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Effects of mushroom and chicory extracts on the shape, physiology and proteome of the cariogenic bacterium Streptococcus mutans.

Signoretto C, Marchi A, Bertoncelli A, Burlacchini G, Milli A, Tessarolo F, Caola I, Papetti A, Pruzzo C, Zaura E, Lingström P, Ofek I, Spratt DA, Pratten J, Wilson M, Canepari P - BMC Complement Altern Med (2013)

Bottom Line: The best antimicrobial activity has been displayed by the LMM mushroom extract with a bacteriostatic effect.This report has shown an antibiotic-like mode of action of mushroom and chicory extracts as demonstrated by induced morphogenetic effects and inhibition of specific macromolecular synthesis.This feature as well as the safe use of this extract as result of its natural origin render the LMM both mushroom and chicory extracts suitable for the formulation into products for daily oral hygiene such as mouthwashes or toothpastes.

View Article: PubMed Central - HTML - PubMed

Affiliation: Dipartimento di Patologia e Diagnostica, Sezione di Microbiologia, Università di Verona, Verona, Italy. caterina.signoretto@univr.it

ABSTRACT

Background: Dental caries is an infectious disease which results from the acidic demineralisation of the tooth enamel and dentine as a consequence of the dental plaque (a microbial biofilm) accumulation. Research showed that several foods contain some components with antibacterial and antiplaque activity. Previous studies indicated antimicrobial and antiplaque activities in a low-molecular-mass (LMM) fraction of extracts from either an edible mushroom (Lentinus edodes) or from Italian red chicory (Cichorium intybus).

Methods: We have evaluated the antimicrobial mode of action of these fractions on Streptococcus mutans, the etiological agent of human dental caries. The effects on shape, macromolecular syntheses and cell proteome were analysed.

Results: The best antimicrobial activity has been displayed by the LMM mushroom extract with a bacteriostatic effect. At the MIC of both extracts DNA synthesis was the main macromolecular synthesis inhibited, RNA synthesis was less inhibited than that of DNA and protein synthesis was inhibited only by roughly 50%. The partial inhibition of protein synthesis is compatible with the observed significant increase in cell mass. The increase in these parameters is linked to the morphological alteration with transition from cocci of the untreated control to elongated cells. Interestingly, these modifications were also observed at sub-MIC concentrations. Finally, membrane and cytosol proteome analysis was conducted under LMM mushroom extract treatment in comparison with untreated S. mutans cells. Significant changes were observed for 31 membrane proteins and 20 of the cytosol fractions. The possible role of the changed proteins is discussed.

Conclusions: This report has shown an antibiotic-like mode of action of mushroom and chicory extracts as demonstrated by induced morphogenetic effects and inhibition of specific macromolecular synthesis. This feature as well as the safe use of this extract as result of its natural origin render the LMM both mushroom and chicory extracts suitable for the formulation into products for daily oral hygiene such as mouthwashes or toothpastes.

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Scanning electron microscopy of untreated S. mutans (column A) and after a three-hour treatment with 2x of LMM fraction of mushroom extract (column B) at different magnifications.
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Figure 2: Scanning electron microscopy of untreated S. mutans (column A) and after a three-hour treatment with 2x of LMM fraction of mushroom extract (column B) at different magnifications.

Mentions: Bacteria treated as above were also collected for morphological analysis by either optical and scanning electron microscopy. Preliminary observation by optical microscopy showed the presence of elongated cells as a result of the treatment. Thus, we resorted to SEM analysis in order to precisely evaluate cell size and distribution. Figure 2 shows the appearance of S. mutans during treatment with 2x LMM fraction of the mushroom extract. Elongated cells with interrupted septa were seen after a three-hour treatment, while untreated control cells presented the typical streptococcal appearance as ovoidal cells. Similar morphological changes were observed during treatment with the 6x chicory extract as well as with the above reported sub-inhibitory concentration of both mushroom and chicory (data not shown). Table 2 shows the mean cell length with additional parameters of the treated cells in comparison with the untreated ones. Measures confirmed the morphological changes at the inhibitory concentration, however it is worth of note that elongation has been observed also in cells treated with sub-inhibitory concentrations. Furthermore, analysis of the size distribution of untreated control S. mutans cells showed that the characteristic Gaussian bimodal distribution, i.e. just divided single cells and doubled cells prior of dividing, as previously reported for streptococci, was no longer evident in treated cells as a result of global cell elongation (Figure 3).


Effects of mushroom and chicory extracts on the shape, physiology and proteome of the cariogenic bacterium Streptococcus mutans.

Signoretto C, Marchi A, Bertoncelli A, Burlacchini G, Milli A, Tessarolo F, Caola I, Papetti A, Pruzzo C, Zaura E, Lingström P, Ofek I, Spratt DA, Pratten J, Wilson M, Canepari P - BMC Complement Altern Med (2013)

Scanning electron microscopy of untreated S. mutans (column A) and after a three-hour treatment with 2x of LMM fraction of mushroom extract (column B) at different magnifications.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3672068&req=5

Figure 2: Scanning electron microscopy of untreated S. mutans (column A) and after a three-hour treatment with 2x of LMM fraction of mushroom extract (column B) at different magnifications.
Mentions: Bacteria treated as above were also collected for morphological analysis by either optical and scanning electron microscopy. Preliminary observation by optical microscopy showed the presence of elongated cells as a result of the treatment. Thus, we resorted to SEM analysis in order to precisely evaluate cell size and distribution. Figure 2 shows the appearance of S. mutans during treatment with 2x LMM fraction of the mushroom extract. Elongated cells with interrupted septa were seen after a three-hour treatment, while untreated control cells presented the typical streptococcal appearance as ovoidal cells. Similar morphological changes were observed during treatment with the 6x chicory extract as well as with the above reported sub-inhibitory concentration of both mushroom and chicory (data not shown). Table 2 shows the mean cell length with additional parameters of the treated cells in comparison with the untreated ones. Measures confirmed the morphological changes at the inhibitory concentration, however it is worth of note that elongation has been observed also in cells treated with sub-inhibitory concentrations. Furthermore, analysis of the size distribution of untreated control S. mutans cells showed that the characteristic Gaussian bimodal distribution, i.e. just divided single cells and doubled cells prior of dividing, as previously reported for streptococci, was no longer evident in treated cells as a result of global cell elongation (Figure 3).

Bottom Line: The best antimicrobial activity has been displayed by the LMM mushroom extract with a bacteriostatic effect.This report has shown an antibiotic-like mode of action of mushroom and chicory extracts as demonstrated by induced morphogenetic effects and inhibition of specific macromolecular synthesis.This feature as well as the safe use of this extract as result of its natural origin render the LMM both mushroom and chicory extracts suitable for the formulation into products for daily oral hygiene such as mouthwashes or toothpastes.

View Article: PubMed Central - HTML - PubMed

Affiliation: Dipartimento di Patologia e Diagnostica, Sezione di Microbiologia, Università di Verona, Verona, Italy. caterina.signoretto@univr.it

ABSTRACT

Background: Dental caries is an infectious disease which results from the acidic demineralisation of the tooth enamel and dentine as a consequence of the dental plaque (a microbial biofilm) accumulation. Research showed that several foods contain some components with antibacterial and antiplaque activity. Previous studies indicated antimicrobial and antiplaque activities in a low-molecular-mass (LMM) fraction of extracts from either an edible mushroom (Lentinus edodes) or from Italian red chicory (Cichorium intybus).

Methods: We have evaluated the antimicrobial mode of action of these fractions on Streptococcus mutans, the etiological agent of human dental caries. The effects on shape, macromolecular syntheses and cell proteome were analysed.

Results: The best antimicrobial activity has been displayed by the LMM mushroom extract with a bacteriostatic effect. At the MIC of both extracts DNA synthesis was the main macromolecular synthesis inhibited, RNA synthesis was less inhibited than that of DNA and protein synthesis was inhibited only by roughly 50%. The partial inhibition of protein synthesis is compatible with the observed significant increase in cell mass. The increase in these parameters is linked to the morphological alteration with transition from cocci of the untreated control to elongated cells. Interestingly, these modifications were also observed at sub-MIC concentrations. Finally, membrane and cytosol proteome analysis was conducted under LMM mushroom extract treatment in comparison with untreated S. mutans cells. Significant changes were observed for 31 membrane proteins and 20 of the cytosol fractions. The possible role of the changed proteins is discussed.

Conclusions: This report has shown an antibiotic-like mode of action of mushroom and chicory extracts as demonstrated by induced morphogenetic effects and inhibition of specific macromolecular synthesis. This feature as well as the safe use of this extract as result of its natural origin render the LMM both mushroom and chicory extracts suitable for the formulation into products for daily oral hygiene such as mouthwashes or toothpastes.

Show MeSH
Related in: MedlinePlus