The antimicrobial effect of orange, lemon and bergamot esential oils against Enterococcus sp
type: CreativeWork
description: Citrus essential oils (EO) are potential antimicrobials, first described as such in 1949 by Piacentini. Due to their acceptability in terms of fragrance and flavour characteristics, they lend themselves to use both in food and in clinical practice. Lemon (Citrus limon) or sweet orange (Citrus sinensis) or bergamot (Citrus bergamia) essential oils and their components (limonene, linalool, citral, hersipidin and neoericitrin) and vapours at different temperatures and pHs were tested for their anti-microbial activity against vancomycin-sensitive Enterococcus faecium and Enterococcus faecalis. Lemon essential oil alone or blended and orange EO alone were not as effective as citral or linalool alone or bergamot blends with inhibition diameters of > 9cm. The ranges established for differences in inhibition of growth were; 5-15°C, 20-25°C, 30-45°C and 50°C (p ≤ 0.005) and pHs 4.5-6.5, pH 7.5, and pHs 8.5 —10.5 (p ≤ 0.001). A blend of 1:1 (v/v) orange/bergamot EO was the most effective with MICs at 25°C and pH 5.5 of 0.25% - 0.5% (v/v) and an MID of 50mg/i at 50°C at pH 7.5, under these conditions viable counts were reduced by 5.5 - 10 log10 cfu/ml (p ≤ 0.001). The mechanisms by which a blend of orange/bergamot EO and its vapour bring about their antimicrobial effect were assessed. Transmission electron microscope (TEM) images established morphological changes as well as suggesting EO blend uptake into the cell. The permeability of the cell increased by x2 after being subjected to the EO and by x40 after exposure to the vapour. There were decreases of 1.5 in intracellular pH, 20 a.u. in membrane potential and 18 pmol/mg protein of intracellular ATP. The application of the EO blend impregnated into wipes reduced surface microbial load of vancomycin resistant and vancomycin susceptible E. faecium and E. faecalis by up to 4 log10 compared with control wipes (p ≤ 0.00 1). The use of the EO blend vapour on surfaces resulted in a 2.5 log10 reduction over 24 hours, whilst the vapo…
abstract: Citrus essential oils (EO) are potential antimicrobials, first described as such in 1949 by Piacentini. Due to their acceptability in terms of fragrance and flavour characteristics, they lend themselves to use both in food and in clinical practice. Lemon (Citrus limon) or sweet orange (Citrus sinensis) or bergamot (Citrus bergamia) essential oils and their components (limonene, linalool, citral, hersipidin and neoericitrin) and vapours at different temperatures and pHs were tested for their anti-microbial activity against vancomycin-sensitive Enterococcus faecium and Enterococcus faecalis. Lemon essential oil alone or blended and orange EO alone were not as effective as citral or linalool alone or bergamot blends with inhibition diameters of > 9cm. The ranges established for differences in inhibition of growth were; 5-15°C, 20-25°C, 30-45°C and 50°C (p ≤ 0.005) and pHs 4.5-6.5, pH 7.5, and pHs 8.5 —10.5 (p ≤ 0.001). A blend of 1:1 (v/v) orange/bergamot EO was the most effective with MICs at 25°C and pH 5.5 of 0.25% - 0.5% (v/v) and an MID of 50mg/i at 50°C at pH 7.5, under these conditions viable counts were reduced by 5.5 - 10 log10 cfu/ml (p ≤ 0.001). The mechanisms by which a blend of orange/bergamot EO and its vapour bring about their antimicrobial effect were assessed. Transmission electron microscope (TEM) images established morphological changes as well as suggesting EO blend uptake into the cell. The permeability of the cell increased by x2 after being subjected to the EO and by x40 after exposure to the vapour. There were decreases of 1.5 in intracellular pH, 20 a.u. in membrane potential and 18 pmol/mg protein of intracellular ATP. The application of the EO blend impregnated into wipes reduced surface microbial load of vancomycin resistant and vancomycin susceptible E. faecium and E. faecalis by up to 4 log10 compared with control wipes (p ≤ 0.00 1). The use of the EO blend vapour on surfaces resulted in a 2.5 log10 reduction over 24 hours, whilst the vapo…
author: Fisher, Katie
language: eng
date published: 2008
date modified: 2026-07-24T03:26:39Z
provider: University of Northampton
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Northampton