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PubMed1995

Simultaneous monitoring of intracellular pH and proton excretion during glycolysis by Streptococcus mutans and Streptococcus sanguis: effect of low pH and fluoride.

A system was developed by which 2',7'-bis(carboxyethyl)-4 or 5-carboxyfluorescein could be used to monitor intracellular pH at the same time that proton excretion was being measured. Streptococcal cells were loaded with the dye, and after the addition of glucose protons were excreted and the intracellular pH increased quickly and remained higher than the extracellular pH of 7.0. The excretion of protons stopped and the intracellular pH returned to the original level when glucose was depleted. The intracellular level of ATP remained high during glucose metabolism and decreased with the depletion of glucose. At extracellular pH of 5.5, and 5.0, the intracellular pH of fasting cells was higher than the extracellular pH value. After addition of glucose there were initial lags of proton excretion and of increases in intracellular pH at the acidic extracellular pH values. In the presence of fluoride, a lag in proton excretion and a simultaneous decrease in intracellular pH were observed, indicating a partial and transient inhibition of proton-ATPase activity.

Adenosine Triphosphate↗
PubMed1988

Suppression of Streptococcus sobrinus 6715 (g) in plaques by Streptococcus mutans 32K (c).

The dental plaque of 96 healthy donors was screened for the production of such antibacterial substances as mutalipocin and bacteriocin and 192 strains of mutans streptococci isolated: 28 produced mutalipocin and 22 produced bacteriocin. Mutalipocin produced by these 28 S. mutans strains possessed similar biochemical and biological characteristics of well-characterized mutalipocin-producing strain S. mutans 32K (serotype c). When equal amounts of S. mutans 32K and S. sobrinus 6715 (g) were cultured together, cells of S. sobrinus 6715 were completely killed in 18 h. In addition, S. mutans 32K inhibited in vitro plaque formation by S. sobrinus 6715, and S. mutans 32K also eliminated in vitro plaque preformed by S. sobrinus 6715. In rat experiments, S. mutans 32K could pre-emptively colonize in plaque preformed by S. sobrinus 6715. On the other hand, S. sobrinus 6715 could not colonize in plaque preformed by S. mutans 32K. The results indicate that S. mutans serotype c which produces antibacterial substances is able to invade dental plaque and replace the other mutans streptococci. This investigation offers one of the possible explanation why S. mutans serotype c is a predominant species among mutans streptococci in human plaque.

Animals↗
PubMed1980

Effects of chlorhexidine and iodine on in vitro plaques of Streptococcus mutans and Streptococcus sanguis.

Both chlorhexidine and iodine showed greater antimicrobial effect on in vitro grown S. mutans plaque than on plaque composed of S. sanguis. One treatment with iodine for 8 min inhibited the acid production of S. Mutans plaque whereas S. sanguis plaque required 20 min to be similarly affected. In contrast one treatment with chlorhexidine for up to 20 min did not completely inhibit the acid production of plaque of either microorganism. Repeated short term exposures increased the bactericidal effect of chlorhexidine but not that of iodine. The difference in antimicrobial effect between chlorhexidine and that of iodine on S. mutans and S. sanguis should be investigated in persons heavily infected by S. mutans.

Acids↗
PubMed1977

Interaction of hydroxyapatite and protein-coated hydroxyapatite with Streptococcus mutans and Streptococcus sanguis.

The present study showed that S. mutans and S. sanguis behaved like negatively-charged particles in their interaction with hydroxyapatite in vitro. Phosphate in the system inhibited bacterial uptake by apatite, whereas calcium increased the uptake. A layer of acidic protein inhibited the uptake of bacteria by hydroxyapatite. The opposite was true when a basic protein was first adsorbed to the apatite. A saliva film on the apatite decreased the uptake of bacteria, supporting the view that acidic proteins are selectively adsorbed by hydroxyapatite from saliva. The results indicate clearly that electrostatic forces may be involved in bacterial interaction with tooth surface.

Adsorption↗