Role of the luxS Gene in Initial Biofilm Formation by Streptococcus mutans

2015 ◽  
Vol 25 (1) ◽  
pp. 60-68 ◽  
Author(s):  
Zhiyan He ◽  
Jingping Liang ◽  
Zisheng Tang ◽  
Rui Ma ◽  
Huasong Peng ◽  
...  
Keyword(s):  
Streptococcus Mutans ◽  
Mutant Strain ◽  
Biofilm Formation ◽  
Type Strain ◽  
Laser Scanning ◽  
Wild Type Strain ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Wild Type ◽  
Initial Biofilm

Quorum sensing (QS) is a process by which bacteria communicate with each other by secreting chemical signals called autoinducers (AIs). Among Gram-negative and Gram-positive bacteria, AI-2 synthesized by the LuxS enzyme is widespread. The aim of this study was to evaluate the effect of QS <i>luxS</i> gene on initial biofilm formation by <i>Streptococcus mutans</i>. The bacterial cell surface properties, including cell hydrophobicity (bacterial adherence to hydrocarbons) and aggregation, which are important for initial adherence during biofilm development, were investigated. The biofilm adhesion assay was evaluated by the MTT method. The structures of the 5-hour biofilms were observed by using confocal laser scanning microscopy, and QS-related gene expressions were investigated by real-time PCR. The <i>luxS</i> mutant strain exhibited higher biofilm adherence and aggregation, but lower hydrophobicity than the wild-type strain. The confocal laser scanning microscopy images revealed that the wild-type strain tended to form smaller aggregates with uniform distribution, whereas the <i>luxS</i> mutant strain aggregated into distinct clusters easily discernible in the generated biofilm. Most of the genes examined were downregulated in the biofilms formed by the <i>luxS</i> mutant strain, except the <i>gtfB </i>gene. QS <i>luxS</i> gene can affect the initial biofilm formation by <i>S. mutans.</i>

scholarly journals Cell-to-Cell Signaling in Xylella fastidiosa Suppresses Movement and Xylem Vessel Colonization in Grape

2008 ◽  
Vol 21 (10) ◽  
pp. 1309-1315 ◽  
Author(s):  
Subhadeep Chatterjee ◽  
Karyn L. Newman ◽  
Steven E. Lindow
Keyword(s):  
Cell Signaling ◽  
Type Strain ◽  
Laser Scanning ◽  
Wild Type Strain ◽  
Xylella Fastidiosa ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Deficient Mutant ◽  
Wild Type ◽  
Wide Range

Cell-to-cell signaling mediated by a fatty acid diffusible signaling factor (DSF) is central to the regulation of the virulence of Xylella fastidiosa. DSF production by X. fastidiosa is dependent on rpfF and, although required for insect colonization, appears to reduce its virulence to grape. To understand what aspects of colonization of grape are controlled by DSF in X. fastidiosa and, thus, those factors that contribute to virulence, we assessed the colonization of grape by a green fluorescent protein–marked rpfF-deficient mutant. The rpfF-deficient mutant was detected at a greater distance from the point of inoculation than the wild-type strain at a given sampling time, and also attained a population size that was up to 100-fold larger than that of the wild-type strain at a given distance from the point of inoculation. Confocal laser-scanning microscopy revealed that approximately 10-fold more vessels in petioles of symptomatic leaves harbored at least some cells of either the wild type or rpfF mutant when compared with asymptomatic leaves and, thus, that disease symptoms were associated with the extent of vessel colonization. Importantly, the rpfF mutant colonized approximately threefold more vessels than the wild-type strain. Although a wide range of colony sizes were observed in vessels colonized by both the wild type and rpfF mutant, the proportion of colonized vessels harboring large numbers of cells was significantly higher in plants inoculated with the rpfF mutant than with the wild-type strain. These studies indicated that the hypervirulence phenotype of the rpfF mutant is due to both a more extensive spread of the pathogen to xylem vessels and unrestrained multiplication within vessels leading to blockage. These results suggest that movement and multiplication of X. fastidiosa in plants are linked, perhaps because cell wall degradation products are a major source of nutrients. Thus, DSF-mediated cell-to-cell signaling, which restricts movement and colonization of X. fastidiosa, may be an adaptation to endophytic growth of the pathogen that prevents the excessive growth of cells in vessels.

scholarly journals Effect of arsenite on swimming motility delays surface colonization in Herminiimonas arsenicoxydans

Microbiology ◽  
2010 ◽  
Vol 156 (8) ◽  
pp. 2336-2342 ◽  
Author(s):  
M. Marchal ◽  
R. Briandet ◽  
S. Koechler ◽  
B. Kammerer ◽  
P. N. Bertin
Keyword(s):  
Laser Scanning ◽  
Time Course ◽  
Wild Type Strain ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Wild Type ◽  
Arsenite Oxidase ◽  
Swimming Motility ◽  
In The Wild ◽  
Biofilm Development

Herminiimonas arsenicoxydans is a Gram-negative bacterium able to detoxify arsenic-contaminated environments by oxidizing arsenite [As(III)] to arsenate [As(V)] and by scavenging arsenic ions in an extracellular matrix. Its motility and colonization behaviour have been previously suggested to be influenced by arsenite. Using time-course confocal laser scanning microscopy, we investigated its biofilm development in the absence and presence of arsenite. Arsenite was shown to delay biofilm initiation in the wild-type strain; this was partly explained by its toxicity, which caused an increased growth lag time. However, this delayed adhesion step in the presence of arsenite was not observed in either a swimming motility defective fliL mutant or an arsenite oxidase defective aoxB mutant; both strains displayed the wild-type surface properties and growth capacities. We propose that during the biofilm formation process arsenite acts on swimming motility as a result of the arsenite oxidase activity, preventing the switch between planktonic and sessile lifestyles. Our study therefore highlights the existence, under arsenite exposure, of a competition between swimming motility, resulting from arsenite oxidation, and biofilm initiation.

scholarly journals Assessment of Genes Associated with Streptococcus mutans Biofilm Morphology

2006 ◽  
Vol 72 (9) ◽  
pp. 6277-6287 ◽  
Author(s):  
Mizuho Motegi ◽  
Yuzo Takagi ◽  
Hideo Yonezawa ◽  
Nobuhiro Hanada ◽  
Jun Terajima ◽  
...  
Keyword(s):  
Streptococcus Mutans ◽  
Biofilm Formation ◽  
Laser Scanning ◽  
Protein Gene ◽  
Laser Scanning Microscopy ◽  
Live Cells ◽  
Confocal Laser ◽  
Morphological Development ◽  
Phosphotransferase System ◽  
Whole Saliva

ABSTRACT Streptococcus mutans, the major pathogen responsible for dental caries in humans, is a biofilm-forming bacterium. In the present study, 17 different pulsed-field gel electrophoresis patterns of genomic DNA were identified in S. mutans organisms isolated clinically from whole saliva. The S. mutans isolates showed different abilities to form biofilms on polystyrene surfaces in semidefined minimal medium cultures. Following cultivation in a flow cell system in tryptic soy broth with 0.25% sucrose and staining using a BacLight LIVE/DEAD system, two strains, designated FSC-3 and FSC-4, showed the greatest and least, respectively, levels of biofilm formation when examined with confocal laser scanning microscopy. Further, image analyses of spatial distribution and architecture were performed to quantify the merged green (live cells) and red (dead cells) light. The light intensity of the FSC-3 biofilm was greater than that of the FSC-4 biofilm in the bottom area but not in the top area. S. mutans whole-genome array results showed that approximately 3.8% of the genes were differentially expressed in the two strains, of which approximately 2.2%, including bacitracin transport ATP-binding protein gene glrA and a BLpL-like putative immunity protein gene, were activated in FSC-3. In addition, about 1.6% of the genes, including those associated with phosphotransferase system genes, were repressed. Analyses of the glrA-deficient strains and reverse transcription-PCR confirmed the role of the gene in biofilm formation. Differential assessment of biofilm-associated genes in clinical strains may provide useful information for understanding the morphological development of streptococcal biofilm, as well as for colonization of S. mutans.

scholarly journals The vicK gene of Streptococcus mutans mediates its cariogenicity via exopolysaccharides metabolism

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Yalan Deng ◽  
Yingming Yang ◽  
Bin Zhang ◽  
Hong Chen ◽  
Yangyu Lu ◽  
...  
Keyword(s):  
Dental Caries ◽  
Streptococcus Mutans ◽  
Biofilm Formation ◽  
Laser Scanning ◽  
Single Species ◽  
Laser Scanning Microscopy ◽  
Gas Chromatography Mass Spectrometry ◽  
Extracellular Polysaccharides ◽  
Confocal Laser

AbstractStreptococcus mutans (S. mutans) is generally regarded as a major contributor to dental caries because of its ability to synthesize extracellular polysaccharides (EPS) that aid in the formation of plaque biofilm. The VicRKX system of S. mutans plays an important role in biofilm formation. The aim of this study was to investigate the effects of vicK gene on specific characteristics of EPS in S. mutans biofilm. We constructed single-species biofilms formed by different mutants of vicK gene. Production and distribution of EPS were detected through atomic force microscopy, scanning electron microscopy and confocal laser scanning microscopy. Microcosmic structures of EPS were analyzed by gel permeation chromatography and gas chromatography-mass spectrometry. Cariogenicity of the vicK mutant was assessed in a specific pathogen-free rat model. Transcriptional levels of cariogenicity-associated genes were confirmed by quantitative real-time polymerase chain reaction. The results showed that deletion of vicK gene suppressed biofilm formation as well as EPS production, and EPS were synthesized mostly around the cells. Molecular weight and monosaccharide components underwent evident alterations. Biofilms formed in vivo were sparse and contributed a decreased degree of caries. Moreover, expressional levels of genes related to EPS synthesis were down-regulated, except for gtfB. Our report demonstrates that vicK gene enhances biofilm formation and subsequent caries development. And this may due to its regulations on EPS metabolism, like synthesis or microcosmic features of EPS. This study suggests that vicK gene and EPS can be considered as promising targets to modulate dental caries.

scholarly journals Effects of RelA on Key Virulence Properties of Planktonic and Biofilm Populations of Streptococcus mutans

2004 ◽  
Vol 72 (3) ◽  
pp. 1431-1440 ◽  
Author(s):  
José A. C. Lemos ◽  
Thomas A. Brown ◽  
Robert A. Burne
Keyword(s):  
Streptococcus Mutans ◽  
Biofilm Formation ◽  
Type Strain ◽  
Wild Type Strain ◽  
Stringent Response ◽  
Strain Differences ◽  
Acid Tolerance ◽  
Normal Growth ◽  
Wild Type ◽  
Carbohydrate Source

ABSTRACT Streptococcus mutans is a biofilm-forming bacterium that is adapted to tolerate rapid and dramatic fluctuations in nutrient availability, carbohydrate source, and pH in its natural environment, the human oral cavity. Dissecting the pathways used to form stable biofilms and to tolerate environmental stress is central to understanding the virulence of this organism. Here, we investigated the role of the S. mutans relA gene, which codes for a guanosine tetraphosphate and guanosine pentaphosphate [(p)ppGpp] synthetase/hydrolase, in biofilm formation and acid tolerance. Two mutants in which relA was insertionally inactivated or replaced by an antibiotic resistance determinant were constructed. Under normal growth and stress conditions, the mutants grew slower than the wild-type strain, although the final yields were similar. The mutants, which were still able to accumulate (p)ppGpp after the induction of a stringent response, showed significant reductions in biofilm formation on microtiter plates or hydroxylapatite disks. There was no difference in the sensitivities to acid killing of the parent and relA strains grown in planktonic cultures. However, when cells were grown in biofilms, the mutants became more acid resistant and could lower the pH through glycolysis faster and to a greater extent than the wild-type strain. Differences in acid resistance were not correlated with increases in F-ATPase activity, although bacterial sugar:phosphotransferase activity was elevated in the mutants. Expression of the luxS gene was increased as much as fivefold in the relA mutants, suggesting a link between AI-2 quorum sensing and the stringent response.

scholarly journals Influence of BrpA on Critical Virulence Attributes of Streptococcus mutans

2006 ◽  
Vol 188 (8) ◽  
pp. 2983-2992 ◽  
Author(s):  
Zezhang T. Wen ◽  
Henry V. Baker ◽  
Robert A. Burne
Keyword(s):  
Streptococcus Mutans ◽  
Biofilm Formation ◽  
Laser Scanning ◽  
Three Dimensional ◽  
Laser Scanning Microscopy ◽  
Tooth Surface ◽  
Confocal Laser ◽  
Carbohydrate Source ◽  
Flow Cells ◽  
Forming Characteristics

ABSTRACT Streptococcus mutans, the primary etiological agent of human dental caries, has developed multiple mechanisms to colonize and form biofilms on the tooth surface. The brpA gene codes for a predicted surface-associated protein with apparent roles in biofilm formation, autolysis, and cell division. In this study, we used two models to further characterize the biofilm-forming characteristics of a BrpA-deficient mutant, strain TW14. Compared to those of the parent strain, UA159, TW14 formed long chains and sparse microcolonies on hydroxylapatite disks but failed to accumulate and form three-dimensional biofilms when grown on glucose as the carbohydrate source. The biofilm formation defect was also readily apparent by confocal laser scanning microscopy when flow cells were used to grow biofilms. When subjected to acid killing at pH 2.8 for 45 min, the survival rate of strain TW14 was more than 1 log lower than that of the wild-type strain. TW14 was at least 3 logs more susceptible to killing by 0.2% hydrogen peroxide than was UA159. The expression of more than 200 genes was found by microarray analysis to be altered in cells lacking BrpA (P < 0.01). These results suggest that the loss of BrpA can dramatically influence the transcriptome and significantly affects the regulation of acid and oxidative stress tolerance and biofilm formation in S. mutans, which are key virulence attributes of the organism.

scholarly journals Comparison of Cariogenic Characteristics between Fluoride-sensitive and Fluoride-resistant Streptococcus mutans

2020 ◽  
Vol 47 (4) ◽  
pp. 397-405
Author(s):  
Seung-Hwan Ong ◽  
Jongsoo Kim ◽  
Dong-Heon Baek ◽  
Seunghoon Yoo
Keyword(s):  
Streptococcus Mutans ◽  
Biofilm Formation ◽  
Laser Scanning ◽  
Single Species ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Rt Pcr ◽  
Oral Biofilm ◽  
Low Levels ◽  
Number Of Bacteria

The aim of this study is to compare cariogenic characteristics of fluoride-sensitive <i>Streptococcus mutans</i> [fluoride-sensitive (FS) <i>S. mutans</i> ] and fluoride-resistant <i>Streptococcus mutans</i> [fluoride-resistant (FR) <i>S. mutans</i>] in the presence of sucrose, and to evaluate its effect on cariogenic biofilm formation. <i>S. mutans</i> ATCC 25175 was continuously cultured in trypticase soy broth (TSB) containing NaF (70 ppm) for 40 days to generate FR <i>S. mutans</i> . FS and FR <i>S. mutans</i> were inoculated in TSB with or without 2% sucrose, and optical density and pH were measured every hour. An oral biofilm was formed using saliva bacteria and analyzed through confocal laser scanning microscopy and CFU count. Finally, the expression of glucosyltransferases genes of both <i>S. mutans</i> was investigated through RT-PCR. FR <i>S. mutans</i> exhibited slower growth and lower acidogenicity in the presence of sucrose compared to FS <i>S. mutans</i> . Both cariogenic and single species biofilm formation was lower in the presence of FR <i>S. mutans</i> , along with reduced number of bacteria. FR <i>S. mutans</i> showed significantly low levels of gtfB, gtfC, and gtfD expression compared to FS <i>S. mutans</i> . On the basis of results, FR <i>S. mutans</i> may be less virulent in the induction of dental caries.

The role of divalent ions in cariogenic biofilm formation

2020 ◽  
Author(s):  
Monika Astasov-Frauenhoffer ◽  
Elena Steiger ◽  
Julia Muelli ◽  
Olivier Braissant ◽  
Tuomas Waltimo
Keyword(s):  
Biofilm Formation ◽  
Type Strain ◽  
Laser Scanning ◽  
Laser Scanning Microscopy ◽  
Titration Calorimetry ◽  
Confocal Laser ◽  
Calcium Magnesium ◽  
Calcium And Magnesium ◽  
Cariogenic Biofilm

&lt;p&gt;The aim of the study was to investigate the effect of calcium, magnesium, and zinc on cariogenic biofilm formation and their interaction with bacterial EPS. This was evaluated using two &lt;em&gt;S. mutans&lt;/em&gt; strains and different carbohydrates (glucose, sucrose and fructose).&lt;/p&gt; &lt;p&gt;Different combinations of carbohydrates and ions were investigated for their effect on the biofilm formation on hydroxyapatite disks by confocal laser scanning microscopy. Moreover, exopolysaccharides were purified and their affinity to the ions was measured by isothermal titration calorimetry.&lt;/p&gt; &lt;p&gt;The biofilm formation of &lt;em&gt;S. mutans &lt;/em&gt;clinical isolate was almost eliminated in the presence of Zn&lt;sup&gt;2+&lt;/sup&gt; and promoted by Ca&lt;sup&gt;2+&lt;/sup&gt;, while adhesion seems to be more inhibited by Ca&lt;sup&gt;2+&lt;/sup&gt; and Mg&lt;sup&gt;2+&lt;/sup&gt; for &lt;em&gt;S. mutans&lt;/em&gt; type strain. The EPS of cilincal isolate had a higher binding affinity towards calcium and magnesium than the type strain.&lt;/p&gt; &lt;p&gt;There seems to be a fine balance between these ions that needs to be maintained as excessive concentrations of one or another destroy the balance between the three.&lt;/p&gt;

scholarly journals Physiologic Effects of Forced Down-Regulation of dnaK and groEL Expression in Streptococcus mutans

2006 ◽  
Vol 189 (5) ◽  
pp. 1582-1588 ◽  
Author(s):  
José A. Lemos ◽  
Yaima Luzardo ◽  
Robert A. Burne
Keyword(s):  
Streptococcus Mutans ◽  
Biofilm Formation ◽  
Parent Strain ◽  
Type Strain ◽  
Wild Type Strain ◽  
Acid Tolerance ◽  
Low Ph ◽  
Broth Culture ◽  
Wild Type ◽  
Compensatory Mutations

ABSTRACT Strains of Streptococcus mutans lacking DnaK or GroEL appear not to be isolable. To better distinguish the roles played by these chaperones/chaperonins in the physiology of S. mutans, we created a knockdown strategy to lower the levels of DnaK by over 95% in strain SM12 and the level of GroEL about 80% in strain SM13. Interestingly, GroEL levels were approximately twofold higher in SM12 than in the parent strain, but the levels of DnaK were not altered in the GroEL knockdown strain. Both SM12 and SM13 grew slower than the parent strain, had a strong tendency to aggregate in broth culture, and showed major changes in their proteomes. Compared with the wild-type strain, SM12 and SM13 had impaired biofilm-forming capacities when grown in the presence of glucose. The SM12 strain was impaired in its capacity to grow at 44°C or at pH 5.0 and was more susceptible to H2O2, whereas SM13 behaved like the wild-type strain under these conditions. Phenotypical reversions were noted for both mutants when cells were grown in continuous culture at a low pH, suggesting the occurrence of compensatory mutations. These results demonstrate that DnaK and GroEL differentially affect the expression of key virulence traits, including biofilm formation and acid tolerance, and support that these chaperones have evolved to accommodate unique roles in the context of this organism and its niche.

scholarly journals AtlA Mediates Extracellular DNA Release, Which Contributes to Streptococcus mutans Biofilm Formation in an Experimental Rat Model of Infective Endocarditis

2017 ◽  
Vol 85 (9) ◽  
Author(s):  
Chiau-Jing Jung ◽  
Ron-Bin Hsu ◽  
Chia-Tung Shun ◽  
Chih-Chieh Hsu ◽  
Jean-San Chia
Keyword(s):  
Infective Endocarditis ◽  
Streptococcus Mutans ◽  
Mutant Strain ◽  
Rat Model ◽  
Calcium Ions ◽  
Biofilm Formation ◽  
Laser Scanning Microscopy ◽  
Extracellular Dna ◽  
Wild Type ◽  
Content Type

ABSTRACT Host factors, such as platelets, have been shown to enhance biofilm formation by oral commensal streptococci, inducing infective endocarditis (IE), but how bacterial components contribute to biofilm formation in vivo is still not clear. We demonstrated previously that an isogenic mutant strain of Streptococcus mutans deficient in autolysin AtlA (ΔatlA) showed a reduced ability to cause vegetation in a rat model of bacterial endocarditis. However, the role of AtlA in bacterial biofilm formation is unclear. In this study, confocal laser scanning microscopy analysis showed that extracellular DNA (eDNA) was embedded in S. mutans GS5 floes during biofilm formation on damaged heart valves, but an ΔatlA strain could not form bacterial aggregates. Semiquantification of eDNA by PCR with bacterial 16S rRNA primers demonstrated that the ΔatlA mutant strain produced dramatically less eDNA than the wild type. Similar results were observed with in vitro biofilm models. The addition of polyanethol sulfonate, a chemical lysis inhibitor, revealed that eDNA release mediated by bacterial cell lysis is required for biofilm initiation and maturation in the wild-type strain. Supplementation of cultures with calcium ions reduced wild-type growth but increased eDNA release and biofilm mass. The effect of calcium ions on biofilm formation was abolished in ΔatlA cultures and by the addition of polyanethol sulfonate. The VicK sensor, but not CiaH, was found to be required for the induction of eDNA release or the stimulation of biofilm formation by calcium ions. These data suggest that calcium ion-regulated AtlA maturation mediates the release of eDNA by S. mutans, which contributes to biofilm formation in infective endocarditis.

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