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PubMed1977

Gingivitis, bacterial plaque, and Streptococcus mutans in naval recruits from Saudi Arabia.

Gingivitis, dental caries, bacterial plaque, and the prevalence of Streptococcus mutans in plaque were studied in a group of 52 naval recruits from Saudi Arabia at the Naval Training Center, Great Lakes, Illinois. Gingivitis and bacterial plaque were found at higher levels in Arabian navy men, compared to American navy men, but with similar relationships. The dental caries experience of the Arabians was low, and the prevalence of S. mutans in the bacterial plaque had no clear relationship to gingival inflammation.

Adolescent↗
PubMed1990

Primary reservoirs of Streptococcus mutans and their relationship to caries experience in adults with good oral hygiene.

Primary reservoirs of Streptococcus mutans were identified in a group of 21 adults with intact dentitions and good oral hygiene by obtaining multiple plaque samples from all available tooth surfaces. Routine cultural methods and a rapid plate scoring method employing a 7-point ordinal scale were used to assess S. mutans levels. Oral hygiene status (DI-S) and caries experience (DMFT and DMFS) were determined clinically. Primary S. mutans reservoirs (high scores) were restricted essentially to the posterior interproximal areas and occasionally in the occlusal pits and fissures of partially erupted mandibular third molars. An anterior to posterior gradient of increasing S. mutans scores was observed for interproximal sites. Oral hygiene scores correlated poorly with DMFT, DMFS and the S. mutans scores obtained for different anatomic locations.

Adult↗
PubMed1989

The influence of Streptococcus mutans on adhesion of Candida albicans to acrylic surfaces in vitro.

Adhesion of Candida albicans and Streptococcus mutans was studied by incubation of radiolabelled cells with acrylic test specimens in a chemically defined growth medium. Strep. mutans adhered firmly in the presence of sucrose, while C. albicans was only loosely attached to the acrylic in both glucose and sucrose media. Firm adhesion of C. albicans occurred when the yeast was incubated simultaneously with Strep. mutans, in the presence of sucrose. The adhesion of C. albicans was also stimulated by incubation with Strep. mutans culture supernatants. Adhesion was not affected by the presence of partially purified glucosyltransferase from Strep. mutans IB. Coaggregation between C. albicans and Strep. mutans upon growth in sucrose medium was observed by light and scanning electron microscopy. No coaggregation was observed in the presence of glucose.

Bacterial Adhesion↗
PubMed2001

The group I strain of Streptococcus mutans, UA140, produces both the lantibiotic mutacin I and a nonlantibiotic bacteriocin, mutacin IV.

Strains of Streptococcus mutans produce at least three mutacins, I, II, and III. Mutacin II is a member of subgroup AII in the lantibiotic family of bacteriocins, and mutacins I and III belong to subgroup AI in the lantibiotic family. In this report, we characterize two mutacins produced by UA140, a group I strain of S. mutans. One is identical to the lantibiotic mutacin I produced by strain CH43 (F. Qi et al., Appl. Environ. Microbiol. 66:3221-3229, 2000); the other is a nonlantibiotic bacteriocin, which we named mutacin IV. Mutacin IV belongs to the two-peptide, nonlantibiotic family of bacteriocins produced by gram-positive bacteria. Peptide A, encoded by gene nlmA, is 44 amino acids (aa) in size and has a molecular mass of 4,169 Da; peptide B, encoded by nlmB, is 49 aa in size and has a molecular mass of 4,826 Da. Both peptides derive from prepeptides with glycines at positions -2 and -1 relative to the processing site. Production of mutacins I and IV by UA140 appears to be regulated by different mechanisms under different physiological conditions. The significance of producing two mutacins by one strain under different conditions and the implication of this property in terms of the ecology of S. mutans in the oral cavity are discussed.

Actinomycetales↗
PubMed2004

Proteome analysis of Streptococcus mutans metabolic phenotype during acid tolerance.

Two-dimensional gel electrophoretic analysis of the proteome of Streptococcus mutans grown at a steady state in a glucose-limited anaerobic continuous culture revealed a number of proteins that were differentially expressed when the growth pH was lowered from pH 7.0 to pH 5.0. Changes in the expression of metabolic proteins were generally limited to three biochemical pathways: glycolysis, alternative acid production and branched-chain amino acid biosynthesis. The relative level of expression of protein spots representing all of the enzymes associated with the Embden-Meyerhof-Parnas pathway, and all but one of the enzymes involved in the major alternative acid fermentation pathways of S. mutans, was identified and measured. Proteome data, in conjunction with end-product and cell-yield analyses, were consistent with a phenotypic change that allowed S. mutans to proliferate at low pH by expending energy to extrude excess H(+) from the cell, while minimizing the detrimental effects that result from the uncoupling of carbon flux from catabolism and the consequent imbalance in NADH and pyruvate production. The changes in enzyme levels were consistent with a reduction in the formation of the strongest acid, formic acid, which was a consequence of the diversion of pyruvate to both lactate and branched-chain amino acid production when S. mutans was cultivated in an acidic environment.

Amino Acids, Branched-Chain↗
PubMed1980

Effect of growth conditions on sucrose phosphotransferase activity of Streptococcus mutans.

Sucrose and glucose phosphoenolpyruvate-dependent phosphotransferase (PTS) activities were studied in growing cultures of Streptococcus mutans serotype c and d/g cells adapted to either glucose or sucrose. Both acid production and optical absorbance were used to monitor growth in pH-controlled defined growth medium. The sucrose PTS activity appeared to be significant only under conditions of substrate limitation or slow growth as a result of low environmental pH. However, under environmental conditions which permitted rapid growth sucrose PTS activity appeared to be repressed, and only when the cells approached substrate-limited stationary phase after growth on high sucrose-supplemented medium was significant sucrose PTS activity again observed. A mutant apparently defective in sucrose PTS activity grew rapidly and produced acid under conditions of high environmental sucrose level but showed no sucrose PTS activity when the culture approached stationary phase. The mutant, however, after adaptation to glucose, demonstrated significant glucose PTS once the culture had attained the stationary growth phase. During diauxie growth in the presence of glucose and sucrose, there were sequential apparent inductions and repressions of glucose and sucrose PTS activities corresponding to decreases and increases of growth rate on the two substrates. Thus, S. mutans possesses at least two transport mechanisms for each substrate studied. One system (PTS) functions under conditions permitting slow growth and another functions under conditions permitting rapid growth.

Enzyme Induction↗
PubMed1998

The sgp gene modulates stress responses of Streptococcus mutans: utilization of an antisense RNA strategy to investigate essential gene functions.

The sgp gene from Streptococcus mutans has been previously isolated, characterized, and demonstrated to encode a G-protein. In order to investigate the function of this gene, a novel antisense RNA strategy was developed. Expression of sgp antisense RNA in Escherichia coli led to transient inhibition of growth. In addition, sgp antisense RNA expression in S. mutans resulted in decreased growth under environmental stress conditions (44 degrees C, acidic pH, and high osmolarity). Therefore, these results suggest that the sgp gene plays a role in modulating the stress responses of S. mutans. This approach could be applicable for investigating the function of essential genes in other organisms for which mutants are not available.

Bacterial Proteins↗
PubMed1984

Binding of Streptococcus mutans antigens to heart and kidney basement membranes.

Using indirect immunofluorescence, alkali-extracted components of Streptococcus mutans were found to bind in vitro to capillary walls and sarcolemmal sheaths of monkey cardiac muscle and to glomerular and tubular basement membranes of monkey kidney. Adsorption of S. mutans components to tissue fragments was also detected by indirect radioimmunoassay and immunoblotting on nitrocellulose paper. Antibodies did not bind to untreated, control tissues in these experiments, proving that antigens shared by S. mutans and tissue components were not involved. Rabbit and monkey heart and kidney components bound S. mutans antigens of 24,000, 35,000, and 65,000 Mr. Monkey heart also bound molecules of 90,000 and 120,000 Mr. Rabbits immunized by intravenous injection of disrupted S. mutans cells developed severe nephritis that was characterized by the deposition of immunoglobulins, complement component C3, and S. mutans antigens in the glomeruli. Immunoglobulin G eluted from nephritic kidneys reacted in immunoblots with the 24,000, 35,000, and 65,000 Mr components of S. mutans extract, indicating that the antigens that bound to tissue in vitro also bound in vivo and reacted with antibodies in situ. Antibodies to other S. mutans antigens were not detected in the kidney eluate, although they were present in the serum of the same rabbit.

Animals↗
PubMed1987

Streptococcus mutans in plaque from conventional and from non-gamma-2 amalgam restorations.

The frequency of Streptococcus mutans in plaque material from margins of conventional amalgam and non-gamma-2 amalgam fillings was examined in six subjects. One and 2 months after restorative treatment the mean values of the percentage S. mutans of the total number of microorganisms were somewhat lower in samples from non-gamma-2 amalgams than in those from conventional amalgams. The difference in values, however, was not statistically significant.

Adult↗
PubMed1996

Genetic and physiological analysis of the lethal effect of L-(+)-lactate dehydrogenase deficiency in Streptococcus mutans: complementation by alcohol dehydrogenase from Zymomonas mobilis.

CH4ts is a previously isolated recombinant mutant of Streptococcus mutans NG8 which produces a thermolabile L-(+)-lactate dehydrogenase (LDH) activity. It does not grow at 42 degrees C under a variety of cultivation conditions. In this study, we show that a batch culture of CH4ts shifted from 30 to 42 degrees C underwent rapid cessation of growth and accelerated cell death. The mutant grew at 42 degrees C in continuous culture under glucose-limiting conditions. Under these conditions, lactate production was replaced by production of ethanol and, to a smaller extent, acetoin. The cloned Zymomonas mobilis gene for alcohol dehydrogenase II, placed under the control of the S. mutans spaP regulatory signals, complemented LDH deficiency. The alcohol dehydrogenase-complemented mutant grew as well or better than NG8 on a variety of carbon sources at 42 degrees C and produced significant amounts of ethanol in place of lactic acid. These results are in accord with other approaches indicating that S. mutans has other enzymatic activities, including pyruvate formate-lyase and pyruvate dehydrogenase, for pyruvate metabolism. However, at high glucose concentrations, the levels of activity of these enzymes are apparently insufficient to compensate for the absence of LDH.

Alcohol Dehydrogenase↗
PubMed1980

Partial purification and properties of a mannofructokinase from Streptococcus mutans SL-1.

Fructokinase activity was demonstrated in seven strains of oral streptococci. The enzyme purified from Streptococcus mutans SL-1 was capable of phosphorylating both D-fructose and D-mmannose to their respective 6-phosphates. Phosphorylation of both fructose and mannose was dependent on adenosine 5'-triphosphate and a divalent metal ion. The molecular weight of the purified enzyme was estimated to be 49,000. The apparent Km of the enzyme for fructose was 0.63 mM. This enzyme also utilized mannose as a substrate, with an apparent Km for mannose of 0.37 mM. Since the activities of the enzyme toward mannose and fructose were not separated upon purification of the enzyme and since mannose was a competitive inhibitor of fructose phosphorylation, the purified kinase is a single enzyme, mannofructokinase, with dual specificity for both mannose and fructose. A role for this enzyme in carbohydrate metabolism in S. mutans is postulated.

Adenosine Triphosphate↗
PubMed2005

Influence of sample type and collection method on Streptococcus mutans and Lactobacillus spp. counts in the oral cavity.

OBJECTIVES: This study compared three methods of Streptococcus mutans and Lactobacillus spp. detection in the oral cavity: saliva swab (SS)-sample of stimulated saliva collected with swab; whole saliva (WS)-sample of 2 ml of stimulated saliva; and the dental plaque method (DP)-plaque sample of all dental surfaces. METHODS: Thirty children were included in this study. In the first 15 children, the SS and WS methods were carried out before the dental plaque collection, and in the following 15, the sequence was inverted to evaluate possible interference of the methods sequence. The samples were diluted and inoculated in SB20 and Rogosa agar, respectively for S.mutans and Lactobacillus spp., at 37 degrees C for 48 h. RESULTS: The results (cfu/mL) of S. mutans were analysed by the statistical Friedman's test. The levels of Lactobacillus spp. were analysed by descriptive statistics due to the high proportion of zero counts in the culture. In the first sequence of methods, the number of S. mutans counted for the SS method was inferior to DP and WS (P<0.05), and the results for the WS and DP methods were similar. The detection of Lactobacillus spp. was observed just by the WS (100%) and SS (14.3%) methods. However, in the second experimental set the number of S. mutans detected by the DP method was similar to those of the SS and WS, however, the WS method showed higher values than SS (P<0.05). A greater number of Lactobacillus spp. was detected by the WS method (100%), followed by SS (55.5%) and DP (33.3%). CONCLUSIONS: The dental plaque collection and the sample of stimulated whole saliva presented similar results in the S. mutans count. The most suitable method to detect the Lactobacillus spp. level in the oral cavity is the stimulated whole saliva method.

Child↗
PubMed2004

Streptococcus mutans strains harboring collagen-binding adhesin.

A previously unidentified 120-kDa protein was detected in Streptococcus mutans strain Z1 and was involved in the cold-agglutination of the strain. We have identified the gene, designated cnm, as being involved in the agglutination of strain Z1 following random mutagenesis. The amino acid sequence of the deduced Cnm protein exhibited high similarity to those of collagen-binding adhesins from staphylococci and other organisms. To confirm whether the protein is involved in collagen-binding, we cloned a cnm gene fragment, overexpressed it in E.coli, and prepared crude extracts. The extracts containing recombinant protein exhibited binding to immobilized collagen and laminin but not to fibronectin. Compared with the parental strain Z1, the cold-agglutination-negative mutant 05A02 exhibited reduced binding to collagen and laminin but retained that to fibronectin. This gene was detected in some strains of S. mutans. Therefore, the cnm gene encoded a new strain-specific member of the collagen-binding adhesin family.

Adhesins, Bacterial↗
PubMed1983

Effective immunity to dental caries: gastric intubation of Streptococcus mutans whole cells or cell walls induces protective immunity in gnotobiotic rats.

Gnotobiotic rats were given Streptococcus mutans 6715 whole cells (WC), purified cell walls (CW), or cell wall lysate by gastric intubation (GI), and assessments were made of humoral immune responses in serum and saliva and of caries protection. Levels of secretory immunoglobulin A (IgA) and IgG antibodies to S. mutans WC in saliva samples from experimental rats were determined by an enzyme-linked immunosorbent assay. Serum antibody levels of the IgM, IgG, and IgA isotypes were also determined. Similar levels of salivary antibodies were induced in rats given S. mutans WC or CW by GI, whereas lower salivary antibody titers were observed in rats given cell wall lysate by the oral route. The level of serum antibodies in the various groups of rats also reflected the oral antigen used. The specificity of salivary IgA and serum IgG antibodies in the various groups of rats was determined by enzyme-linked immunosorbent assay with lipoteichoic acid, serotype g carbohydrate, dextran, CW, and WC as coating antigens. Salivary IgA and serum IgG antibodies in rats given S. mutans WC or CW by GI were primarily directed to lipoteichoic acid and serotype g carbohydrate. The presence of salivary IgA antibodies to S. mutans in rats given either S. mutans WC or CW by GI correlated with a significant reduction in the levels of plaque, numbers of viable S. mutans in plaque, and caries scores when compared with the control animals (infected only). These results demonstrate that particulate antigens of S. mutans induce salivary immune responses when given by GI to gnotobiotic rats and that the presence of these antibodies correlates with caries protection.

Animals↗
PubMed2000

Tn917-lac mutagenesis of Streptococcus mutans to identify environmentally regulated genes.

Previously, we demonstrated successful Tn917 mutagenesis of the oral pathogen Streptococcus mutans using pTV1-OK (Km(r), repATs), a temperature conditional replicative delivery vector carrying a lactococcal pWVO1Ts backbone. In this report we describe the construction and utilization of pTV32-OK, a plasmid harboring Tn917-lac (em(r), beta-gal(+)) that was employed to isolate transcriptional fusions of the Escherichia coli lacZ reporter gene with streptococcal promoters in S. mutans strain NG8. Tn917-lac transposition occurred at a frequency of ca. 10(-6) with 20% of the resultant em(r) clones displaying varying levels of lacZ expression. Tn917-lac mutants that expressed beta-galactosidase activity under growth conditions of glucose limitation, acidic pH, 35 mM NaCl, and elevated (42 degrees C) temperature were isolated. Further characterization of one of the mutants with increased beta-gal activity under glucose limitation, strain AS42, revealed maximal activity in batch culture in stationary phase after glucose depletion. The beta-gal activity of AS42 also was found to be repressed 3-fold in medium containing 2% glucose relative to measured activity from cells suspended in the same medium containing no glucose. Further phenotypic analysis revealed that AS42 had a 30% lower growth yield than the parent strain NG8 when grown in pH 5 medium. Sequence analysis of the region harboring the transposon revealed that the lacZ fusion occurred near the 3'-end of a gene encoding a homolog of an ATP binding protein from a family of Gram-positive ABC transporters. These findings demonstrate that Tn917-lac mutagenesis can be used to identify environmentally regulated genes in S. mutans and possibly in other medically relevant streptococcal species.

Amino Acid Sequence↗
PubMed1992

Effect of different glass ionomers on the acid production and electrolyte metabolism of Streptococcus mutans Ingbritt.

In order to study the effects of different glass ionomers on the metabolism of Streptococcus mutans, test slabs of freshly mixed conventional glass ionomer (Fuji), silver glass ionomer (Ketac-Silver), composite (Silux), and 2-week-old Fuji were fitted into the bottom of a test tube. A plaque-like layer of S. mutans strain Ingbritt was centrifuged onto the test slabs, and the samples were incubated for 20 h in 1.7% (w/v) sucrose solution. For freshly mixed Fuji and Ketac-Silver, the pH fall was significantly smaller than for old Fuji and composite. These materials also released the largest amount of fluoride into the fluid phase. Incubation with glass ionomer materials led to an increase in the cellular concentration of fluoride in bacteria, but intracellular fluoride did not correlate with the fall in pH. The lowest pH was associated with the lowest cellular magnesium content. Ketac-Silver released large amounts of calcium in the fluid phase, and the cellular calcium content was doubled in this group. The results show that freshly mixed glass ionomers affect acid production and electrolyte metabolism of S. mutans in vitro. The effect of conventional glass ionomer, however, seems to disappear after a few weeks. The effects of calcium and silver released by cermet glass ionomer deserve further study.

Acids↗