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Antibacterial activity of phenethyl alcohol and resulting membrane alterations
J Corre1, J J Lucchini, G M Mercier
1Laboratoire de Microbiologie, Hygiène Microbienne, Immunologie, Faculté de Pharmacie, Marseille, France.
Abstract:
The antibacterial activity of phenethyl alcohol (PEA) towards Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive bacteria (Staphylococcus aureus and Enterococcus faecium) was investigated. This activity was expressed as IC (inhibitory concentration) and BC (bactericidal concentration). PEA was bactericidal in the concentration range of 90 to 180 mM, these concentrations being 4- to 5-fold higher than the corresponding IC. The mechanism of action of PEA upon the cell membrane of bacteria was also studied. Morphological examination with a transmission electron microscope showed that Gram-negative cell envelopes were permeabilized; for Gram-positive bacteria, the plasmic membrane in S. aureus was solubilized, whereas lesser changes were observed in E. faecium. At lethal concentrations, PEA also induced a rapid and total leakage of K+ ions from the four strains studied. Despite the correlation between alterations in the structural integrity of the cytoplasmic membrane in Gram-negative cells and the loss of cell viability, it cannot be inferred that membrane damage is the only cause of the lethal effect.
Insights
Phenethyl alcohol (PEA) shows antibacterial activity, acting as a bactericide at higher concentrations. It disrupts bacterial cell membranes, causing potassium leakage and cell death, though membrane damage isn't the sole lethal factor.
Area of Science:
- Microbiology
- Biochemistry
Background:
- Phenethyl alcohol (PEA) is a known antimicrobial agent.
- Understanding its precise mechanism against various bacterial strains is crucial for its application.
Purpose of the Study:
- To investigate the antibacterial activity of phenethyl alcohol (PEA) against Gram-negative and Gram-positive bacteria.
- To elucidate the mechanism of action of PEA on bacterial cell membranes.
Main Methods:
- Determined inhibitory concentration (IC) and bactericidal concentration (BC) of PEA.
- Utilized transmission electron microscopy (TEM) for morphological analysis.
- Measured potassium (K+) ion leakage from bacterial cells.
Main Results:
- PEA exhibited bactericidal activity at 90-180 mM, 4-5 times higher than IC.
- TEM revealed permeabilization of Gram-negative cell envelopes and solubilization of S. aureus cytoplasmic membrane.
- Lethal PEA concentrations caused rapid, total K+ ion leakage in all tested strains.
Conclusions:
- PEA demonstrates significant antibacterial and bactericidal effects against both Gram-negative and Gram-positive bacteria.
- PEA's mechanism involves disruption of bacterial cell membrane integrity and ion leakage.
- While membrane damage correlates with lethality, it may not be the exclusive cause of cell death.