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PubMed2006

Effect of MUC7 peptides on the growth of bacteria and on Streptococcus mutans biofilm.

OBJECTIVES: To investigate the susceptibility of selected bacteria as well as Streptococcus mutans biofilm to MUC7 peptides and compare the activities with those of other known antimicrobial peptides. METHODS: MIC and MBC of peptides for S. mutans, Escherichia coli, Streptococcus gordonii, Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis and Pseudomonas aeruginosa were determined using the microdilution method. For S. mutans, the effects of the peptides on the kinetics of growth inhibition, time-killing, and on biofilm formation and reduction were also examined. For biofilm studies, polystyrene microtitre plates, Calgary Biofilm Device (CBD) and hydroxylapatite (HA) discs, along with Crystal Violet and Alamar Blue dyes, and/or EM observations, were employed. RESULTS: S. mutans was the most susceptible to all peptides tested (MICs of 9.4-25.0 microM), compared with the other species (MICs of 3.1->100 microM). MUC7 peptides (except MUC7-12-mer-L4) exerted 2-fold higher activity against S. mutans than Hsn5-12-mer and magainin-II, and faster killing of S. mutans than Hsn5-12-mer. The MUC7 peptides also had an effect on S. mutans biofilm. On the polystyrene plates, they suppressed the biofilm formation, with MBIC(50) of 6.25-12.5 microM, and reduced the 1 day developed biofilm in a batch culture, with MBRC(50) of 25-50 microM. On the CBD pegs, the viabilities of the biofilm were suppressed by >95% in the presence of MUC7 peptides at 4x MIC (50 microM). One day developed biofilm viabilities were inhibited by 49-75%. On HA, the formation of biofilm (as observed by EM) was also considerably reduced. CONCLUSIONS: MUC7 peptides present somewhat preferential antimicrobial activity against S. mutans. They also have an effect on in vitro formation and reduction of the preformed S. mutans biofilm.

Anti-Bacterial Agents↗
PubMed2002

PCR detection of Streptococcus mutans and S. sobrinus in dental plaque samples from Japanese pre-school children.

Streptococcus mutans and S. sobrinus are associated with the development of dental caries. These bacteria were detected by PCR and then their presence was compared with the incidence of dental caries in 77 Japanese pre-school children. Plaque samples were collected from all erupted tooth sites in the subjects, aged 3-5 years old and each with primary dentition, with a sterile toothbrush. A dental examination was performed for dmft (decayed, missing, filled, total) with the WHO caries diagnostic criteria. In all subjects, the prevalence of S. mutans and S. sobrinus was 72.8% and 61.1%, respectively; 19 (24.7%) were positive for S. mutans alone, 10 (13.0%) were positive for S. sobrinus alone, 37 (48.1%) were positive for both S. mutans and S. sobrinus, and 11 (14.3%) were negative for both S. mutans and S. sobrinus. The dmft scores of children positive for both S. mutans and S. sobrinus were significantly higher than those positive for S. mutans alone. These results indicate that children harbouring both S. mutans and S. sobrinus have a significantly higher incidence of dental caries than those with S. mutans alone.

Age Distribution↗
PubMed1982

The acquisition of Streptococcus mutans by infant monkeys (Macaca fascicularis) and its relationship to the initiation of dental caries.

The acquisition and transmission of Streptococcus mutans by 16 consecutively born infant monkeys (Macaca fascicularis) was studied. The 16 infant monkeys were weaned in four groups and caged together to form a commune. Transmission from mother to infant occurred infrequently. Streptococcus mutans was isolated from nine of the mothers but only from the dental plaque of two infant monkeys at weaning at which time the predominant streptococci were S. sanguis and S. mitior. One further animal was colonized by S. mutants during the formation of the commune, but only after it was caged with an infant harbouring the same organism. For 46 d after the completion of the commune, the monkeys were fed a starch-based diet during which time S. mutans of serotypes c, e or h were isolated from the faeces of all 16 animals and from the dental plaque taken from the developmental groove of the first deciduous molar of 11 animals. Faecal transmission appeared to be an important factor in the spread of S. mutans between monkeys in the commune. The monkeys were then fed a caries-promoting high sucrose diet resulting in a rapid increase in the proportion of S. mutans in the plaque and in the faeces. Streptococcus mutans serotype e was more frequently isolated from both plaque and faeces and its predominance may in part be due to the production of a bacteriocin active in vitro against S. mutans serotype h and other species of oral streptococci isolated from monkey dental plaque. The proportion of S. mutans in the developmental groove 8 d after the introduction of the high sucrose diet was significantly related to both the caries status of the groove and the total caries score 6 months later. The results suggest that, in this model of human dental caries, S. mutans is the major bacterial factor in the initiation of tooth decay.

Aging↗
PubMed2001

Expression of Streptococcus mutans fimA is iron-responsive and regulated by a DtxR homologue.

Iron uptake, transport and storage in Streptococcus mutans, the principal causative agent of human dental cavities, is unexplored despite early reports in the literature which predict a role for this trace metal in cariogenesis. Experiments in the authors' laboratory revealed several iron-responsive proteins in S. mutans, one of which reacted with a polyclonal antiserum directed against the FimA fimbrial adhesin from Streptococcus parasanguis on Western blots. The results of Western blot and Northern hybridization experiments support an inverse relationship between iron availability and S. mutans fimA expression, and metal ion uptake experiments implicate FimA in S. mutans (55)Fe transport. Cloning of the S. mutans fimA homologue facilitated the construction of a fimA knockout mutant which grew poorly in an iron-limiting medium relative to the wild-type progenitor strain, lending further support to a role for FimA in S. mutans iron transport. The authors also identified and cloned a dtxR-like gene (dlg) located downstream of fimA on the S. mutans chromosome, and noted increased fimA expression in a S. mutans dlg knockout mutant relative to wild-type on RNA spot blots and Western blots. The uptake of (55)Fe, which was also significantly increased in this mutant, was compromised in a fimA/dlg double knockout. These findings are consistent with a role for Dlg in the iron-mediated regulation of fimA, and possibly other S. mutans iron transporters. Finally, the cariogenic potential of the fimA and dlg knockout mutants was not significantly different from that of the wild-type progenitor in a germ-free rat model.

Bacterial Proteins↗
PubMed2005

Longitudinal study of dental caries incidence associated with Streptococcus mutans and Streptococcus sobrinus in pre-school children.

Streptococcus mutans and Streptococcus sobrinus are known to be associated with the development of dental caries. In this study these bacteria were detected in pre-school children (each with primary dentition, age range 3-5 years, n = 60) using a PCR method, and then their presence was compared with the incidence of dental caries over a 1-year period. Plaque samples were collected from all erupted tooth sites using a sterile toothbrush. Dental examinations at the beginning of the study (baseline) and after 1 year were also performed to determine decayed, missing, filled teeth (dmft) scores using WHO caries diagnostic criteria. The prevalences of S. mutans and S. sobrinus across all the subjects were 61.7% and 56.6%, respectively; 13 subjects (21.7%) were positive for S. mutans alone, 10 (16.6%) were positive for S. sobrinus alone and 24 (40.0%) were positive for both S. mutans and S. sobrinus, whereas 13 (21.7%) were negative for both S. mutans and S. sobrinus. dmft scores of subjects positive for both S. mutans and S. sobrinus at baseline and after 1 year were significantly higher than of those positive for S. mutans alone at the same stages (P < 0.01 and P < 0.001, respectively). The caries incremental increase was also significantly greater in those with both bacteria detected (P < 0.05). Our results indicate that pre-school children harbouring both S. mutans and S. sobrinus have a significantly higher incidence of dental caries than those with S. mutans alone.

Child, Preschool↗
PubMed1994

Effect of antibody in gingival crevicular fluid on early colonization of exposed root surfaces by mutans streptococci.

The effect of antibody to Streptococcus mutans in gingival crevicular fluid (GCF) on the recolonization of cleaned buccal root surface sites by indigenous mutans streptococci was studied. Seven subjects (mean age = 64 years) were selected from a population of 28 on the basis of the presence of appropriate sites with and without detectable immunoglobulin G (IgG) antibody in GCF to formalin-killed S. mutans and adequate levels of mutans streptococci in saliva available for root surface recolonization. Root surfaces exposed to GCF that did or did not contain antibody were then cleaned and sampled for residual plaque organisms (total cultivable flora and mutans streptococci) directly after cleaning (time 0) as well as 24 h later. One subject failed to recolonize at 24 h at any (antibody-positive or antibody-negative) experimental site. For each of the remaining 6 subjects, the mean levels of mutans streptococci (mean percentage of total flora) were lower at sites with IgG antibody to S. mutans in GCF than at antibody-negative sites in the same subject. In each of the 6 subjects, the site with the highest recolonization level was antibody-negative. Comparison based on intrasubject randomization of sites suggested diminished recolonization of mutans streptococci at sites with antibody 24 h after cleaning. The results support the idea that antibody in GCF can modify the early colonization of gingival root surface areas by potentially cariogenic plaque bacteria such as mutans streptococci.

Aged↗
PubMed1998

Incidence of mutans streptococci and lactobacilli in oral cleft children wearing acrylic plates from shortly after birth.

Children with a palatal cleft can be treated with preoperative infant orthopedics including an acrylic plate that is applied shortly after birth to obturate the cleft. It is advised to wear these plates until the 18th month of age. Such a plate, being a hard non-shedding surface, may be expected to facilitate early colonization of mutans streptococci. The first aim of the present investigation was to assess the incidence of mutans streptococci and lactobacilli in children with cleft lip and/or palate during the first 2 years of life. The second aim was to study whether preoperative orthopedics, that is, the wearing of an acrylic plate, had facilitated the establishment of mutans streptococci and lactobacilli. The third aim was to determine other factors associated with colonization of these organisms in these children. Sixty-two Caucasian Dutch children with cleft lip and/or palate participated in this study. Twenty-four of these children were treated with preoperative infant orthopedics and had been wearing an acrylic plate from within a few days after birth. At regular control visits plaque and saliva samples and samples from the surface of the acrylic plate were taken, while a dental examination was performed to document the emergence of the primary teeth, caries status, gingival condition and oral hygiene procedures. Saliva samples were also taken from the accompanying parents. At the visit at the age of 18 months, the parents were interviewed using a structured questionnaire. At this age, the prevalence of mutans streptococci and lactobacilli was compared to that in a control group of non-cleft children. The oral cleft children wearing an acrylic plate from shortly after birth were colonized earlier with mutans streptococci and lactobacilli than the non-plate oral cleft children. In the children wearing acrylic plates, the prevalence of lactobacilli decreased with age, while the prevalence of mutans streptococci increased. At the age of 18 months the prevalence of mutans streptococci was comparable in both groups of oral cleft children and in the control children. There was no relation between the numbers of mutans streptococci in the saliva of the mothers and their children. The presence of mutans streptococci in the saliva of the oral cleft children was significantly associated with between-meal snacking and with the presence of lactobacilli.

Acrylic Resins↗
PubMed1998

Differential activation of human neutrophils by Streptococcus mutans isolates from root surface lesions and caries-free and caries-active subjects.

Phagocytosis of bacterial pathogens is an important defense mechanism and may contribute to regulating Streptococcus mutans-induced dental caries, particularly at root surfaces. This study was undertaken to examine and compare differences in polymorphonuclear leukocyte or neutrophil activation by clinical isolates of S. mutans collected from the saliva of caries-free or caries-active individuals with S. mutans isolates from root surface lesions. S. mutans clinical isolates (5 caries-free, 5 caries-active, 5 root caries isolates and a laboratory strain) were incubated with neutrophils in the presence of normal human serum and the luminol dependent chemiluminescence was measured for 1 h at 37 degrees C. Results indicated that the caries active and laboratory strains activated neutrophils equally. The mean integration stimulated by caries-free strains, however, displayed a 25-30% enhanced neutrophil activation over the caries-active and laboratory strains. In contrast, neutrophil activation by root caries strains of S. mutans was 45-50% lower than all other S. mutans strains, possibly suggesting a natural selection for S. mutans strains that can evade neutrophil recognition and subsequent phagocytosis. Stimulation of neutrophils with the cell wall and membrane surface component preparations indicated that extracts from all four groups activated neutrophils significantly. Again, caries-free preparations activated neutrophils significantly more than caries active, laboratory strain and root caries isolates. This selection may become more important on root surfaces due to increased exposure to crevicular fluid and neutrophils. The data provide evidence for the presence or onset of mechanisms or biological alterations in S. mutans developed to circumvent neutrophil recognition and/or phagocytosis, thus increasing S. mutans survival and colonization on tooth surfaces, resulting in an enhanced risk of dental caries, particularly at root surfaces.

Adult↗
PubMed2005

Differentiation of mutans streptococci by intact cell matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

It is difficult to distinguish mutans streptococci on the species level, and even more so on the subspecies level. Intact cell matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) (ICM) was applied to reference strains of five of the species of the mutans group (Streptococcus criceti, Streptococcus downei, Streptococcus mutans, Streptococcus ratti, Streptococcus sobrinus), nonmutans streptococci (Streptococcus oralis, Streptococcus mitis, Streptococcus salivarius, and Streptococcus sanguinis), and 177 mutans streptococci isolated from saliva of 10 children. From the analysis of the reference strains, readily distinguishable ICM mass spectra were obtained for the different species. Based on multivariate statistical analysis, a correct and unambiguous assignment was made of the spectra of 159 isolated mutans streptococci to S. mutans and 16 isolates to S. sobrinus. Two isolates were sorted out and were identified by sequencing of their 16S rRNA genes as Streptococcus anginosus. In addition, ICM indicated a misclassification for some reference strains (AHT, V 100 and E 49) and re-classified AHT and E 49 as S. ratti and V 100 as S. sobrinus. This was confirmed by 16S rDNA sequencing. Based on a statistical similarity analysis of the spectra of reference strains and a quantitative assessment of the reproducibility of ICM, the isolates identified as either S. mutans or S. sobrinus were phenotyped on the subspecies level. In the population of the clinical isolates, 14 unambiguously different S. mutans and three different S. sobrinus phenotypes were detected. ICM proved to be a powerful tool for a differentiation of mutans streptococci down to the subspecies level.

Child↗
PubMed1991

Interactions between and within Streptococcus mutans and Streptococcus sobrinus isolated from humans harboring both species.

The prevalence of Streptococcus mutans and Streptococcus sobrinus was examined in plaque samples from small discrete areas of the buccal tooth surfaces of seven subjects. Strains of S. mutans and S. sobrinus were isolated and tested for bacteriocin-mediated interactions between and within the two species, using the stab inoculation technique. S. mutans and S. sobrinus did not colonize each tooth surface uniformly and, in plaque from small discrete sites, S. mutans and S. sobrinus were either undetected or present in different interspecies proportions. Within the same subject, there were no bacteriocin-mediated interactions between strains of the same mutans species and no difference in bacteriocin activity was found between the strains of S. mutans and S. sobrinus from different sites. When bacteriocin interactions were tested between isolated strains from all seven subjects a somewhat higher inhibition ability was found for producer strains isolated from plaque compared with those isolated from saliva. S. mutans appeared to be more bacteriocinogenic than S. sobrinus. Replacing the glucose in the medium with sucrose enhanced the bacteriocin activity of S. mutans towards other S. mutans strains but reduced the inhibitory interaction towards strains of S. sobrinus.

Adult↗
PubMed2006

The effect of cocoa polyphenols on the growth, metabolism, and biofilm formation by Streptococcus mutans and Streptococcus sanguinis.

The aim of this study was to determine if cocoa polyphenols could interfere with biofilm formation by Streptococcus mutans or Streptococcus sanguinis, and reduce acid production from sucrose by S. mutans. The antimicrobial activity of cocoa polyphenols was assessed against cariogenic (S. mutans) and health-associated (S. sanguinis) species by minimum inhibitory concentration assays. Cocoa polyphenol dimer, tetramer, and pentamer inhibited the growth of S. sanguinis, whereas the growth of S. mutans was unaffected. However, pretreatment of surfaces with cocoa polyphenol pentamer (35 microM) reduced biofilm formation by S. mutans at 4 and 24 h, whereas the effects on S. sanguinis were less consistent. In contrast, brief exposure of preformed biofilms to pentamer either had no significant effect or resulted in increased counts of S. mutans under certain conditions. Cocoa polyphenol pentamer (500 microM) significantly reduced the terminal pH, and inhibited the rate of acid production by S. mutans at pH 7.0. In conclusion, cocoa polyphenols can reduce biofilm formation by S. mutans and S. sanguinis, and inhibit acid production by S. mutans.

Acids↗
PubMed1977

Effective immunity to dental caries: passive transfer to rats to antibodies to Streptococcus mutans elicits protection.

Rat dams, given intravenous injections of heat-killed Streptococcus mutans 6715, mutant C211 demonstrated significant agglutinin activity to the homologous S. mutans in colostrum, milk, and serum. This antibody activity was associated with the immunoglobulin G (IgG) class. High titers of anti-S. mutans antibody associated with the IgG class were also exhibited in the sera and saliva of the offspring that suckled these dams. After challenge with the homologous, live S. mutans, these offspring developed significantly fewer caries on all molar surfaces than did nonimmunized infected controls. A secretory immune response (manifested by the presence of specific IgA antibody to S. mutans in colostrum and milk) was elicited (i) in rat dams locally injected, in the region of the mammary gland, with heat-killed S. mutans antigen, and (ii) in other rat dams that were provided formalin-killed S. mutans in their drinking water. Offspring suckling these dams were challenged with virulent S. mutans before weaning and developed significantly fewer caries than did their infected controls. These findings clearly suggest that passively derived IgG or IgA antibodies to S. mutans are protective against dental caries.

Administration, Oral↗
PubMed1978

Colonization of teeth in humans by Streptococcus mutans as related to its concentration in saliva and host age.

The relationship of the salivary concentration of Streptococcus mutans and host age to the colonization of this organism on erupting teeth was studied in humans. Plaques were obtained from fissures and buccal surfaces of erupting permanent first and second molars of children 6 to 7 and 11 to 14 years old, respectively. In subjects of both age groups with salivary S. mutans concentrations below 5 x 10(2) colony-forming units per ml, the organism was detected on only a few of the tooth surfaces; at concentrations of 5 x 10(2) to 4.9 x 10(4) colony-forming units per ml more than half of the surfaces and at concentrations of 5 x 10(4) colony-forming units per ml or higher most of the surfaces were colonized by S. mutans. The frequency of detection and concentration of S. mutans in plaque as well as its concentration in saliva were higher in the case of the older children. However, when younger and older children with similar salivary S. mutans concentrations were compared, S. mutans was more frequently isolated from plaque from older children only in the case of children with below 5 x 10(2) colony-forming units per ml of saliva. Eleven of the 64 children studied had low or undetectable S. mutans levels in plaque and saliva. The salivary S. mutans levels of the parents of these children were lower than those of parents of a group of children with normal oral S. mutans levels.

Adolescent↗
PubMed1980

Virulence of Streptococcus mutans: restoration of pathogenesis of a glucosyltransferase-defective mutant (C4).

Previous studies have shown that a mutant (designated C4) of Streptococcus mutans 6715 wild type (WT) is defective in glucosyltransferase (GTF)-synthesized insoluble glucan and is avirulent in gnotobiotic rats. This study investigated the factors which would render this mutant virulent in gnotobiotic rats. Microbial analysis of plaque from gnotobiotic rats (45 days old) infected with a mixture of C4 and virulent S. mutans PS-14 (approximately 15,000 C4 organisms to each S. mutans PS-14) yielded higher numbers of C4 organisms than S. mutans PS-14. These animals exhibited significantly lower caries scores than did gnotobiotic rats (age, 45 days) monoassociated with S. mutans PS-14. Similar mixed infection studies using C4 and an avirulent, aggregation-defective mutant of S. mutans 6715 WT (designated UAB 165) which exhibits GTF activity similar to that of the parent strain resulted in plaque consisting almost exclusively of UAB 165 and low caries activity. However, high levels of both C4 and UAB 165 in plaque and high caries activity were observed in gnotobiotic rats infected at weaning with C4 followed by UAB 165 3 days later. When dried S. mutans 6715 WT culture supernatant containing GTF activity was mixed with diet provided rats monoassociated with C4, significant caries activity was observed. Insoluble glucan supplemented in diet did not restore C4 to virulence; however, admixture of suboptimal GTF-rich supernatant with insoluble glucan and C4 resulted in high caries activity in gnotobiotic rats. These results suggest that in vivo restoration of pathogenesis of a GTF-defective mutant of S. mutans can be achieved either by complementation with a mutant defective in aggregation properties or by providing exogenous GTF and glucan from the parent S. mutans 6715 WT.

Animals↗
PubMed1981

Oral ecology and virulence of Lactobacillus casei and Streptococcus mutans in gnotobiotic rats.

Lactobacilli comprise a small percentage of the normal oral microbial flora of humans and are isolated commonly from saliva and frequently from an active caries lesion. We have compared the pathogenesis and colonization pattern of Lactobacillus casei with that of Streptococcus mutans strain 6715 in gnotobiotic rats. Of the two L. casei strains tested, L. casei strain ATCC 4646 caused slightly more caries than L. casei strain ATCC 11578. However, the level of caries induced by either L. casei strain was significantly lower (P less than 0.01) than that observed in similar-aged rats monoassociated with S. mutans strain 6715. When groups of rats were infected with mixtures of L. casei strain ATCC 4646 and S. mutans strain 6715, or with L. casei followed by S. mutans, higher numbers of L. casei than S. mutans were found associated with the tongue and in saliva; S. mutans always predominated in plaque. The level of caries observed in these groups of rats was similar to that seen with rats monoassociated with S. mutans except when L. casei comprised greater than 1% of the plaque microflora. In this latter situation, the level of caries was significantly lower (P less than or equal to 0.05) than that obtained in S. mutans-monoassociated rats. The results of this study suggest that L. casei colonizes sites in the oral cavity (including the tongue and saliva) other than the tooth surface in rats. The effect of L. casei in plaque toward reduction of S. mutans-induced dental caries in rats is discussed.

Animals↗
PubMed1982

Streptococcus mutans genes that code for extracellular proteins in Escherichia coli K-12.

Chromosomal DNA from Streptococcus mutans 6715 (serotype g) was cloned into Escherichia coli K-12 by using the cosmid pJC74 cloning vector and a bacteriophage lambda in vitro packaging system. Rabbit antiserum against S. mutans extracellular proteins was used for immunological screening of the clone bank. Twenty-one clones produced weak to strong precipitin bands around the colonies, but only after the lambda c1857 prophage was induced by being heated to lyse the E. coli cells. None of the clones expressed enzyme activity for several known S. mutans extracellular enzymes. One of these clones contained a 45-kilobase recombinant plasmid designated pYA721. An 8.5-kilobase fragment of S. mutans DNA from pYA721 was isolated and recloned into the BamHI restriction site of the plasmid vector pACYC184 to construct pYA726. pYA726 contained all, or nearly all, of the gene for a surface protein antigen (the spaA protein) of S. mutans 6715. This was deduced from immunological studies in which extracts of cells harboring pYA726 reacted with antisera against both purified 6715 spaA protein (about 210,000 daltons) and the immunologically similar antigen I/II of serotype c strains of S. mutans. In addition, the S. mutans spaA protein was found to possess at least one antigenic determinant not present on the protein specified by pYA726. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of E. coli clone extracts revealed that pYA726 produced a polypeptide with a molecular mass of about 180,000 daltons which was predominantly found in the periplasmic space of E. coli cells. Antisera to the spaA protein of S. mutans reacted with extracellular protein from representative strains of S. mutans serotypes a, c, d, e, f, and g, but not b.

Antigens, Bacterial↗
PubMed1986

Transformation of Streptococcus mutans with chromosomal and shuttle plasmid (pYA629) DNAs.

Transformation (i.e., DNase-sensitive genetic transfer) of strains of Streptococcus mutans representing serotypes c and e was accomplished by using chromosomal DNA from a Rifr Strr Spcr isolate of strain GS5 (UAB525) and a chimeric plasmid, pYA629. Shuttle plasmid pYA629 comprises the S. mutans plasmid pVA318, an inducible erythromycin resistance determinant originally isolated from a group A streptococcal strain, the tetracycline resistance gene and replication region of the Escherichia coli plasmid pBR322, and the promoter region of the S. mutans gene for aspartate beta-semialdehyde dehydrogenase. The strains examined for recipient ability included those known to lack a cryptic plasmid (GS5, UA130, UA159, and MT8148) and those known to contain a widely disseminated 5.8-kilobase cryptic plasmid (LM7, V318, UA101, UA174, and 3098791). The transformation frequencies in GS5 for GS5 chromosomal antibiotic resistance markers were comparable to those reported by others, but UA101, UA130, UA159 and UA174 were transformed with both chromosomal and plasmid markers at much higher efficiencies. In a larger strain survey, strains containing the 5.8-kilobase cryptic plasmid were more frequently transformable with both chromosomal and pYA629 DNAs than were strains lacking this cryptic plasmid. All plasmid-containing strains except LM7 lost their resident cryptic plasmids when transformed with pYA629. LM7 transformed with pYA629 retained pLM7. There are therefore at least two incompatibility groups among S. mutans cryptic plasmids. yPA629 DNA isolated from either E. coli or S. mutans transformed S. mutans with equal efficiency. pYA629 DNA isolated from S. mutans transformed both restriction-deficient and restriction-proficient E. coli recipients. Therefore, the strains of S. mutans used lack a restriction-modification system for pYA629 DNA sequences. S. mutans strains that are readily transformable, display maximal cariogenicity in gnotobiotic rats, and give high scores for in vitro measures of important virulence attributes have been identified to facilitate studies on the genetic basis and control of virulence.

Animals↗
PubMed1993

Collagen mediates adhesion of Streptococcus mutans to human dentin.

Some strains of Streptococcus mutans were found to recognize and bind collagen type I. Binding of 125I-labeled collagen type I was specific in that collagen types I and II, but not unrelated proteins, were able to inhibit binding of the labeled ligand to bacteria. Collagen binding to S. mutans was partially reversible and involved a limited number of bacterial binding sites per cell. S. mutans UA 140 cells bound collagen type I with high affinity (Kd = 8 x 10(-8) M). The number of binding sites per cell was 4 x 10(4). Collagen-binding strains of S. mutans were found to adhere to collagen-coated surfaces as well as to pulverized root tissue. S. mutans strains that did not bind the soluble ligand were unable to adhere to these substrata. Adherence to collagen-coated surfaces could be inhibited with collagen or clostridial collagenase-derived collagen peptides. Adherence of S. mutans to dentin was enhanced by collagen types I and II but inhibited by collagen peptides. S. mutans UA 140 bound significantly less 125I-collagen type I following treatment with peptidoglycan-degrading enzymes. These enzymes released a collagen-binding protein (collagen receptor) with a relative molecular size of 16 kDa. The results of this study suggest that collagen mediates adhesion of S. mutans to dentin. This interaction may target collagen-binding strains of S. mutans to dentin in the oral cavity and may play a role in the pathogenesis of root surface caries.

Adhesins, Bacterial↗