Mechanism of action of essential oils extracted from bamboo (Phyllostachys heterocycla cv. pubescens) leaves: Chemical composition and antimicrobial activity against four food-related microorganisms

Abstract

The antimicrobial activities and potential mechanisms of natural essential oils (EOs) derived from the leaves of Phyllostachys heterocycla cv. pubescens (bamboo) against a broad range of food-borne pathogens, which included Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria and yeast (Saccharomyces cerevisiae), were investigated. The chemical characterization of bamboo leaf essential oils (BLEOs) was determined by gas chromatography-mass spectrometry (GC-MS). Hexadecanoic acid (19.35%) and phytol (10.54%), the antimicrobial ingredients that have been reported in previous studies, were found to be the major components in the BLEOs. According to the antimicrobial tests, Escherichia coli was most sensitive to BLEOs, showing the largest DIZ (12.77 ± 0.25 mm) and the lowest MIC (0.56 mg/mL). In addition, the pathogen growth in the presence of BLEOs at two-times the minimum inhibitory concentration (MIC) revealed that the EOs were bacteriostatic after 12 h to all tested strains. According to the results from the cellular constituents, the fatty acids profiles, and the atomic force microscope (AFM) observations, the membranes of the treated cells were severely damaged. Therefore, it was concluded that the mechanism of action of BLEOs could be described as a disruption to the pathogen’s membrane integrity. The results indicated that the EOs from the leaves of bamboo could be a potential source of antimicrobial agents in the future.