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Dynamics of Streptococcus mutans transcriptome in response to starch and sucrose during biofilm development.

Klein MI, DeBaz L, Agidi S, Lee H, Xie G, Lin AH, Hamaker BR, Lemos JA, Koo H - PLoS ONE (2010)

Bottom Line: Overall, the presence of sucrose and starch (suc+st) influenced the dynamics of S. mutans transcriptome (vs. sucrose alone), which may be associated with gradual digestion of starch by surface-adsorbed amylase.In contrast, at 30 h of biofilm development, multiple genes associated with sugar uptake/transport (e.g. maltose), two-component systems, fermentation/glycolysis and iron transport were differentially expressed in suc+st-biofilms (vs. sucrose-biofilms).Our data show complex remodeling of S. mutans-transcriptome in response to changing environmental conditions in situ, which could modulate the dynamics of biofilm development and pathogenicity.

View Article: PubMed Central - PubMed

Affiliation: Center for Oral Biology and Eastman Department of Dentistry, University of Rochester Medical Center, Rochester, New York, United States of America.

ABSTRACT
The combination of sucrose and starch in the presence of surface-adsorbed salivary α-amylase and bacterial glucosyltransferases increase the formation of a structurally and metabolically distinctive biofilm by Streptococcus mutans. This host-pathogen-diet interaction may modulate the formation of pathogenic biofilms related to dental caries disease. We conducted a comprehensive study to further investigate the influence of the dietary carbohydrates on S. mutans-transcriptome at distinct stages of biofilm development using whole genomic profiling with a new computational tool (MDV) for data mining. S. mutans UA159 biofilms were formed on amylase-active saliva coated hydroxyapatite discs in the presence of various concentrations of sucrose alone (ranging from 0.25 to 5% w/v) or in combination with starch (0.5 to 1% w/v). Overall, the presence of sucrose and starch (suc+st) influenced the dynamics of S. mutans transcriptome (vs. sucrose alone), which may be associated with gradual digestion of starch by surface-adsorbed amylase. At 21 h of biofilm formation, most of the differentially expressed genes were related to sugar metabolism, such as upregulation of genes involved in maltose/maltotriose uptake and glycogen synthesis. In addition, the groEL/groES chaperones were induced in the suc+st-biofilm, indicating that presence of starch hydrolysates may cause environmental stress. In contrast, at 30 h of biofilm development, multiple genes associated with sugar uptake/transport (e.g. maltose), two-component systems, fermentation/glycolysis and iron transport were differentially expressed in suc+st-biofilms (vs. sucrose-biofilms). Interestingly, lytT (bacteria autolysis) was upregulated, which was correlated with presence of extracellular DNA in the matrix of suc+st-biofilms. Specific genes related to carbohydrate uptake and glycogen metabolism were detected in suc+st-biofilms in more than one time point, indicating an association between presence of starch hydrolysates and intracellular polysaccharide storage. Our data show complex remodeling of S. mutans-transcriptome in response to changing environmental conditions in situ, which could modulate the dynamics of biofilm development and pathogenicity.

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RT-qPCR analysis of gtfB (A) and malE (B) genes expression.S. mutans growing in the presence of 0.5% sucrose, 0.5% sucrose +1% starch, and 1% sucrose at distinct time points of biofilms development process. The mRNA level of gtfB and malE in each sample was normalized to that of 16S rRNA. These values were then compared to those from 0.5% sucrose-grown biofilms (corresponding to an arbitrary value of 1) to determine the change (n-fold) in gene expression. Data are expressed as means ± standard deviations of triplicates from at least three separate experiments. Values marked with an asterisk are significantly different from the value for the 0.5% sucrose-grown biofilms (P<0.05, Tukey's test).
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pone-0013478-g001: RT-qPCR analysis of gtfB (A) and malE (B) genes expression.S. mutans growing in the presence of 0.5% sucrose, 0.5% sucrose +1% starch, and 1% sucrose at distinct time points of biofilms development process. The mRNA level of gtfB and malE in each sample was normalized to that of 16S rRNA. These values were then compared to those from 0.5% sucrose-grown biofilms (corresponding to an arbitrary value of 1) to determine the change (n-fold) in gene expression. Data are expressed as means ± standard deviations of triplicates from at least three separate experiments. Values marked with an asterisk are significantly different from the value for the 0.5% sucrose-grown biofilms (P<0.05, Tukey's test).

Mentions: Furthermore, we assessed the expression of genes gtfB and malE (associated with uptake of maltose, which is one of the main starch hydrolysates) by qRT-PCR at distinct stages of biofilm development under the selected carbohydrate sources. These genes were chosen because in our previous study we found that their expression was affected by the combination of sucrose plus starch [16], and are both relevant for biofilm formation (EPS-matrix synthesis) and physiology (intracellular sugar metabolism). A greater differential expression of these genes was observed among the experimental groups at 21, 24, 30 and 34 h of biofilms development (Fig. 1). This output also guided our selection of these 4 time-points for microarray experiments. The pH values of culture medium surrounding the biofilms from the different experimental groups were not significantly different from each other (6.67±0.03 at 21 h, 5.86±0.19 at 24 h, 4.63±0.01 at 30 h, and 4.83±0.03 at 34 h; P>0.05).


Dynamics of Streptococcus mutans transcriptome in response to starch and sucrose during biofilm development.

Klein MI, DeBaz L, Agidi S, Lee H, Xie G, Lin AH, Hamaker BR, Lemos JA, Koo H - PLoS ONE (2010)

RT-qPCR analysis of gtfB (A) and malE (B) genes expression.S. mutans growing in the presence of 0.5% sucrose, 0.5% sucrose +1% starch, and 1% sucrose at distinct time points of biofilms development process. The mRNA level of gtfB and malE in each sample was normalized to that of 16S rRNA. These values were then compared to those from 0.5% sucrose-grown biofilms (corresponding to an arbitrary value of 1) to determine the change (n-fold) in gene expression. Data are expressed as means ± standard deviations of triplicates from at least three separate experiments. Values marked with an asterisk are significantly different from the value for the 0.5% sucrose-grown biofilms (P<0.05, Tukey's test).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2957427&req=5

pone-0013478-g001: RT-qPCR analysis of gtfB (A) and malE (B) genes expression.S. mutans growing in the presence of 0.5% sucrose, 0.5% sucrose +1% starch, and 1% sucrose at distinct time points of biofilms development process. The mRNA level of gtfB and malE in each sample was normalized to that of 16S rRNA. These values were then compared to those from 0.5% sucrose-grown biofilms (corresponding to an arbitrary value of 1) to determine the change (n-fold) in gene expression. Data are expressed as means ± standard deviations of triplicates from at least three separate experiments. Values marked with an asterisk are significantly different from the value for the 0.5% sucrose-grown biofilms (P<0.05, Tukey's test).
Mentions: Furthermore, we assessed the expression of genes gtfB and malE (associated with uptake of maltose, which is one of the main starch hydrolysates) by qRT-PCR at distinct stages of biofilm development under the selected carbohydrate sources. These genes were chosen because in our previous study we found that their expression was affected by the combination of sucrose plus starch [16], and are both relevant for biofilm formation (EPS-matrix synthesis) and physiology (intracellular sugar metabolism). A greater differential expression of these genes was observed among the experimental groups at 21, 24, 30 and 34 h of biofilms development (Fig. 1). This output also guided our selection of these 4 time-points for microarray experiments. The pH values of culture medium surrounding the biofilms from the different experimental groups were not significantly different from each other (6.67±0.03 at 21 h, 5.86±0.19 at 24 h, 4.63±0.01 at 30 h, and 4.83±0.03 at 34 h; P>0.05).

Bottom Line: Overall, the presence of sucrose and starch (suc+st) influenced the dynamics of S. mutans transcriptome (vs. sucrose alone), which may be associated with gradual digestion of starch by surface-adsorbed amylase.In contrast, at 30 h of biofilm development, multiple genes associated with sugar uptake/transport (e.g. maltose), two-component systems, fermentation/glycolysis and iron transport were differentially expressed in suc+st-biofilms (vs. sucrose-biofilms).Our data show complex remodeling of S. mutans-transcriptome in response to changing environmental conditions in situ, which could modulate the dynamics of biofilm development and pathogenicity.

View Article: PubMed Central - PubMed

Affiliation: Center for Oral Biology and Eastman Department of Dentistry, University of Rochester Medical Center, Rochester, New York, United States of America.

ABSTRACT
The combination of sucrose and starch in the presence of surface-adsorbed salivary α-amylase and bacterial glucosyltransferases increase the formation of a structurally and metabolically distinctive biofilm by Streptococcus mutans. This host-pathogen-diet interaction may modulate the formation of pathogenic biofilms related to dental caries disease. We conducted a comprehensive study to further investigate the influence of the dietary carbohydrates on S. mutans-transcriptome at distinct stages of biofilm development using whole genomic profiling with a new computational tool (MDV) for data mining. S. mutans UA159 biofilms were formed on amylase-active saliva coated hydroxyapatite discs in the presence of various concentrations of sucrose alone (ranging from 0.25 to 5% w/v) or in combination with starch (0.5 to 1% w/v). Overall, the presence of sucrose and starch (suc+st) influenced the dynamics of S. mutans transcriptome (vs. sucrose alone), which may be associated with gradual digestion of starch by surface-adsorbed amylase. At 21 h of biofilm formation, most of the differentially expressed genes were related to sugar metabolism, such as upregulation of genes involved in maltose/maltotriose uptake and glycogen synthesis. In addition, the groEL/groES chaperones were induced in the suc+st-biofilm, indicating that presence of starch hydrolysates may cause environmental stress. In contrast, at 30 h of biofilm development, multiple genes associated with sugar uptake/transport (e.g. maltose), two-component systems, fermentation/glycolysis and iron transport were differentially expressed in suc+st-biofilms (vs. sucrose-biofilms). Interestingly, lytT (bacteria autolysis) was upregulated, which was correlated with presence of extracellular DNA in the matrix of suc+st-biofilms. Specific genes related to carbohydrate uptake and glycogen metabolism were detected in suc+st-biofilms in more than one time point, indicating an association between presence of starch hydrolysates and intracellular polysaccharide storage. Our data show complex remodeling of S. mutans-transcriptome in response to changing environmental conditions in situ, which could modulate the dynamics of biofilm development and pathogenicity.

Show MeSH
Related in: MedlinePlus