Superior antibacterial activity of nanoemulsion of Thymus daenensis essential oil against E. coli. (1st March 2016)

• Record Type: Journal Article
• Authors: Moghimi, Roya; Ghaderi, Lida; Rafati, Hasan; Aliahmadi, Atousa; McClements, David Julian
• Is Part Of: Food chemistry. Volume 194(2016)
• Page Start: 410
• Page End: 415
• Publication Date: 2016-03-01
• Subjects: Tween 80 (Pubchem CID: 52811955) -- Span 80 (Pubchem CID: 5385498) -- Glutaraldehyde (Pubchem CID: 3485); Natural antimicrobial -- Mechanism of action -- Membrane integrity -- Ostwald ripening -- Particle diameter; Food -- Analysis -- Periodicals; Food -- Composition -- Periodicals; 664
• DOI: 10.1016/j.foodchem.2015.07.139
• Languages: English
• ISSNs: 0308-8146

Abstract

Highlights: Nanoemulsions of Thymus daenensis essential oil (diameter ∼150 nm) were prepared. The selected nanoemulsion was stable at least for six months. The antibacterial activity of the nanoemulsion against E. coli considerably improved. Cell constituents leakage increased in the nanoemulsion treated bacterium. The nanoemulsion killed all the bacteria in about 5 min. Abstract: Natural preservatives are being extensively investigated for their potential industrial applications in foods and other products. In this work, an essential oil ( Thymus daenensis ) was formulated as a water-dispersible nanoemulsion (diameter = 143 nm) using high-intensity ultrasound. The antibacterial activity of the essential oil in both pure and nanoemulsion forms was measured against an important food-borne pathogen bacterium, Escherichia coli . Antibacterial activity was determined by measuring the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The antibacterial activity of the essential oil against E. coli was enhanced considerably when it was converted into a nanoemulsion, which was attributed to easier access of the essential oils to the bacterial cells. The mechanism of antibacterial activity was investigated by measuring potassium, protein, and nucleic acid leakage from the cells, and electron microscopy. Evaluation of the kinetics of microbial deactivation showed that the nanoemulsion killed all the bacteria in about 5 min, whereas only a 1-log reduction was observed for pure essential oil. The nanoemulsion appeared to amplify the antibacterial activity of essential oils against E. coli by increasing their ability to disrupt cell membrane integrity.