| 1. |
- Lindh, Liselott, et al.
(författare)
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Adsorption from human saliva : time dependence and major components
- 2002
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Ingår i: Journal of Dental Research Conferens;81.
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Konferensbidrag (refereegranskat)abstract
- Objectives: The aims of the present study were to investigate the adsorption from human whole saliva to solid surfaces in terms of dependence of adsorption time and surface wettability, to investigate pellicle elutability with buffer and sodium dodecyl sulphate (SDS) and finally to identify major components involved. Methods: Time resolved in situ ellipsometry was used to determine the adsorbed amounts and adsorption rates from human whole saliva onto pure (hydrophilic) and methylated (hydrophobized) silica surfaces. Two-dimensional gel electrophoresis was used to identify salivary components in the secretions as well as major components in pellicles. Results: The results demonstrated that on hydrophobic surfaces the initial adsorption was rapid and a plateau was reached, whereas on hydrophilic ones a continuous increase was observed during the time course of experiments. Contrary to what was expected, it was found that buffer rinsing removed less material after short adsorption times on hydrophobic surfaces, whereas less time dependence was observed on hydrophilic ones. After SDS exposure a minor fraction remained adsorbed after 15 minutes of adsorption, while a complete removal of the adsorbed film was observed after 2 hours of adsorption on hydrophobic surfaces. On hydrophilic surfaces a minor fraction remained adsorbed after both 15 minutes and 2 hours of adsorption. The two-dimensional gel electrophoresis revealed the presence of more than 50 proteins, with a molecular mass below 200 kDa present in whole saliva. Of these proteins only a few components were detected in the fraction eluted by SDS. Conclusions: We conclude that the different desorbability upon buffer rinsing and addition of SDS indicate that adsorbed proteins have varying binding strengths to the two types of surfaces. The time dependence observed and the compositional analysis show that the adsorbed pellicle undergoes conformational and/or compositional changes.
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| 2. |
- Neilands, Jessica, et al.
(författare)
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Effect of acid shock on protein expression by biofilm cells of Streptococcus mutans
- 2003
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Ingår i: FEMS Microbiology Letters. - : Blackwell, Oxford. - 0378-1097 .- 1574-6968. ; 227:2, s. 287-293
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Tidskriftsartikel (refereegranskat)abstract
- Streptococcus mutans is a component of the dental plaque biofilm and a major causal agent of dental caries. Log-phase cells of the organism are known to induce an acid tolerance response (ATR) at sub-lethal pH values ( approximately 5.5) that enhances survival at lower pH values such as those encountered in caries lesions. In this study, we have employed a rod biofilm chemostat system to demonstrate that, while planktonic cells induced a strong ATR at pH 5.5, biofilm cells were inherently more acid resistant than such cells in spite of a negli-gible induction of an ATR. Since these results suggested that surface growth itself triggered an ATR in biofilm cells, we were interested in comparing the effects of a pH change from 7.5 to 5.5 on protein syn-thesis by the two cell types. For this, cells were pulse labeled with [(14)C]-amino acids following the pH change to pH 5.5, the proteins extracted and separated by two-dimensional (2D) electrophoresis fol-lowed by autoradiography and computer-assisted image analysis. A comparison between the cells incubated at pH 5.5 and the control biofilm cells revealed 23 novel proteins that were absent in the control cells, and 126 proteins with an altered relative rate of synthesis. While the number of changes in protein expression in the biofilm cells was within the same range as for planktonic cells, the magnitude of their change was significantly less in biofilm cells, supporting the observa-tion that acidification of biofilm cells induced a negligible ATR. Mass spectrometry and computer-assisted protein sequence analysis revealed that ATR induction of the planktonic cells resulted in the downregula-tion of glycolytic enzymes presumably to limit cellular damage by the acidification of the external environment. On the other hand, the gly-colytic enzymes in control biofilm cells were significantly less down-regulated and key enzymes, such as lactate dehydrogenase were upregulated during pH 5.5 incubation, suggesting that the enhanced acid resistance of biofilm cells is associated with the maintenance of pH homeostasis by H+ extrusion via membrane ATPase and increased lactate efflux.
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| 3. |
- Svensäter, Gunnel, et al.
(författare)
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Protein expression by planktonic and biofilm cells of Streptococcus mutans
- 2001
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Ingår i: FEMS Microbiology Letters. - : Elsevier. - 0378-1097 .- 1574-6968. ; 205:1, s. 139-146
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Tidskriftsartikel (refereegranskat)abstract
- Streptococcus mutans, a major causal agent of dental caries, functions in nature as a component of a biofilm on teeth (dental plaque) and yet very little information is available on the physiology of the organism in such surface-associated communities. As a consequence, we undertook to examine the synthesis of proteins by planktonic and biofilm cells growing in a biofilm chemostat at pH 7.5 at a dilution rate of 0.1 h(-1) (mean generation time=7 h). Cells were incubated with (14)C-labelled amino acids, the proteins extracted and separated by two-dimensional electrophoresis followed by autoradiography and computer-assisted image analysis. Of 694 proteins analysed, 57 proteins were enhanced 1.3-fold or greater in biofilm cells compared to planktonic cells with 13 only expressed in sessile cells. Diminished protein expression was observed with 78 proteins, nine of which were not expressed in biofilm cells. The identification of enhanced and diminished proteins by mass spectrometry and computer-assisted protein sequence analysis revealed that, in general, glycolytic enzymes involved in acid formation were repressed in biofilm cells, while biosynthetic processes were enhanced. The results show that biofilm cells possess novel proteins, of as yet unknown function, that are not present in planktonic cells.
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| 4. |
- Svensäter, Gunnel, et al.
(författare)
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The acid-tolerant microbiota associated with plaque from initial caries and healthy tooth surfaces
- 2003
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Ingår i: Caries Research. - : S. Karger AG. - 0008-6568 .- 1421-976X. ; 37:6, s. 395-403
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The intent of this study was to compare the inherent acid tolerance of bacteria in samples of dental plaque from tooth sites in subjects with and without initial caries. Plaque was collected from approximal surfaces showing early enamel caries and from healthy tooth surfaces in the same subjects, as well as from enamel surfaces of caries-free individuals. In addition to plating on blood agar, the plaque samples were plated directly on non-selective solid agar medium buffered to pH 7.0, 6.0, 5.5, 5.0, 4.5 and 4.0 to avoid any loss of adaptation to acid during primary isolation of plaque bacteria. The results showed that approximately 50% of the total cultivable plaque microbiota from caries, as well as healthy tooth sites, was able to grow at pH 5.5 and 1% at pH 5.0, pH values regarded as critical for the demineralization of tooth enamel. At pH 5.0, members of the genus Streptococcus were the dominant group, but mutans streptococci accounted for less than half of the streptococcal viable count. The other acid-tolerant streptococcal isolates included Streptococcus anginosus, Streptococcus constellatus, Streptococcus gordinii, Streptococcus intermedius, Streptococcus mitis, Streptococcus oralis, Streptococcus salivarius and SStreptococcus sanguis. Analysis of the results indicated that the mutans streptococci in dental plaque were highly variable with respect to acid tolerance, and that both caries and healthy sites harboured significant numbers of mutans streptococci that were not acid-tolerant.
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| 5. |
- Welin, J, et al.
(författare)
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Protein expression by Streptococcus mutans during initial stage of biofilm formation
- 2004
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Ingår i: Applied and Environmental Microbiology. - : American Society for Microbiology. - 0099-2240 .- 1098-5336. ; 70:6, s. 3736-3741
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Tidskriftsartikel (refereegranskat)abstract
- Cells growing on surfaces in biofilms exhibit properties distinct from those of planktonic cells, such as increased resistance to biocides and antimicrobial agents. In spite of increased interest in biofilms, very little is known about alterations in cell physiology that occur upon attachment of cells to a surface. In this study we have investigated the changes induced in the protein synthesis by contact of Streptococcus mutans with a surface. Log-phase planktonic cells of S. mutans were allowed to adhere to a glass slide for 2 h in the presence of a (14)C-amino acid mixture. Nonadhered cells were washed away, and the adhered cells were removed by sonication. The proteins were extracted from the nonadhered planktonic and the adhered biofilm cells and separated by two-dimensional gel electrophoresis followed by autoradiography and image analysis. Image analysis revealed that the relative rate of synthesis of 25 proteins was enhanced and that of 8 proteins was diminished > or =1.3-fold in the biofilm cells. Proteins of interest were identified by mass spectrometry and computer-assisted protein sequence analysis. Of the 33 proteins associated with the adhesion response, all but 10 were identified by mass spectrometry and peptide mass fingerprinting. The most prominent change in adhered cells was the increase in relative synthesis of enzymes involved in carbohydrate catabolism indicating that a redirection in protein synthesis towards energy generation is an early response to contact with and adhesion to a surface.
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