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PubMed1983

Oxygen metabolism of Streptococcus mutans: uptake of oxygen and release of superoxide and hydrogen peroxide.

Oxygen (O2) uptake and release of O2 metabolites to the extracellular medium were studied with representatives of serotypes a through g of Streptococcus mutans. When incubated with glucose, washed cells of all strains took up O2 at rates proportional to the O2 concentration. When O2 was held constant at 0.2 mM, 0.2 to 0.5 mol of O2 was taken up per mol of glucose metabolized. Despite the similar rates of O2 uptake, the strains fell into three classes according to the amount of hydrogen peroxide (H2O2) released. Strains BHT, FA-1, and OMZ-176 released up to 90% of O2 taken up as H2O2, which accumulated in the medium to concentrations as high as 2 mM. The high levels of H2O2 accumulation were correlated with low ability to reduce exogenous H2O2 to water. Strains Ingbritt and B-13 released about half as much H2O2, but H2O2 in the medium did not exceed 0.05 to 0.1 mM. Strains HS-6, AHT, GS-5, OMZ-175, LM-7, and 6515-15 released less than 10% of O2 taken up as H2O2, and H2O2 did not accumulate. Within this class, strains HS-6 and AHT released about 6% of O2 taken up as superoxide (O2-). Release of O2 metabolites was correlated with enzyme activities in cell-free extracts. Extracts from all strains catalyzed NADH-dependent O2 uptake. Extracts from H2O2-accumulating strains produced H2O2 when incubated with NADH and O2 and had low ability to catalyze NADH-dependent reduction of H2O2. Extracts from HS-6 and AHT had low superoxide dismutase activity, which may account for O2- release and the O2-sensitive growth of these strains.

Hydrogen Peroxide↗

PubMed1990

Characterization of leukocyte chemotactic activity of bacteriocin from Streptococcus mutans Rm-10.

Bacteriocins have several biological activities in addition to their antibacterial effect. We investigated the chemotactic properties and mode of action of purified streptococcal bacteriocin. Bacteriocin purified from a culture supernatant of Streptococcus mutans (S. mutans) Rm-10 induced chemotaxis of human polymorphonuclear leukocytes and monocytes. Following purification, leukocyte migration appeared in one bacteriocin fraction, and this migration was dependent on the concentration gradient in dilution ranges from 1/960 to 1/15. Chemotactic activity of the bacteriocin was heat labile and trypsin sensitive. Moreover, preincubation of bacteriocin with varying dilutions of its antiserum prepared in rabbits resulted in a significant loss of the chemotactic activity.

Bacteriocins↗

PubMed1997

Antigenic characterization of fimbria preparations from Streptococcus mutans isolates from caries-free and caries-susceptible subjects.

The adhesion of pathogenic bacteria to the host surface is an essential step in the development of numerous infections, including dental caries. Attachment of Streptococcus mutans, the main etiological agent of human dental caries, to the tooth surface may be mediated by glucan synthesized by glucosyltransferase (GTF) and by cell surface proteins, such as P1, which bind to salivary receptors. Fimbriae on the surfaces of many microorganisms are known to function in bacterial adhesion. Previous studies in this laboratory have initially characterized the fibrillar surface of S. mutans. The purpose of this investigation was the comparison of the antigenic properties of fimbria preparations of S. mutans isolates from five caries-resistant (CR) and six caries-susceptible (CS) subjects. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of S. mutans fimbrial preparations revealed five major protein bands at 200, 175, 157, 86, and 66 kDa in preparations from CR and CS subjects. Immunoblot analysis indicated the presence of the same major bands recognized by anti-S. mutans fimbria antisera. Furthermore, the 175- and 157-kDa bands were recognized by antibodies to P1 and GTF, respectively. Immunoblot analysis with antisera to the fimbria preparation, to P1, or to GTF indicated that the levels of fimbria-reactive components and P1 and GTF antigens were higher in S. mutans fimbria preparations from CS subjects than in those from CR individuals. For example, four of six fimbria preparations from CS patients had demonstrable P1, and all had GTF. In contrast, only two of five CR fimbrial preparations exhibited P1 and GTF. Enzyme-linked immunosorbent assay demonstrated similar results for levels of GTF antigen in the fimbrial preparations from CR and CS subjects. The results suggest that differences between the compositions of S. mutans fimbriae in CR and CS individuals may play an important role in the virulence of this microorganism in dental caries.

Adolescent↗

PubMed1988

Uptake of saccharin and related intense sweeteners by Streptococcus mutans NCTC 10449.

In a 1-octanol/phosphate buffer system, saccharin was much more lipophilic than would be inferred from its dissociation constant which, however, determined the partition behavior of acesulfame and cyclamate. The uptake of saccharin into Streptococcus mutans led to a 30 to 40-fold higher concentration of this intense sweetener within cells than in the incubation medium. Acesulfame and cyclamate were distributed between cells and medium essentially in a diffusion-controlled manner. The uptake of saccharin into S. mutans was found to depend strongly on simultaneous sugar fermentation, and in addition, on external pH, sweetener concentrations, and cell densities. Without glycolysis, caused, for example, by an exhaustion of added sucrose, too acidic external pH, or the addition of glycolysis inhibitors, the uptake of saccharin was diffusion-controlled as in the case of acesulfame and cyclamate. The uptake of saccharin was inhibited by a reversal of the direction of the lactate gradient from in----out to out----in. The activation energy of saccharin uptake into glycolyzing S. mutans was near 18 kJ/mol, while glycolysis itself required 82-98 kJ/mol as activation energy, depending somewhat on experimental conditions. Up to 100 attomol of saccharin per bacterial cell was observed. It was concluded that the cytomembrane of S. mutans was involved in mediating the inhibitory effects of saccharin by an antiport of saccharin into cells in exchange for lactate.

Chromatography, High Pressure Liquid↗

PubMed1977

In vitro enamel demineralization by Streptococcus mutans in the presence of salivary pellicles.

Salivary pellicles developed on extracted teeth favorably affected the degree and nature of enamel demineralization when the teeth were incubated in vitro with either of two pure strains of cariogenic Streptococcus mutans. The mechanism responsible for this protection may relate to the permselective properties of these salivary pellicles.

Dental Caries↗

PubMed1974

Interdental localization of Streptococcus mutans as related to dental caries experience.

The consistency of colonization of tooth surfaces by Streptococcus mutans was studied by sampling four approximal molar surfaces of 9- to 13-year-old children at weekly intervals. It was found that surfaces which harbored detectable levels of the organism tended to be consistently positive, whereas surfaces which were free of detectable levels of the organism also tended to remain that way. Of the total surfaces studied, 81.7% were either consistently positive or consistently negative throughout five consecutive weekly samplings. These data indicate that S. mutans does not uniformly colonize the surfaces of teeth. The consistent localized patterns of colonization observed suggest that S. mutans is not readily transmitted from one tooth surface to another within the mouth. Scanning electron microscope observations revealed that S. mutans colonized the teeth of monoinfected gnotobiotic rats as discrete localized colonies, whereas strains of Actinomyces naeslundii colonized in a more generalized manner. Efforts to sterilize tooth surfaces by application of iodine solution indicated that the populations of S. mutans on some surfaces could be affected for at least 11 to 13 weeks after treatment. The number of tooth surfaces colonized by detectable proportions of S. mutans was found to be far lower in a group of 18 children from Charlotte, N.C., with a low past caries experience than in 20 children from Danvers, Mass., with a high caries experience. The number of tooth surfaces infected with S. mutans therefore strongly paralleled the caries experience of these populations.

Actinomyces↗

PubMed1985

Effects of extracellular plaque components on the chlorhexidine sensitivity of strains of Streptococcus mutans and human dental plaque.

An in vitro study was undertaken to determine the effects of sucrose-derived extracellular plaque components on the sensitivity of selected oral bacteria to chlorhexidine (CX). Cultures of Streptococcus mutans HS-6, OMZ-176, Ingbritt C, 6715-wt13, and pooled human plaque were grown in trypticase soy media with or without 1% sucrose. The sensitivity to CX of bacteria grown in each medium was determined by fixed-time exposure to CX and subsequent measurement of 3H-thymidine uptake. One-hour exposure to CX at concentrations of 10(-4) M (0.01% w/v) or greater substantially inhibited subsequent cellular division among all the S. mutans strains and human plaque samples tested. An IC50 (the CX concentration which depressed 3H-thymidine incorporation to 50% of control level) of close to 10(-4) M was noted for S. mutans strains HS-6, OMZ-176, and 6715-wt13 when grown in the presence of sucrose. The same strains grown in cultures without added sucrose showed about a ten-fold greater sensitivity to CX (IC50 close to 10(-5) M). A three-fold difference was noted for S. mutans Ingbritt C. Only a slight increase in the IC50 was noted for the plaque samples cultured in sucrose-containing media, but their threshold for depression of 3H-thymidine uptake by CX was lower than that for the sucrose-free plaque samples. The study showed that extracellular products confer some protection against CX to the bacteria examined, and provided an explanation for the disparity between clinically-recommended concentrations for plaque suppression and data on in vitro susceptibility.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed2005

Removal of Streptococcus mutans biofilm by bubbles.

BACKGROUND: Air bubbles had been shown to remove particles and bacteria from surfaces, but they had not yet been studied regarding the removal of mature biofilm from a surface. METHODS: Streptococcus mutans were grown as a biofilm on glass coverslips and were exposed to a fluid stream with or without bubbles. Three parameters (stream velocity, gas fraction, and bubble size) were varied in the bubble stream to determine which conditions best remove the biofilm. RESULTS: At low velocities bubbles enhance biofilm removal compared with the liquid alone. Stream conditions that were shown to be the most effective in removing biofilm were large bubbles at low gas fractions. CONCLUSIONS: These results suggest that flowing bubble streams may be a desirable feature to incorporate into oral hygiene products to remove accumulated biofilms such as dental plaque.

Air↗

PubMed1991

Restriction fragment length polymorphisms and sequence variation within the spaP gene of Streptococcus mutans serotype c isolates.

A restriction fragment length polymorphism study was undertaken to determine the extent and location of heterogeneity within spaP encoding the Mr 185,000 cell surface protein P1 (antigen I/II) of Streptococcus mutans serotype c isolates. The gene was found to be highly conserved except for a central variable (V) region predicted to encode less than 150 amino acids. Sequence analysis identified two V-region variants. These differences were independent of the geographic source of the isolates. Southern analysis using synthetic oligonucleotide probes indicated that nonretention of P1 (I/II) by some isolates is not due to a deletion of the 3'-terminal DNA necessary to encode an intact carboxy terminus.

Antigens, Bacterial↗

PubMed2006

Calorimetric comparison of the interactions between salivary proteins and Streptococcus mutans with and without antigen I/II.

Antigen I/II can be found on streptococcal cell surfaces and is involved in their interaction with salivary proteins. In this paper, we determine the adsorption enthalpies of salivary proteins to Streptococcus mutans LT11 and S. mutans IB03987 with and without antigen I/II, respectively, using isothermal titration calorimetry. In addition, protein adsorption to the cell surfaces was determined spectrophotometrically. S. mutans LT11 with antigen I/II, yielded a much higher, exothermic adsorption enthalpy at pH 6.8 (ranging from -2073 x 10(-9) to -31707 x 10(-9) microJ per bacterium) when mixed with saliva than did S. mutans IB03987 (-165 x 10(-9) to -1107 x 10(-9) microJ per bacterium) at all bacterial concentrations studied (5 x 10(9), 5 x 10(8), and 5 x 10(7) ml(-1)), largest effects per bacterium being observed for the lowest concentration. However, the enthalpy of salivary protein adsorption to S. mutans LT11 became smaller at pH 5.8. Adsorption isotherms for the S. mutans LT11 showed considerable protein adsorption at pH 6.8 (1.2 - 2.1 mg/m(2)), that decreased only slightly at pH 5.8 (1.1 - 1.6 mg/m(2)), with the largest amount adsorbed at the lowest bacterial concentration. This suggests that the protein(s) in the saliva with the strongest affinity for antigen I/II is (are) readily depleted from saliva. In conclusion, antigen I/II surface proteins on S. mutans play a determinant role in adsorption of salivary proteins through the creation of enthalpically favorable adsorption sites.

Antigens, Bacterial↗

PubMed1982

In vitro susceptibility of streptococcus mutans 6715 to iodine and sodium fluoride, singly and in combination, at various pH values.

The effect of pH on minimal bactericidal concentrations (MBCs) of sodium fluoride (NaF) and iodine (I2), singly and in combination, for Streptococcus mutans 6715 was investigated by using an in vitro checkerboard broth dilution assay. As pH was decreased, lower concentrations of NaF and I2 were required to exert a bactericidal effect. There was statistically significant linear correlation between pH and the MBCs of NaF (r = 0.95, P less than 0.001) and I2 (r ;.92, P less than 0.001). The MBCs of NaF were more affected by a change in pH than were the MBCs of I2; for every decrease of one pH unit in the range of pH 5 to 8, the MBC of NaF decreased fourfold, and the MBC of I2 decreased twofold. NaF and I2 in combination exhibited bactericidal effects on S. mutans which were additive at all pH values tested. These data indicated that the antibacterial properties of I2 and NaF, singly or in combination, can be enhanced by acidification.

Drug Interactions↗

PubMed2006

Immunogenicity of Salmonella vector vaccines expressing SBR of Streptococcus mutans under the control of a T7-nirB (dual) promoter system.

The purpose of the present study was to determine if a Salmonella vector expressing the cloned saliva-binding region (SBR) of Streptococcus mutans or SBR linked to the A2 and B subunits of cholera toxin (CTA2/B) under the control of both the T7 and nirB promoters (T7-nirB dual promoter) was more effective in inducing mucosal and systemic anti-SBR antibody responses than Salmonella clones expressing the same antigens but under the control of either the nirB or T7 promoter. Mice were immunized by the intranasal route on days 0, 18 and 320 with Salmonella enterica serovar Typhimurium strain BRD 509 containing one of six plasmids encoding SBR or SBR-CTA2/B under the control of the T7-nirB, T7, or nirB promoter. Serum, saliva and vaginal wash samples were collected throughout the experiment and assessed for antibody activity by ELISA. Evidence is provided that Salmonella clones expressing SBR or SBR-CAT2/B under the control of either the T7 or T7-nirB promoter induced a high and persistent mucosal and systemic anti-SBR antibody response. All Salmonella clones induced good anti-SBR responses following the boost on day 320.

Animals↗

PubMed1983

Effective immunity to dental caries: enhancement of salivary anti-Streptococcus mutans antibody responses with oral adjuvants.

In the present study, we compared the ability of the soluble adjuvants concanavalin A (ConA), muramyl dipeptide (MDP), and peptidoglycan (PG) to enhance immune responses to orally administered particulate antigens of Streptococcus mutans 6715 in gnotobiotic rats. The isotype and levels of antibody in saliva and in serum from experimental rats were determined by an enzyme-linked immunosorbent assay using S. mutans whole cells (WC) as the coating antigen. The specificities of salivary and serum immunoglobulin A (IgA) antibodies to particulate S. mutans antigens, lipoteichoic acid, S. mutans serotype g carbohydrate, and dextran were also determined. When 50 micrograms of ConA was used as the oral adjuvant with S. mutans 6715 WC immunogen, a slight enhancement of immune responses was obtained. A higher dose of ConA suppressed humoral responses to the immunogen. Enhanced immune responses, especially of the IgA isotype, in both serum and saliva were induced in gnotobiotic rats given MDP and either S. mutans 6715 WC or purified cell walls (CW) by gastric intubation. Elevated IgA antibody levels to CW, lipoteichoic acid, and carbohydrate were observed in rats given S. mutans WC and MDP by gastric intubation, whereas oral immunization with S. mutans CW and MDP resulted in higher antibody levels to CW and carbohydrate and lower levels to lipoteichoic acid when compared with the antibody levels in rats given antigen alone. Rats orally immunized with either S. mutans WC or CW and MDP and challenged with virulent S. mutans 6715 exhibited significantly (P less than or equal to 0.05) lower plaque scores, numbers of viable S. mutans in plaque, and caries scores than did rats immunized with antigen alone or in infected-only controls. In another series of experiments, a PG fraction derived from S. mutans 6715 CW was assessed for adjuvant properties. The oral administration of PG and either S. mutans WC or CW induced good salivary and serum IgA antibody responses. The specificity of the antibodies was similar to that obtained in rats given antigen and MDP. Rats receiving either S. mutans WC or CW and PG and challenged with virulent S. mutans 6715 had lower plaque scores, fewer numbers of viable S. mutans in plaque, and lower caries activity than did infected rats receiving S. mutans WC or CW immunogen alone. These results provide evidence that soluble adjuvants derived from the gram-positive bacterial CW, e.g., MDP and PG, are effective oral adjuvants and augment IgA immune responses to particulate S. mutans antigens which are protective against the mucosally associated disease, dental caries.

Adjuvants, Immunologic↗

PubMed1994

Evidence that L-(+)-lactate dehydrogenase deficiency is lethal in Streptococcus mutans.

In order to construct an effector strain for the replacement therapy of dental caries, we wished to combine the properties of low-level acid production and high-level colonization potential in a strain of Streptococcus mutans. To this end, we made a deletion in the lactate dehydrogenase (LDH) gene cloned from the bacteriocin-producing S. mutans strain JH1000. However, we were unable to substitute the mutant for the wild-type allele by transformation with linear DNA fragments. The mutated gene, carried on a suicide vector, was shown by Southern analysis to integrate into the JH1000 chromosome to yield transformants carrying both the wild-type gene and mutated LDH gene. Three spontaneous self-recombinants of one heterodiploid strain were isolated by screening 1,500 colonies for a loss of the tetracycline resistance encoded by the gene used to mark the LDH deletion. In all three cases, Southern analysis showed that a loss of tetracycline resistance was accompanied by a loss of the mutated LDH gene, resulting in restoration of the wild-type genotype. However, screening the same number of colonies for self-recombinants that did not make lactic acid during anaerobic growth in Todd-Hewitt broth failed to identify clones in which the wild-type allele was lost. A second, simpler screening of more than 80,000 colonies grown aerobically on glucose tetrazolium medium to identify low-level-acid-producing colonies was also unsuccessful. These results are interpreted as indicating that LDH deficiency is lethal in S. mutans under the cultivation conditions used in these experiments. The physiological bases for this hypothesis are described.

Blotting, Southern↗

PubMed1991

Inhibition of Streptococcus mutans adherence to hydroxyapatite with combinations of alkyl phosphates and nonionic surfactants.

Seven alkyl phosphate derivatives and three nonionic surfactants were examined for their ability to inhibit the adherence of 3H-labelled cells of Streptococcus mutans to hydroxyapatite (HA) treated with buffer (BHA) or parotid saliva (SHA). None of the compounds alone hindered binding of bacteria to BHA or SHA effectively. A combination of certain of the alkyl phosphates, notably a disodium phosphate of 1-octadecanol, and nonionic surfactant at a 1:1 molar ratio gave a strong inhibition of S. mutans adherence. Treatment of SHA with this combination resulted in 98% reduction of adherence. Adsorption of the two types of surface-active agents alone and in combinations was studied using 14C-labelled agents. Electrophoretic measurements revealed that surfaces treated with only alkyl phosphate became highly negatively charged, while surfaces treated with the combination had a zeta-potential of around zero. The results suggest that treatment with surfactants might be used to interfere with bacterial adherence on the tooth surface.

Bacterial Adhesion↗

PubMed1997

Role of the citrate pathway in glutamate biosynthesis by Streptococcus mutans.

In work previously reported (J. A. Gutierrez, P. J. Crowley, D. P. Brown, J. D. Hillman, P. Youngman, and A. S. Bleiweis, J. Bacteriol. 178:4166-4175, 1996), a Tn917 transposon-generated mutant of Streptococcus mutans JH1005 unable to synthesize glutamate anaerobically was isolated and the insertion point of the transposon was determined to be in the icd gene encoding isocitrate dehydrogenase (ICDH). The intact icd gene of S. mutans has now been isolated from an S. mutans genomic plasmid library by complementation of an icd mutation in Escherichia coli host strain EB106. Genetic analysis of the complementing plasmid pJG400 revealed an open reading frame (ORF) of 1,182 nucleotides which encoded an enzyme of 393 amino acids with a predicted molecular mass of 43 kDa. The nucleotide sequence contained regions of high (60 to 72%) homology with icd genes from three other bacterial species. Immediately 5' of the icd gene, we discovered an ORF of 1,119 nucleotides in length, designated citZ, encoding a homolog of known citrate synthase genes from other bacteria. This ORF encoded a predicted protein of 372 amino acids with a molecular mass of 43 kDa. Furthermore, plasmid pJG400 was also able to complement a citrate synthase (gltA) mutation of E. coli W620. The enzyme activities of both ICDH, found to be NAD+ dependent, and citrate synthase were measured in cell extracts of wild-type S. mutans and E. coli mutants harboring plasmid pJG400. The region 5' from the citZ gene also revealed a partial ORF encoding 264 carboxy-terminal amino acids of a putative aconitase gene. The genetic and biochemical evidence indicates that S. mutans possesses the enzymes required to convert acetyl coenzyme A and oxalacetate to alpha-ketoglutarate, which is necessary for the synthesis of glutamic acid. Indeed, S. mutans JH1005 was shown to assimilate ammonia as a sole source of nitrogen in minimal medium devoid of organic nitrogen sources.

Aconitate Hydratase↗

PubMedDate not supplied

Caries risk tests and salivary levels of immunoglobulins to Streptococcus mutans and Candida albicans in mouthbreathing syndrome patients.

The aim of this study was to compare microbiological and salivary variables possibly related to caries risk in treated and untreated mouthbreathing syndrome (MBS) children and control children. Thirty control children, 30 mouthbreathers and 25 treated mouthbreathers were studied for the numbers of lactobacilli, mutans streptococci and yeasts in their saliva. Snyder's test, salivary flow and buffering capacity were also evaluated. Levels of immunoglobulins to Candida albicans and Streptococcus mutans in the saliva were quantified using ELISA. Considering the results obtained for the microbiological and salivary caries risk tests, no significant differences were observed among the proportions of patients with small/negative and high/moderate caries risk in the studied groups. The level of IgG to S. mutans was significantly higher in the treated MBS group in relation to MBS patients. On the other hand, the median anti-S. mutans IgM level was lower in the treated MBS patients than in the other groups. For the studied anti-Candida immunoglobulins, IgM level was significantly lower in the treated MBS group than in the other groups. No differences were observed for anti-S. mutans and anti-Candida IgA levels among the groups. The findings suggest that mouthbreathing cannot be considered a risk factor for dental caries.

Analysis of Variance↗

PubMed1983

Immunologic cross-reactivity between Streptococcus mutans and mammalian tissues.

The presence of cross-reacting antigens shared by oral streptococci and human and monkey tissue was investigated by indirect immunofluorescence. Rabbit antisera prepared against two strains of each of the seven serotypes of Streptococcus mutans were incubated on sections of cardiac muscle, skeletal muscle, kidney, brain, liver, and skin. Antisera to S. mutans, serotype g, strain OMZ-65 reacted with cardiac muscle components. This reactivity could be reduced by absorption with bacterial cell membranes. Antisera to S. mutans serotype g, strain K-1 reacted with both cardiac and skeletal muscle but could not be reduced by absorption with bacterial cells, cell walls, or cell membranes. Antisera to S. mutans serotype g, strain OMZ-65 reacted with kidney glomeruli and could be completely absorbed by a cell wall preparation. S. mutans, serotype e, strain MT703 also reacted with kidney glomeruli but could not be reduced by absorption with bacterial antigens.

Brain↗