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Analyzing the antibacterial effects of food ingredients: model experiments with allicin and garlic extracts on biofilm formation and viability of Staphylococcus epidermidis.

Wu X, Santos RR, Fink-Gremmels J - Food Sci Nutr (2015)

Bottom Line: To demonstrate different effects of garlic extracts and their main antibiotic substance allicin, as a template for investigations on the antibacterial activity of food ingredients.Biofilm density was impaired significantly at a concentration of 0.78 μg/mL allicin.The current experimental protocol has proven to be a valid approach to characterize the antimicrobial activity of traditional food ingredients.

View Article: PubMed Central - PubMed

Affiliation: Division Veterinary Pharmacology, Pharmacotherapy and Toxicology, Faculty of Veterinary Medicine, Institute for Risk Assessment Sciences, Utrecht University Utrecht, The Netherlands.

ABSTRACT
To demonstrate different effects of garlic extracts and their main antibiotic substance allicin, as a template for investigations on the antibacterial activity of food ingredients. Staphylococcus epidermidis ATCC 12228 and the isogenic biofilm-forming strain ATCC 35984 were used to compare the activity of allicin against planktonic bacteria and bacterial biofilms. The minimal inhibitory concentration (MIC) and the minimum biofilm inhibitory concentration (MBIC) for pure allicin were identical and reached at a concentration of 12.5 μg/mL. MBICs for standardized garlic extracts were significantly lower, with 1.56 and 0.78 μg/mL allicin for garlic water and ethanol extract, respectively. Biofilm density was impaired significantly at a concentration of 0.78 μg/mL allicin. Viability staining followed by confocal laser scanning microscopy showed, however, a 100% bactericidal effect on biofilm-embedded bacteria at a concentration of 3.13 μg/mL allicin. qRT-PCR analysis provided no convincing evidence for specific effects of allicin on biofilm-associated genes. Extracts of fresh garlic are more potent inhibitors of Staphylococcus epidermidis biofilms than pure allicin, but allicin exerts a unique bactericidal effect on biofilm-embedded bacteria. The current experimental protocol has proven to be a valid approach to characterize the antimicrobial activity of traditional food ingredients.

No MeSH data available.


Related in: MedlinePlus

Minimum biofilm inhibitory concentration (MBIC) and viability of Staphylococcus epidermidis (ATCC 35984) within a biofilm exposed to different concentrations of allicin. (A) Results of the safranin staining method (% OD value at 540 nm wavelength, mean ± SEM). (B) Results of live/dead staining with SYTO® green and propidium iodide and quantitative evaluation with CLSM (mean ± SEM). Different letters (a–d) indicate significant (P < 0.0001) differences.
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fig03: Minimum biofilm inhibitory concentration (MBIC) and viability of Staphylococcus epidermidis (ATCC 35984) within a biofilm exposed to different concentrations of allicin. (A) Results of the safranin staining method (% OD value at 540 nm wavelength, mean ± SEM). (B) Results of live/dead staining with SYTO® green and propidium iodide and quantitative evaluation with CLSM (mean ± SEM). Different letters (a–d) indicate significant (P < 0.0001) differences.

Mentions: Staphylococcus epidermidis (ATCC 35984) was cultured in the presence of different concentrations of allicin for 24 h to determine the MBIC. The MBIC is defined as the concentration at which biofilm density is reduced by >90% when compared with OD values of controls (here at an OD value <0.06). Using this definition, it could be shown that the MBIC of allicin was 12.5 μg/mL, but biofilm formation was inhibited significantly already after exposure to 0.78 μg/mL allicin (Fig.3A). The percentage of viable bacteria in the biofilm showed a rapid and significant decrease (P < 0.0001) to 60% of controls already after exposure to 0.195 μg/mL allicin, and exposure to 3.13 μg/mL allicin resulted in a complete loss of viability (100%) of bacteria within the biofilm (Fig.3B).


Analyzing the antibacterial effects of food ingredients: model experiments with allicin and garlic extracts on biofilm formation and viability of Staphylococcus epidermidis.

Wu X, Santos RR, Fink-Gremmels J - Food Sci Nutr (2015)

Minimum biofilm inhibitory concentration (MBIC) and viability of Staphylococcus epidermidis (ATCC 35984) within a biofilm exposed to different concentrations of allicin. (A) Results of the safranin staining method (% OD value at 540 nm wavelength, mean ± SEM). (B) Results of live/dead staining with SYTO® green and propidium iodide and quantitative evaluation with CLSM (mean ± SEM). Different letters (a–d) indicate significant (P < 0.0001) differences.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4376410&req=5

fig03: Minimum biofilm inhibitory concentration (MBIC) and viability of Staphylococcus epidermidis (ATCC 35984) within a biofilm exposed to different concentrations of allicin. (A) Results of the safranin staining method (% OD value at 540 nm wavelength, mean ± SEM). (B) Results of live/dead staining with SYTO® green and propidium iodide and quantitative evaluation with CLSM (mean ± SEM). Different letters (a–d) indicate significant (P < 0.0001) differences.
Mentions: Staphylococcus epidermidis (ATCC 35984) was cultured in the presence of different concentrations of allicin for 24 h to determine the MBIC. The MBIC is defined as the concentration at which biofilm density is reduced by >90% when compared with OD values of controls (here at an OD value <0.06). Using this definition, it could be shown that the MBIC of allicin was 12.5 μg/mL, but biofilm formation was inhibited significantly already after exposure to 0.78 μg/mL allicin (Fig.3A). The percentage of viable bacteria in the biofilm showed a rapid and significant decrease (P < 0.0001) to 60% of controls already after exposure to 0.195 μg/mL allicin, and exposure to 3.13 μg/mL allicin resulted in a complete loss of viability (100%) of bacteria within the biofilm (Fig.3B).

Bottom Line: To demonstrate different effects of garlic extracts and their main antibiotic substance allicin, as a template for investigations on the antibacterial activity of food ingredients.Biofilm density was impaired significantly at a concentration of 0.78 μg/mL allicin.The current experimental protocol has proven to be a valid approach to characterize the antimicrobial activity of traditional food ingredients.

View Article: PubMed Central - PubMed

Affiliation: Division Veterinary Pharmacology, Pharmacotherapy and Toxicology, Faculty of Veterinary Medicine, Institute for Risk Assessment Sciences, Utrecht University Utrecht, The Netherlands.

ABSTRACT
To demonstrate different effects of garlic extracts and their main antibiotic substance allicin, as a template for investigations on the antibacterial activity of food ingredients. Staphylococcus epidermidis ATCC 12228 and the isogenic biofilm-forming strain ATCC 35984 were used to compare the activity of allicin against planktonic bacteria and bacterial biofilms. The minimal inhibitory concentration (MIC) and the minimum biofilm inhibitory concentration (MBIC) for pure allicin were identical and reached at a concentration of 12.5 μg/mL. MBICs for standardized garlic extracts were significantly lower, with 1.56 and 0.78 μg/mL allicin for garlic water and ethanol extract, respectively. Biofilm density was impaired significantly at a concentration of 0.78 μg/mL allicin. Viability staining followed by confocal laser scanning microscopy showed, however, a 100% bactericidal effect on biofilm-embedded bacteria at a concentration of 3.13 μg/mL allicin. qRT-PCR analysis provided no convincing evidence for specific effects of allicin on biofilm-associated genes. Extracts of fresh garlic are more potent inhibitors of Staphylococcus epidermidis biofilms than pure allicin, but allicin exerts a unique bactericidal effect on biofilm-embedded bacteria. The current experimental protocol has proven to be a valid approach to characterize the antimicrobial activity of traditional food ingredients.

No MeSH data available.


Related in: MedlinePlus