SEARCH · PubMed Health

Results for “Streptococcus sobrinus”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 757 records · Page 42Linked to original sources

PubMed2000

Nucleotide sequencing and transcriptional analysis of two tandem genes encoding glucosyltransferase (water-soluble-glucan synthetase) in Streptococcus cricetus HS-6.

Two tandem genes encoding glucosyltransferase synthesizing water-soluble glucan (GTF-S) were cloned from the lambda gene library of Streptococcus cricetus HS-6 (serotype a) using anti-GTF-S antibody, and the nucleotide sequences were analyzed. The two genes (ORF1 and ORF2) were identified as streptococcal glucosyltransferases based on the following evidence: [1] the deduced amino acid sequences of their products have an active site for catalytic action and C-terminal repeated units for dextran binding, and [2] a homology search revealed that the ORF1 and ORF2 products are homologous to the GtfS protein (77.4%) of S. downei Mfe28 and GtfT protein (83.8%) of S. sobrinus OMZ176, respectively, which are both known to have GTF-S activity. Therefore, ORF1 and ORF2 might be designated gtfS and gtfT of S. cricetus, respectively. A Northern blotting and RNase protection assay suggested that the gtfS and gtfT of S. cricetus are transcribed as a single bicistronic mRNA as well as separate monocistronic mRNAs. Primer extension analysis indicated multiple transcriptional start points for each gene.

Amino Acid Sequence↗

PubMed1990

Identification of mutans streptococci with monoclonal antibodies.

Mutans streptococci have been correlated with dental caries. The identification of the species within this group is still a problem. The characterization of a monoclonal antibody (Mab) OMVU10 against S. sobrinus as well as the isolation and characterization of Mabs against S. mutans (OMVU30 and OMVU31), S. cricetus (OMVU40) and mutans streptococci (OMVU2) is described. The epitope specificity for OMVU10 and OMVU31 was cell-wall antigen B in both cases although both Mabs recognized different species-specific epitopes. OMVU40 was cross reactive with Streptococcus sanguis taxon 3. All other Mabs were specific for one species. Using these Mabs, a key to the identification of mutans streptococci is developed. This key was tested for 85 wild type isolates of mutans streptococci and proved to be highly reliable and easy to perform.

Antibodies, Monoclonal↗

PubMed2006

Identification and molecular characterization of an N-Acetylmuraminidase, Aml, involved in Streptococcus mutans cell separation.

We previously demonstrated Streptococcus mutans produces two bacteriolytic enzymes of 100 kDa and 80 kDa (G. Yoshimura et al. Microbiol. Immunol. 48, 465-469, 2004). Here, we identified the protein sequence of these enzymes and found they come from a single gene product designated as automutanolysin (Aml). Aml has a modular design where the N-terminus contains five 13-amino-acid repeats and a C-terminal enzyme active domain. Aml selectively lyses S. mutans and S. sobrinus but no other oral streptococci. This suggests Aml possesses strong substrate specificity towards cariogenic bacteria present in the human oral cavity. Analysis of S. mutans peptidoglycan fragments released by Aml shows the enzyme is an N-acetylmuraminidase. We found Ca(2+) enhances the activity; and EGTA, EDTA and iodoacetic acid inhibit the activity. The optimum pH range for lytic activity was 6 to 7. Disruption of the aml gene in S. mutans results in the formation of a longer bacterial cell chain length that was dispersed by the addition of a low concentration of Aml. This suggests Aml is involved in S. mutans cell separation.

Amino Acid Sequence↗

PubMed1990

Cloning and inactivation of the gene responsible for a major surface antigen on Streptococcus mutans.

To understand more fully the biological function(s) and investigate the reported cross-reactivity with heart tissue of antigen P1 (I/II) of Streptococcus mutans (serotype c), this molecular biological study of the responsible gene, spaP, was undertaken. A 5.2 kb Hin dIII fragment of strain NG5 was cloned into Escherichia coli JM109 by a shotgun procedure with pUC18 as the vector. Recombinant SM2949 expressed a P1 fusion protein under the control of the streptococcal promoter. Southern analysis revealed hybridization of pSM2949 with DNA from Strep. mutans (serotypes c, e, f), Strep. cricetus (a) and Strep. sobrinus (d), but not Strep. sobrinus (g), Strep. rattus (b) or Strep. downei (h). Recombinant (r) antigen was detected in E. coli periplasm, indicating the presence of a signal sequence. This product (of Mr 155K) showed partial identity to the native streptococcal P1 antigen by Ouchterlony double-diffusion analysis. The N-terminal 28 amino acid residues of rP1 were determined by Edman degradation analysis and an end-labelled oligonucleotide probe corresponding to residues 8-13 was used to determine the 5'-3' orientation of spaP by Southern hybridization with restriction enzyme digests of pSM2949. Rabbit antisera made against native and rP1 did not cross-react with human heart tissue. Isogenic mutants of strain NG8 were isolated after transformation with insertionally inactivated spaP. Each mutant was non-reactive with anti-P1 antisera. Selected mutants were shown to have a defective spaP gene incorporated into their chromosomal DNA.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗

PubMed1990

Low-cariogenicity of the tetrasaccharide nystose.

1. The effect of nystose on cariogenic factors of mutans streptococci was investigated. 2. Nystose was not utilized as a substrate for the growth, lactic acid production, plaque formation and cellular aggregation of serotype a-g strains of mutans streptococci. 3. Furthermore, nystose did not served as a substrate for water-insoluble glucan formation by glucosyltransferase (GTase) from strains used. 4. In the cellular adherence experiment using nystose, the amount of serotype d cells that adhered to glass surface was almost zero. 5. In the presence of sucrose, nystose inhibited GTase activity and adherence of cells. 6. Finally, significantly lower caries score was observed in rats infected with Strep. sobrinus and fed with diet containing nystose as compared with sucrose.

Animals↗

PubMed1990

Isolation and some properties of extracellular glucan-producing strains of human oral Streptococcus salivarius.

A total of eighteen strains of Streptococcus salivarius, which formed rough gelatinous, rough mucoid or smooth mucoid colonies on sucrose agar media, were isolated from the saliva and tongue dorsum of adults. All of the isolates produced glucans as well as fructans from sucrose. The bulk of the glucans was synthesized by the extracellular enzyme fraction and was water insoluble, whereas most of the fructans were synthesized by the cell-associated enzyme fraction and were water soluble. All strains formed microbial deposits on wire and glass surfaces when cultured in sucrose broth, but their sucrose-dependent adhesion was apparently looser than that produced by a cariogenic S. sobrinus strain. The rough gelatinous colony forming strains possessed a greater ability to synthesize water-insoluble glucans and produced heavier deposits with higher cohesion. Preliminary studies showed that the S. salivarius of such characteristic forms of colony were detected primarily in the saliva and tongue dorsum: the smooth mucoid colony formers appeared to predominate in the tongue coat and the rough mucoid and rough gelatinous colony formers were prominent in saliva. Isolation of these S. salivarius from dental plaques was low.

Adult↗

PubMed1991

Dental caries and salivary and microbial conditions in 50-60-year-old persons.

In a group of 124 persons, 50-60 yr old, the prevalence at baseline of mutans streptococci (MS) and lactobacilli and the salivary secretion rate and buffer capacity were examined. The mean secretion rate was 1.58 mL/min with a flow rate below 1 mL/min found in 20% of the persons. A buffer capacity below end pH 5.5 was observed in 64% of the subjects. MS was not detected in 5% of the persons whereas 17% had 10(6) or more MS per ml saliva. Lactobacilli were not found in 10% of the persons while 21% had counts in excess of 10(5) CFU mL. A new examination 5 yr later in 1986 revealed no significant changes in secretion rate and buffer capacity or in the population of lactobacilli, whereas markedly elevated levels of salivary MS were found. S. sobrinus was detected in 35-37% of the persons at the two examinations. Persons with both S. mutans and S. sobrinus had more MS than persons with only S. mutans.

Buffers↗

PubMed2002

Effects of compounds found in propolis on Streptococcus mutans growth and on glucosyltransferase activity.

Propolis, a resinous bee product, has been shown to inhibit the growth of oral microorganisms and the activity of bacterium-derived glucosyltransferases (GTFs). Several compounds, mainly polyphenolics, have been identified in this natural product. The present study evaluated the effects of distinct chemical groups found in propolis on the activity of GTF enzymes in solution and on the surface of saliva-coated hydroxyapatite (sHA) beads. Thirty compounds, including flavonoids, cinnamic acid derivatives, and terpenoids, were tested for the ability to inhibit GTFs B, C, and D from Streptococcus mutans and GTF from S. sanguinis (GTF Ss). Flavones and flavonols were potent inhibitors of GTF activity in solution; lesser effects were noted on insolubilized enzymes. Apigenin, a 4',5,7-trihydroxyflavone, was the most effective inhibitor of GTFs, both in solution (90.5 to 95% inhibition at a concentration of 135 microg/ml) and on the surface of sHA beads (30 to 60% at 135 microg/ml). Antibacterial activity was determined by using MICs, minimum bactericidal concentrations (MBCs), and time-kill studies. Flavanones and some dihydroflavonols, as well as the sesquiterpene tt-farnesol, inhibited the growth of S. mutans and S. sobrinus; tt-farnesol was the most effective antibacterial compound (MICs of 14 to 28 microg/ml and MBCs of 56 to 112 microg/ml). tt-Farnesol (56 to 112 microg/ml) produced a 3-log-fold reduction in the bacterial population after 4 h of incubation. Cinnamic acid derivatives had negligible biological activities. Several of the compounds identified in propolis inhibit GTF activities and bacterial growth. Apigenin is a novel and potent inhibitor of GTF activity, and tt-farnesol was found to be an effective antibacterial agent.

Animals↗

PubMed1996

Direct detection of Streptococcus mutans in human dental plaque by polymerase chain reaction.

Streptococcus mutans is an etiological agent in human dental caries. A method for the detection of S. mutans directly from human dental plaque by polymerase chain reaction has been developed. Oligonucleotide primers specific for a portion of the dextranase gene (dexA) of S. mutans Ingbritt (serotype c) were designed to amplify a 1272-bp DNA fragment by polymerase chain reaction. The present method specifically detected S. mutans (serotypes c, e and f), but none of the other mutans streptococci: S. cricetus (serotype a), S. rattus (serotype b), S. sobrinus (serotypes d and g), and S. downei (serotype h), other gram-positive bacteria (16 strains of 12 species of cocci and 18 strains of 12 species of bacilli) nor gram-negative bacteria (1 strain of 1 species of cocci and 20 strains of 18 species of bacilli). The method was capable of detecting 1 pg of the chromosomal DNA purified from S. mutans Ingbritt and as few as 12 colony-forming units of S. mutans cells. The S. mutans cells in human dental plaque were also directly detected. Seventy clinical isolates of S. mutans isolated from the dental plaque of 8 patients were all positive by the polymerase chain reaction. These results suggest that the dexA polymerase chain reaction is suitable for the specific detection and identification of S. mutans.

Animals↗

PubMed1993

Sequence of the gtfK gene of Streptococcus salivarius ATCC 25975 and evolution of the gtf genes of oral streptococci.

Many strains of oral streptococci secrete glucosyltransferases (GTFs) that polymerize sucrose into glucans that form an integral part of the plaque matrix on the tooth surface. Recently, we reported the cloning of two closely linked GTF-encoding genes (gtfJ and gtfK) from Streptococcus salivarius ATCC 25975 as well as the sequence of gtfJ, which encodes a primer-dependent GTF that synthesizes an insoluble product (a GTF-I). In this communication we report the sequence of gtfK, which encodes a primer-dependent GTF that synthesizes a soluble product (a GTF-S), as well as the sequence of a small downstream open reading frame of unknown function. The deduced sequence of GtfK was compared with those of seven other streptococcal Gtfs and an unrooted phylogenetic tree constructed. This analysis suggested that Gtfs with similar product specificities do not form phylogenetic clusters and was consistent with currently accepted phylogenetic schemes. The tree was tested by constructing a series of 'sub-trees' from different blocks of the alignment. Evidence was obtained for recombination events involving gtfB and gtfC from S. mutans GS-5, gtfJ and gtfK from S. salivarius, as well as the gtfI genes from S. downei and S. sobrinus. The recombination events between gtfB and gtfC, and between the two gtfI genes, were confirmed by examining divergences at silent sites.

Algorithms↗

PubMed1999

Functional and immunogenic characterization of two cloned regions of Streptococcus mutans glucosyltransferase I.

Glucosyltransferase (GTF) enzymes of mutans streptococci are considered virulence factors due to their ability to synthesize adhesive glucans, which facilitate cell-to-cell adherence and accumulation. In this study we report the cloning, expression, and characterization of the catalytic (CAT) and glucan-binding (GLU) domains of S. mutans GTF-I encoded by gtfB. The CAT and GLU polypeptides represent amino acid residues 253 to 628 and 1183 to 1473, respectively, of S. mutans GTF-I. Antibodies to recombinant CAT and GLU were generated in rabbits and purified by affinity chromatography. Purified anti-CAT antibodies significantly inhibited water-insoluble glucan synthesis by S. mutans and S. sobrinus GTFs (P < 0.0001 and P < 0.05, respectively). The purified anti-GLU antibodies significantly inhibited both water-insoluble and water-soluble glucan synthesis by S. mutans GTFs (P < 0.0001 and P < 0.05, respectively). These results demonstrate that anti-CAT and anti-GLU antibodies are capable of inhibiting a variety of GTF activities. Since antibodies to S. mutans in saliva are implicated in protection against disease, we next assessed the ability of CAT and GLU polypeptides to induce mucosal antibody responses in mice. Intranasal (i.n.) immunization of mice with CAT showed significantly (P < 0.005) elevated levels of specific immunoglobulin G (IgG) antibody activity in serum and specific IgA antibody activity in serum, saliva, vaginal washes, and fecal samples. GLU immunized animals showed significantly (P < 0.005) elevated levels of specific IgA antibody activity in serum and vaginal secretions. Taken together, these results demonstrate that the recombinant CAT and GLU polypeptides are effective in inducing both mucosal and systemic immune responses. The ability of these polypeptides to induce a mucosal IgA immune response in mice after i.n. immunization supports their use as subunit vaccine candidates in the development of an anticaries vaccine.

Animals↗

PubMed1987

Isolation and characterization of monoclonal antibodies specific for antigen P1, a major surface protein of mutans streptococci.

A panel of 15 murine monoclonal antibodies (MAbs; 14 immunoglobulin G1, 1 immunoglobulin G2a) directed against antigen P1, a major surface protein of mutans streptococci, was prepared. All of these MAbs reacted by the enzyme-linked immunosorbent assay with solubilized wall material from Streptococcus mutans Ingbritt 175 (a serotype c strain which retains significant amounts of P1 in its cell wall), culture supernatant fluid from Ingbritt 162 (a strain which excretes large amounts of P1 into the culture medium), and purified P1. By Western immunoblotting, these MAbs were observed to react with a high-molecular-weight polypeptide which comigrated with antigen P1. None of these MAbs cross-reacted with human heart tissue or with various eucaryotic proteins. When whole cells of various strains of mutans streptococci were screened against the panel of MAbs, the strongest reactivities were noted with strains of serotype c and e S. mutans, while a serotype f strain of S. mutans, along with S. sobrinus and S. cricetus strains, reacted somewhat more weakly. S. rattus strains were completely negative. Results obtained with bacterial culture supernatants were qualitatively similar. The surface localization of antigen P1 was confirmed by electron microscopy with an indirect immunogold technique. In sectioned S. mutans cells, labeling appeared to be associated with a fibrillar "fuzzy coat" layer, which was far more prominent on cells of Ingbritt 175 than on those of Ingbritt 162.

Animals↗

PubMed1990

[Anti-caries effects of polyphenol compound from Camellia sinensis].

Polyphenol compound (designated Sunphenon) from leaf of Camellia sinensis have been partially purified by extraction of the boiling water with ethyl acetate. The effect of Sunphenon on cariogenic Streptococcus mutans groups (serotype c and g) was studied in both in vitro and in vivo. The summary of results were described as follows; 1) Addition of Sunphenon to S. mutans JC-2 (c) caused a decrease in cell viability. The activity of Sunphenon showed that multiple application are required for killing and maximum effect was seen between 60 and 90 min treatment. However, treatment of S. mutans with Sunphenon did not induce complete cell death after 90 min incubation. 2) When S. mutans JC-2 (c) was pretreated with Sunphenon, the cellular attachment on saliva-treated hydroxyapatite surface was significantly reduced. 3) When saliva-treated hydroxyapatite surface was pretreated with Sunphenon, the cellular attachment of S. mutans JC-2 (c) was also markedly inhibited. 4) Sunphenon had no inhibitory effect on lactic acid production by S. mutans JC-2 (c). 5) Sunphenon showed a strong inhibitory effect against water-insoluble glucan synthesis by glucosyltransferase from S. mutans JC-2 (c) or S. sobrinus 6715 (g). 6) specific pathogen-free rats infected with S. mutans JC-2 (c) and fed a cariogenic diet containing 0.5%. Sunphenon developed significantly fewer carious lesions than controls infected with S. mutans and fed the same diet without Sunphenon. Furthermore, feeding of the drinking water containing 0.1% Sunphenon reduced caries incident in S. mutans in infected animals.

Animals↗

PubMed1988

Cloning and expression of a Streptococcus sanguis surface antigen that interacts with a human salivary agglutinin.

Human saliva contains a high-molecular-weight glycoprotein (agglutinin) which binds to specific streptococci in a calcium-dependent reaction leading to the formation of bacterial aggregates. We report the cloning of a gene encoding a surface antigen from Streptococcus sanguis M5 and show that the expressed protein inhibits agglutinin-mediated aggregation and specifically binds the salivary agglutinin in a calcium-dependent fashion. Clones isolated from the immunological screening of S. sanguis M5 genomic libraries with polyclonal antibodies against whole cells were assayed for the ability to compete with S. sanguis for agglutinin. One clone, pSSP-5, expressed antigens of 165 and 130 kilodaltons (kDa) possessing this activity. A 3-kilobase-pair (kbp) insert fragment from this clone was used to screen a genomic library in lambda EMBL3 which resulted in the isolation of clone SSP-5A. This clone contained an insert of 17 kb and expressed proteins of 170 to 205 kDa that reacted with the anti-S. sanguis antibodies. Subcloning of a 5.3-kbp EcoRI-BamHI fragment from SSP-5A produced pEB-5, which expressed streptococcal components that were indistinguishable from SSP-5A. The streptococcal antigen was purified by gel permeation and ion exchange chromatography and shown to potently compete with S. sanguis M5 cells for agglutinin. The antigen also bound purified salivary agglutinin in the presence of 1 mM CaCl2. This binding was inhibited by EDTA. Both the SSP-5 antigen and a 205-kDa protein in surface protein extracts from S. sanguis M5 cross-reacted with antibodies directed against antigen B from S. mutans and SpaA from S. sobrinus 6715. These results indicate that a 205-kDa surface protein that is antigenically related to SpaA and antigen B is involved in the binding of salivary agglutinin to S. sanguis M5.

Agglutinins↗

PubMed1989

[Non-cariogenicity of maltitol in vitro and animal experiments].

The caries inducing activity of maltitol was examined in in vitro and animal experiments. Fifteen strains of oral streptococci were not able to ferment maltitol. Also, maltitol inhibited the glucan synthesis from sucrose by GTases from mutans streptococci. However, the inhibition of growing-cell adherence was not so marked with the addition of maltitol to sucrose culture. In the animal experiments, maltitol did not induced dental caries in rats infected with mutans streptococci. Furthermore, maltitol significantly inhibited the sucrose-induced dental caries in rats infected with S. sobrinus 6715. However, there was no significant difference in rats infected with S. mutans MT8148R. These results indicated that maltitol is useful as a non-cariogenic sucrose substitute.

Animals↗

PubMed1989

Specificity of monoclonal antibodies in local passive immunization against Streptococcus mutans.

Local oral passive immunization in human subjects with a monoclonal antibody (MoAb) raised against the 185-kD antigen I/II from S. mutans significantly reduced or prevented oral colonization of an exogenous strain of the organism. In subjects sham-immunized with either saline or an unrelated MoAb, however, significantly greater proportions of S. mutans persisted for a longer duration than in those immunized with the specific anti-streptococcal MoAb. Recolonization of indigenous S. mutans after this organism was reduced to undetectable levels by an antimicrobial agent has also been completely prevented with specific MoAb. Indeed, S. mutans was not detected for a period of over 1 year, as compared with recolonization within 10-82 days in the control subjects. The specificity of MoAb in preventing colonization of the streptococci was studied with four MoAb. This revealed that: (1) the sub-class of antibody is not an essential factor, as both MoAb Guy's 1 and 13 prevented colonization, although Guy's 1 is an IgG2a and Guy's 13 is an IgG1 class of antibody; (2) serotype specificity is important, as MoAb Guy's 9, which only recognizes S. sobrinus (serotypes d and g), does not prevent colonisation by S. mutans (serotype c); (3) neither protein nor carbohydrate nature of the putative adhesin was a determining factor, because MoAb Guy's 1 recognizes a carbohydrate and Guy's 13 a protein determinant and both MoAb prevented adherence of S. mutans; and (4) epitope specificity appears to be the most important factor in preventing adherence of S. mutans, as MoAb Guy's 11 and 13 share the same serotype specificity and both recognize a protein determinant, yet only Guy's 13 prevents colonisation. The long duration of protection from re-colonization by indigenous S. mutans, lasting about 1 year after application of the specific MoAb was stopped, cannot be accounted for by functional MoAb remaining on the teeth. We suggest that initially the MoAb prevents colonization by S. mutans and that the ecological niche vacated by this streptococcus is filled by other organisms from the oral flora, thereby discouraging re-colonization by S. mutans.

Adult↗

PubMed2004

Identification of another surface protein antigen I/II gene, paaB, and a putative transcriptional regulator gene, par, from Streptococcus cricetus.

The flanking region of the antigen I/II gene, paaA, in Streptococcus cricetus was examined using the gene-walking technique. In the region downstream of the paaA gene, another antigen I/II gene designated as paaB was found. The paaB gene was disrupted at the alanine-rich region (A region) by a novel insertion sequence element, ISScr1. ISScr1 is a member of the IS982 family and is composed of a 962-bp sequence and duplicated target DNA (the sequence 5'-TAGCTAAAT-3') resulting from its insertion. To clarify the structural divergence of the two antigen I/II proteins (PAaA and PAaB), computational analysis of the paaB gene was performed and the two structures were compared. The amino acid sequence homology indicated that PAaB resembled PAaA, but the middle region showed little similarity to that of PAaA. Phylogenetic analysis showed that PAaB was better classified in a major group with S. mutans PAc and S. gordonii SspA and SspB than with PAaA. The transcriptional expression of paaA and paaB was demonstrated by reverse transcription (RT)-PCR. In the region upstream of the paaA gene, three genes homologous to the genes located in the region upstream of the S. sobrinus antigen I/II gene (pag) were found. Of the three genes, ORF3 showed homology to the par gene encoding a transcriptional repressor for the pag gene in S. sobrinus. Therefore, ORF3 was designated the par gene of S. cricetus. Southern hybridization revealed that the par gene of S. cricetus was not found in other oral streptococci examined in this study.

Amino Acid Sequence↗

PubMed1993

Calcification of a cariogenic Streptococcus and of Corynebacterium (Bacterionema) matruchotii.

The main aim of this investigation was to challenge the idea that cariogenic streptococci do not calcify. Calcium uptake of calcification of Streptococcus mutans C180-2, proven to be an acidogenic and cariogenic strain, was compared with calcium uptake and calcification of Corynebacterium (Bacterionema) matruchotii, known as a ready calcifier. Bacteria were grown on Brain Heart Infusion Agar (BHIA) and on well-buffered semi-synthetic E-agar, both containing 1.4 mmol/L calcium, 2 g/L glucose, initial pH 7.4. Calcium uptake from BHIA by C. matruchotii (25 mmol Ca/kg wet bacterial cell mass), but not by S. mutans, was found. Grown as a plaque-like lawn on E-agar, the S. mutans cell mass concentrated calcium to 63 +/- 11 mmol/kg compared with 145 +/- 61 mmol/kg in C. matruchotii. X-ray diffraction confirmed the presence of crystalline apatite in the bacterial cell masses. Electron microscopy revealed crystals and mineralized deposits in both organisms. Heavy calcifications in some cells of S. mutans were seen. Calcification was partly inhibited by magnesium ion and by methanehydroxybisphosphonate. S. sobrinus 6715, as well as freshly isolated S. mutans and S. sobrinus from patients, concentrated very large quantities of calcium, up to 500-fold from the medium, when maintained for several weeks on E-agar of initial pH 7.6. Our observations widen the view on acidogenic bacteria as mineralization agents and support the notion that members of the mutans group of streptococci may be involved in events that trigger heavy intracellular calcifications and, possibly, dental calculus formation.

Agar↗