title: Analyzing the antibacterial effects of food ingredients: model experiments with allicin and garlic extracts on biofilm formation and viability of Staphylococcus epidermidis.
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.
authors.affiliation: Division Veterinary Pharmacology, Pharmacotherapy and Toxicology, Faculty of Veterinary Medicine, Institute for Risk Assessment Sciences, Utrecht University Utrecht, The Netherlands.
authors.forename: Xueqing
authors.initials: X
authors.lastname: Wu
authors.affiliation: Division Veterinary Pharmacology, Pharmacotherapy and Toxicology, Faculty of Veterinary Medicine, Institute for Risk Assessment Sciences, Utrecht University Utrecht, The Netherlands.
authors.forename: Regiane R
authors.initials: RR
authors.lastname: Santos
authors.affiliation: Division Veterinary Pharmacology, Pharmacotherapy and Toxicology, Faculty of Veterinary Medicine, Institute for Risk Assessment Sciences, Utrecht University Utrecht, The Netherlands.
authors.forename: Johanna
authors.initials: J
authors.lastname: Fink-Gremmels
keywords: ATCC 12228; ATCC 35984; Allicin; Staphylococcus epidermidis; bacterial biofilm
references.citation: J Med Microbiol. 2007 Jan;56(Pt 1):83-93
references.pmid: 17172522
references.citation: J Agric Food Chem. 2004 Feb 25;52(4):682-7
references.pmid: 14969516
references.citation: Pol J Microbiol. 2013;62(3):243-51
references.pmid: 24459829
references.citation: Br J Biomed Sci. 2004;61(2):71-4
references.pmid: 15250668
references.citation: J Infect Dis. 2003 Sep 1;188(5):706-18
references.pmid: 12934187
references.citation: J Appl Microbiol. 2003;95(4):709-11
references.pmid: 12969283
references.citation: Molecules. 2014 Aug 19;19(8):12591-618
references.pmid: 25153873
references.citation: J Nutr. 2006 Mar;136(3 Suppl):716S-725S
references.pmid: 16484550
references.citation: Meat Sci. 2003 Jan;63(1):23-8
references.pmid: 22061980
references.citation: Antimicrob Agents Chemother. 2012 May;56(5):2314-25
references.pmid: 22314537
references.citation: Microbes Infect. 1999 Feb;1(2):125-9
references.pmid: 10594976
references.citation: Future Microbiol. 2010 Jun;5(6):917-33
references.pmid: 20521936
references.citation: Meat Sci. 2000 Jan;54(1):77-81
references.pmid: 22063715
references.citation: Food Chem. 2013 Dec 1;141(3):1655-60
references.pmid: 23870874
references.citation: Nat Rev Microbiol. 2007 Jan;5(1):48-56
references.pmid: 17143318
references.citation: BMC Microbiol. 2012 Jun 08;12:102
references.pmid: 22682058
references.citation: J Appl Microbiol. 2011 Mar;110(3):723-8
references.pmid: 21205098
references.citation: J Biol Chem. 2004 Sep 24;279(39):40927-37
references.pmid: 15263010
references.citation: J Vet Med B Infect Dis Vet Public Health. 2006 Sep;53(7):326-32
references.pmid: 16930277
references.citation: Int J Antimicrob Agents. 2013 Sep;42(3):195-201
references.pmid: 23796893
references.citation: ScientificWorldJournal. 2012;2012:561823
references.pmid: 22629145
references.citation: Clin Microbiol Infect. 2003 Feb;9(2):114-9
references.pmid: 12588331
references.citation: J Med Food. 2011 Nov;14(11):1338-43
references.pmid: 21548800
references.citation: Antioxid Redox Signal. 2011 Jul 1;15(1):123-33
references.pmid: 20712413
references.citation: J Bacteriol. 2001 Apr;183(8):2624-33
references.pmid: 11274123
references.citation: BMC Microbiol. 2012 May 17;12:76
references.pmid: 22594478
references.citation: J Microbiol Methods. 2014 Jun;101:63-6
references.pmid: 24726871
references.citation: J Med Microbiol. 2011 Jul;60(Pt 7):950-60
references.pmid: 21415203
references.citation: FEMS Immunol Med Microbiol. 2010 Aug;59(3):324-36
references.pmid: 20602635
references.citation: Biosci Biotechnol Biochem. 2009 Sep;73(9):1948-55
references.pmid: 19734685
references.citation: Mol Microbiol. 2005 Mar;55(6):1883-95
references.pmid: 15752207
references.citation: J Biol Chem. 1998 Jul 17;273(29):18586-93
references.pmid: 9660830