serum, and in some cases its synthesis increased as insoluble glucan synthesis decreased.

Cell Adhesion↗
PubMed1979

Inhibition of adsorption of Streptococcus mutans strains to saliva-treated hydroxyapatite by galactose and certain amines.

Adsorption of all of eight strains of Streptococcus mutans to saliva-treated hydroxyapatite (S-HA) surfaces was inhibited by galactose and melibiose, but not by other neutral sugars tested. This observation supports the hypothesis that lectin-like components participate in the attachment of these streptococci to salivary glycoproteins on saliva-treated hydroxyapatite surfaces. Adsorption of all strains was also inhibited by iodoacetate and spermine; other amines tested reduced adsorption of some strains, but not others.

Adsorption↗