The Antimicrobial Effect of Melissa officinalis L. Essential Oil on Vibrio parahaemolyticus: Insights Based on the Cell Membrane and External Structure

Abstract

The study was to evaluate the antimicrobial impacts on Melissa officinalis L. essential oil (MOEO) against Vibrio parahaemolyticus. The minimum inhibitory concentration (MIC) of MOEO on Vibrio parahaemolyticus was 1 μL⋅mL–1. The kill-time curve exhibited that MOEO had good antimicrobial activity. The analysis of cellular ingredients leakage and cell viability illustrated that MOEO has destruction to the morphology of the cell membrane. The damage to the membrane integrity by MOEO has been confirmed by transmission and scanning electron microscopy, obvious morphological and ultrastructural changes were observed in the treated bacterial cells. The MOEO at 0.5 μL⋅mL–1 can inhibit the biofilm formation, biofilm motility, and extracellular polysaccharide production. Meanwhile, the qPCR results exhibited MOEO inhibited the expression of virulence genes. The findings showed that MOEO exerted its antimicrobial effect mainly by destroying the membrane, which indicated its potential as a natural food preservative.

The antimicrobial effect of Melissa officinalis L. essential oil to Shewanella putrefaciens: Insights based on the cell membrane and biofilm

“…Citronella has excellent antibacterial properties (Miraj, Rafieian‐Kopaei & Kiani, 2017). The results were similar with Yu et al (2022) who found MOEO composed of geranial, neral, citronellal, and aldehydes. Besides, Miraj et al, (2017) said oxygen‐containing monoterpenes such as citral isomers, geranial, and citronellal were the antimicrobial ingredients, and citronellal and geranial had been reported to be the reason for the antimicrobial effect of MOEO (Yu et al, 2022).…”

“…The minimum inhibitory concentration (MIC) of MOEO on S . putrefaciens was measured by the method of broth microdilution (Yu, Pei, Qiu, Mei, & Xie, 2022). A total of 100 μl initial suspension was added to 96‐well plate containing 100 μl of different concentrations of MOEO, and the final concentrations of MOEO were 0.125–256 μl/ml.…”

“…The effect of MOEO on biofilms was determined with the method of violet staining (Yu et al, 2022). The overnight culture of S. putrefacien was collected with centrifuge at 8,000 × g at 4°C for 5 min and resuspended in TSB broth.…”

“…The initial suspension was mixed with different final concentrations of MOEO (0.25 and 0.5 μl/ml). The mixed suspensions were cultured at 30°C for 6 h. The effect of MOEO on EPS was determined with the method of Phenol‐Sulfuric Acid (Yu et al, 2022).…”

Antibiofilm effect and mechanism of protocatechuic aldehyde against Vibrio parahaemolyticus

“…The survival of V. parahaemolyticus under PCA inhibition was determined using a live/dead staining kit ( Yu et al, 2022 ). Briefly, the PCA (0 and 75 μg/mL)-treated bacterial suspension was centrifuged (6,000 × g for 5 min), then 10 μL of NucGreen and EthD-III mix was added, and left in the dark for 15 min.…”