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PubMed1989

Screening of Taiwanese crude drugs for antibacterial activity against Streptococcus mutans.

Preliminary antibacterial screening of local crude drugs was carried out using the cariogenic bacterium, Streptococcus mutans. Of 79 aqueous extracts tested, 6 crude drugs were shown to have significant antibacterial activity with minimal inhibitory concentration equal to or lower than 7.8 mg/ml (expressed in terms of dry starting material). Of these effective crude drugs, Morus australis, Ludwigia octovalvis and Thuja orientalis were very effective in inhibiting the growth of serotypes c and d of S. mutans (MIC less than or equal to 2.0-7.8 mg/ml). Elephantopus scaber, Artemisia vulgaris, Mosla chinensis and Orthosiphon aristatus also exhibited considerable antibacterial activity (MIC = 7.8-23.4 mg/ml) against both serotypes. In the presence of 5% sucrose, the antibacterial potency of the majority of the extracts did not change for type c, while the potency decreased about one-half for type d.

Anti-Bacterial Agents↗

PubMed2003

The stress-responsive dgk gene from Streptococcus mutans encodes a putative undecaprenol kinase activity.

We analyzed a previously constructed stress-sensitive Streptococcus mutans mutant Tn-1 strain resulting from disruption by transposon Tn916 of a gene encoding a protein exhibiting amino acid sequence similarity to the Escherichia coli diacylglycerol kinase. It was confirmed that the mutation led to significantly reduced lipid kinase activity, while expression of the intact gene on a plasmid restored both kinase activity and the wild-type phenotype. Further analysis revealed that the product of the dgk gene in S. mutans predominantly recognizes a lipid substrate other than diacylglycerol, most likely undecaprenol, as demonstrated by its efficient phosphorylation and the resistance of the product of the reaction to saponification. The physiological role of the product of the dgk gene as a putative undecaprenol kinase was further supported by a significantly higher sensitivity of the mutant to bacitracin compared with that of the parental strain.

Bacterial Proteins↗

PubMed1979

Immunoglobulin A antibodies reactive with Streptococcus mutans in saliva of adults, children, and predentate infants.

Immunoglobulin A (IgA) antibodies reactive with Streptococcus mutans MT3 cells (serotype c) were sought, using an indirect enzyme-linked immunosorbent assay, in the saliva of humans who either harbored or did not harbor detectable levels of this organism. Samples of unstimulated whole saliva from three adults and one child who were infected with S. mutans contained IgA which bound to MT3 cells. Saliva samples of two adults studied also contained IgA which reacted with S. mutans strains of serotypes e, g, a, and b, the latter two of which are rarely isolated from humans. The saliva of three children who did not harbor detectable levels of S. mutans and of three of five predentate infants also contained IgA reactive with MT3 cells. The latter observation is of special interest since S. mutans does not colonize the mouth before eruption of teeth. Thus, the presence of salivary IgA reactive with S. mutans cells is not necessarily related to present or past infection by this organism. Absorption with MT3 cells markedly reduced the reactivity of adult saliva without greatly altering the total concentration of IgA present; this suggests that the IgA was not binding to S. mutans MT3 cells via Fc receptors. The possibility that the antibodies which reacted with S. mutans MT3 may have been induced to other bacteria with cross-reactive antigens was supported by the finding that absorption of saliva with mixed bacterial growth derived from common dairy products significantly reduced its reactivity. Absorption experiments further suggested that a significant portion of the salivary IgA antibodies was binding to glucans on the cell surface.

Adult↗

PubMed1980

Comparison of the glucosyltransferases of Streptococcus mutans gs-5 to a non-cariogenic mutant.

The extracellular glucosyltransferase (GTF) enzymes of Streptococcus mutans GS-5 and avirulent mutant GS-511 were fractionated using agarose and DEAE-cellulose columns. GTF of GS-5 produced both water-soluble and -insoluble glucans, while those of GS-511 made soluble products almost exclusively. Nearly all (98%) of the small amount of insoluble GTF enzyme made by GS-511 was bound to the cell wall.

Carbohydrates↗

PubMed1983

Effects of cell wall inhibitors on cell division in Streptococcus mutans.

The addition of inhibitors of cell wall biosynthesis to exponential-phase cultures of Streptococcus mutans may do one of three things, depending on the concentrations used: (i) prevent cell division at a time coincident with the onset of chromosome replication, (ii) prevent cell division later in the cell cycle coincident with or near completion of septation, or (iii) lead to limited cell lysis. The relative tolerance of S. mutans to inhibitors of cell wall biosynthesis may be due to the fact that S. mutans cultures treated with low levels of cell wall antibiotics seem to be blocked at a stage before initiation of autolytic activity, whereas cultures treated with high levels of these antibiotics seem to be blocked after termination of the autolytic phase. Thus, the cells escape the lytic death that is seen in other streptococci exposed to inhibitors of cell wall biosynthesis.

Anti-Bacterial Agents↗

PubMedDate not supplied

[Bacteriocins of Streptococcus mutans: mutacins].

A bioliographic survey about the production of a certain bactericidal substance (mutacins) by Streptococcus mutans has been done. The importance of bacteriocins of this micro-organism is due to its utility as a possible anti-caries agent performing as an influential factor in the colonization of the oral cavity, and also for serving for the typing of bacteria as an epidemiological "finger printing", determining the way of transmission of this micro-organism. Besides of stressing its clinical and epidemiological utility, we develop a review of other microbiological aspects.

Bacterial Typing Techniques↗

PubMed2006

A rapid and quantitative detection system for Streptococcus mutans in saliva using monoclonal antibodies.

A new semiquantitative enumeration system was developed to detect Streptococcus mutans in saliva. Using species-specific monoclonal antibodies, the system quickly detected salivary S. mutans in 30 min and classified the results into three levels. In this study, saliva samples collected from 28 young adults aged between 22 and 24 years were subjected to the monoclonal antibody-based detecting system and selective medium-based detecting methods. The results generated from the PCR-confirmed culture method indicated the mean salivary S. mutans counts at level 1, 2 and 3 were 5.7 x 10(4), 1.3 x 10(5) and 3.4 x 10(6) CFU/ml, respectively. The differences between level 3 and 1 and level 3 and 2 were statistically significant (one-way ANOVA; p < 0.01). The results generated from the system were consistent with the data generated from two culture-based commercial products.

Adult↗

PubMed1987

Serological typing of reference strains and clinical isolates of Streptococcus mutans by agglutination reactions and/or radioimmunoassay.

Rabbit antisera were prepared against eight different serotypes of Streptococcus mutans. After absorption with heterologous serotype strains the antisera were able to distinguish 21 reference strains of different serotypes of S. mutans by simple agglutination reactions and radioimmunoassay, both using intact whole cells. The reference serotypes a, b, d and g were differentiated by specific agglutination using the corresponding monospecific antiserum. Strains of serotypes c, e, f and h were discriminated by differential agglutination using anti-c, anti-e, anti-f or anti-h serum respectively, but the antisera cross-reacted slightly with other serotype strains. Using these antisera a total of 261 clinical isolates of S. mutans from human dental plaques were serotyped by agglutination reactions, in addition to which radioimmunoassay and the classical immunodiffusion tests in agar were also used in some cases. The results were quite consistent in the three methods. The predominant strain was of serotype c (187), followed by serotype f (28), g (10), d (5), e (4) and b (1). 26 strains were untypable and there were no serotype a or h strains.

Agglutination Tests↗

PubMed1996

The multiple-sugar metabolism (msm) gene cluster of Streptococcus mutans is transcribed as a single operon.

The multiple-sugar metabolism (msm) locus of Streptococcus mutans constitutes a non-PTS sugar uptake system responsible for the transport and utilization of raffinose, melibiose and isomaltotrioses. While previous studies have used polar mutations to suggest that these genes are co-transcribed, there has not been evidence to support this. In this report we present direct evidence that the msm genes can be transcribed as a single operon.

Base Sequence↗

PubMed1989

Construction and characterization of isogenic mutants of Streptococcus mutans deficient in major surface protein antigen P1 (I/II).

The gene (spaP) coding for the Streptococcus mutans major surface protein antigen P1 (or I/II) has been cloned into Escherichia coli (S. F. Lee, A. Progulske-Fox, and A. S. Bleiweis, Infect. Immun. 56:2114-2119, 1988). In the present study, this gene has been disrupted in vitro by insertional inactivation with pVA981, which carries a Tcr marker, and transformed into S. mutans NG8 (serotype c) by electroporation. Upon homologous recombination, the defective spaP was integrated into the genome as demonstrated by Southern hybridization analysis. One Tcr mutant, designated 834, selected by its nonreactivity with anti-P1 monoclonal antibodies, was found to lack the cell surface fuzzy layer which was clearly present on the parent cells. Analysis of extracellular fluids, sodium dodecyl sulfate-solubilized membranes, and cytoplasmic fractions by sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that 834 had protein profiles identical to the parent. However, a 185-kilodalton protein which reacts with anti-P1 antibodies was missing from the wall of 834, suggesting that spaP has been specifically inactivated. This mutant displayed levels of glucosyltransferase and fructosyltransferase activities similar to those of the parent. It was much less hydrophobic than the parent. S. mutans NG8 aggregated readily in the presence of clarified whole saliva or a high-molecular-weight salivary agglutinin. This strain also adhered to agglutinin-coated hydroxyapatite. The P1-negative mutants, however, did not display these two properties, suggesting that P1 may play a role in saliva-mediated aggregation and adherence.

Agglutination↗

PubMed1979

[Influence of culture media on the growth of Streptococcus mutans ATCC 25175 in the presence of various carbohydrates and their derivatives].

The growth of Streptococcus mutans ATCC 25 175 has been studied in the presence of various sugars (sorbitol, mannitol, lycasin, sorbose and xylitol) and compared to sucrose, glucose and fructose, added to a complex and a synthetic culture medium. In these two media, the decrease in pH was related to the bacterial growth; this fact was confirmed by the dosages of the liberated lactic acid. In the complex medium, the different sugars influenced only slightly the bacterial growth, whereas in the synthetic medium the micro-organisms did not grow in the presence of sorbose, xylitol or lycasin 80/55. An adaptation period was necessary before the beginning of bacterial growth in the synthetic medium supplemented with sorbitol and mannitol.

Carbohydrates↗

PubMed1980

Growth of Streptococcus mutans protoplasts is not inhibited by penicillin.

A method is described in which cells of Streptococcus mutans BHT can be converted to spherical, osmotically fragile protoplasts. Exponential-phase cells were suspended in a solution containing 0.5 M melezitose, and their cell walls were hydrolyzed with mutanolysin (M-1 enzyme). When the resultant protoplasts were incubated in a chemically defined growth medium containing 0.5 M NH4Cl, the protoplast suspensions increased in turbidity, protein, ribonucleic acid, and deoxyribonucleic acid in a balanced fashion. In the presence of benzylpenicillin (5 microgram/ml), balanced growth of protoplasts was indistinguishable from untreated controls. This absence of inhibition of protoplast growth in the presence of benzylpenicillin was apparently not due to inactivation of the antibiotic. When exponential-phase cells of S. mutans BHT were first exposed to 5 microgram of benzyl-penicillin per ml for 1 h and then converted to protoplasts, these protoplasts were also able to grow in chemically defined, osmotically stabilized medium. The ability of wall-free protoplasts to grow and to synthesize ribonucleic acid and protein in the presence of a relatively high concentration of benzylpenicillin contrasts with the previously reported rapid inhibition of ribonucleic acid and protein synthesis in intact streptococci. These data suggest that this secondary inhibition of ribonucleic acid and protein synthesis in whole cells is due to factors involved with the continued assembly of an intact, insoluble cell wall rather than with earlier stages of peptidoglycan synthesis.

Bacteriological Techniques↗

PubMed2006

Membrane composition changes and physiological adaptation by Streptococcus mutans signal recognition particle pathway mutants.

Previously, we presented evidence that the oral cariogenic species Streptococcus mutans remains viable but physiologically impaired and sensitive to environmental stress when genes encoding the minimal conserved bacterial signal recognition particle (SRP) elements are inactivated. Two-dimensional gel electrophoresis of isolated membrane fractions from strain UA159 and three mutants (Deltaffh, DeltascRNA, and DeltaftsY) grown at pH 7.0 or pH 5.0 allowed us to obtain insight into the adaptation process and the identities of potential SRP substrates. Mutant membrane preparations contained increased amounts of the chaperones DnaK and GroES and ClpP protease but decreased amounts of transcription- and translation-related proteins, the beta subunit of ATPase, HPr, and several metabolic and glycolytic enzymes. Therefore, the acid sensitivity of SRP mutants might be caused in part by diminished ATPase activity, as well as the absence of an efficient mechanism for supplying ATP quickly at the site of proton elimination. Decreased amounts of LuxS were also observed in all mutant membranes. To further define physiological changes that occur upon disruption of the SRP pathway, we studied global gene expression in S. mutans UA159 (parent strain) and AH333 (Deltaffh mutant) using microarray analysis. Transcriptome analysis revealed up-regulation of 81 genes, including genes encoding chaperones, proteases, cell envelope biosynthetic enzymes, and DNA repair and replication enzymes, and down-regulation of 35 genes, including genes concerned with competence, ribosomal proteins, and enzymes involved in amino acid and protein biosynthesis. Quantitative real-time reverse transcription-PCR analysis of eight selected genes confirmed the microarray data. Consistent with a demonstrated defect in competence and the suggested impairment of LuxS-dependent quorum sensing, biofilm formation was significantly decreased in each SRP mutant.

Adaptation, Physiological↗

PubMed2006

Population structure of plasmid-containing strains of Streptococcus mutans, a member of the human indigenous biota.

There are suggestions that the phylogeny of Streptococcus mutans, a member of the human indigenous biota that is transmitted mostly mother to child, might parallel the evolutionary history of its human host. The relatedness and phylogeny of plasmid-containing strains of S. mutans were examined based on chromosomal DNA fingerprints (CDF), a hypervariable region (HVR) of a 5.6-kb plasmid, the rRNA gene intergenic spacer region (IGSR), serotypes, and the genotypes of mutacin I and II. Plasmid-containing strains were studied because their genetic diversity was twice as great as that of plasmid-free strains. The CDF of S. mutans from unrelated human hosts were unique, except those from Caucasians, which were essentially identical. The evolutionary history of the IGSR, with or without the serotype and mutacin characters, clearly delineated an Asian clade. Also, a continuous association with mutacin II could be reconstructed through an evolutionary lineage with the IGSR, but not for serotype e. DNA sequences from the HVR of the plasmid produced a well-resolved phylogeny that differed from the chromosomal phylogeny, indicating that the horizontal transfer of the plasmid may have occurred multiple times. The plasmid phylogeny was more congruent with serotype e than with mutacin II evolution, suggesting a possible functional correlation. Thus, the history of this three-tiered relationship between human, bacterium, and plasmid supported both coevolution and independent evolution.

Biological Evolution↗

PubMed1980

Virulence-related physiological changes and antigenic variation in populations of Streptococcus mutans colonizing gnotobiotic rats.

The purpose of this study was to determine if populations of Streptococcus mutans which were undergoing antigenic variation while colonizing gnotobiotic rats concomitantly became altered in physiological characteristics which affected their virulence. S. mutans strain JBP (serotype c), which was freshly isolated from a carious lesion in a 6-year old child, was used to inoculate gnotobiotic rats; uninfected animals served as controls. Substrains were isolated from animals 1, 2, 3, 4, and 12 weeks after infection; samples of pilocarpine-stimulated saliva were also obtained from representative animals for antibody analyses. Isolates derived from stock cultures of strain JBP proved to be homogeneous with respect to all of the physiological characteristics monitored. However, substrains isolated from the animals within 4 weeks after infection were altered with respect to their ability to agglutinate in the presence of sucrose, their ability to form adherent growth in sucrose broth, and the terminal pH attained in glucose broth. Some isolates obtained 12 weeks after infection no longer synthesized detectable levels of c antigen or intracellular glycogen, and they formed atypical smooth colonies on mitis salivarius agar. With an enzyme-linked immunosorbent assay, low levels of immunoglobulin A (IgA) antibodies reactive with whole JBP cells were detected in saliva samples of uninfected control animals at each sampling period; these evidently were induced to antigens contained in the diet of the animals. Significantly higher levels of IgA antibodies were present in saliva samples from animals infected with strain JBP for 3 weeks or longer. Thus, the emergence of antigenic and physiological variants of S. mutans in the animals was paralleled by increased levels of salivary IgA antibodies. The reactivity of salivary IgG with JBP cells was low, and it fluctuated in both groups of animals. No antibodies of the IgM class were detected. When tested in gnotobiotic rats, several variants, including strains which no longer formed typical rough colonies or adherent growth in sucrose broth, proved much less virulent than parental strain JBP in inducing carious lesions. Prior oral immunization, which resulted in higher levels of salivary and serum IgA antibodies reactive with strain JBP, was found to accelerate the emergence of smooth-colony variants in the animals; it was also associated with decreased streptococcal population levels on the teeth and in feces of the rats. It is suggested that part of the mechanism by which artificial immunization leads to a reduction in dental caries development in experimental animals is due to the earlier selection of less virulent streptococcal populations.

Animals↗

PubMed1983

In vitro and in vivo complementation of Streptococcus mutans mutants defective in adherence.

Previous studies have shown that adherence-defective mutants of Streptococcus mutans PS14, serotype c, can be grouped into several different phenotypic groups. In this study a method was developed to test for complementation between pairs of nonadhering mutants which possess different genotypic defects. Mutant strains UAB95 and a spectinomycin-resistant derivative of UAB95 (UAB516) were found to exhibit increased levels of adherence when grown together with UAB230 in media containing sucrose as compared to the adherence of each strain grown separately. An increase in caries was also observed in gnotobiotic rats mixedly infected with the two mutants as compared to either strain alone. Tests revealed that UAB95 produced more water-insoluble glucan than its parent strain but had a defect in glucan binding. UAB230 was found to produce levels of a defective glucan that could not be bound by mutant or wild-type cells. Our results suggest that UAB95 produces a water-insoluble glucan which is bound by UAB230, thus allowing complementation for adherence and caries production.

Animals↗

PubMed1985

Infectivity and natural transmission of the bacterium Streptococcus mutans in monkeys (Macaca fascicularis) at different ages.

Oral inoculation of adolescent monkeys with laboratory strains of Streptococcus mutans resulted in only sporadic implantation. Oral colonization of all strains, except possibly one, was not enhanced by dietary sucrose compared with glucose nor by precleaning of accessible tooth surfaces. Infant animals were more susceptible to implantation by laboratory-maintained strains of Strep. mutans than adolescent or adult animals. This difference was magnified when in-vivo maintained Strep. mutans strains were used. Strep. mutans was readily acquired by uninfected adolescent animals from infected cage mates. Strep. mutans-free adolescent monkeys exhibited significant-salivary IgA and serum-IgG response to Strep. mutans antigen, possibly representing a cross-reaction to indigenous Streptococcus sanguis. Uninfected infant animals showed no salivary or serum response to Strep. mutans. There was no change in salivary IgA antibody to Strep. mutans in adolescent animals after implantation or in recipient animals after acquisition of Strep. mutans.

Age Factors↗

PubMed1981

The isolation of characterization of Streptococcus mutans serotype h from dental plaque of monkeys (Macaca fascicularis).

A new serotype (h) of Streptococcus mutans was isolated from the dental plaque of monkeys (Macaca fascicularis). Serotype h strains fermented mannitol and melibiose but not sorbitol or raffinose, failed to hydrolyse aesculin and arginine, did not produce hydrogen peroxide and were unable to grow in the presence of bacitracin at 2 units ml-1. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis of whole-cell proteins showed serotype h strains to be closely related to strains of genetic group III (i.e. serotypes d and g). The serotype-specific antigen of serotype h contained glucose and galactose but was antigenically distinct from the polysaccharide antigens of serotypes a, d and g. Serotype h strains preferentially colonized developmental grooves of teeth and the proportion of serotype h in the plaque flora was greater in monkeys fed a sucrose-rich diet than in monkeys fed a starch-based diet. A serotype h strain was cariogenic for germ-free rats fed a high-sucrose diet, and serotype h strains appear to be implicated in the caries process in monkeys.

Animals↗