University of Isfahan Journal of Microbial Biology 3060-7647 13 52 2024 11 20 Nanoemulsification of Zataria multiflora essential oil and its antibacterial and anti-biofilm activity against foodborne pathogen Salmonella typhimurium Nanoemulsification of Zataria multiflora essential oil and its antibacterial and anti-biofilm activity against foodborne pathogen Salmonella typhimurium 63 74 28803 10.22108/bjm.2024.142264.1603 FA Bahare Asgari Department of Microbiology, Faculty of Biological Sciences, Alzahra University, Tehran, Iran Ali Mohammadi Department of Microbiology, Faculty of Biological Sciences, Alzahra University, Tehran, Iran Bahare Attaran Department of Microbiology, Faculty of Biological Sciences, Alzahra University, Tehran, Iran Journal Article 2024 07 27 Although Zataria multiflora essential oil (ZEO) has good antimicrobial properties like other EOs, it cannot be used in food systems and commercial products due to its high volatility and low water solubility, and its bioactive compounds can be easily degraded under the influence of environmental factors. In this case, their nanoemulsification may be an efficient and practical approach to overcome this problem. In addition, such delivery systems can improve the stability, bioactivity and quality properties of antimicrobial EOs in food systems. The optimized formulation, prepared using a low energy production method, containing 4% w/w ZEO and 12% w/w mixed surfactant (SDS+Tween 80), produced a transparent and stable nanoemulsion for 90 days with a mean particle diameter of 120.1 nm. The antibacterial activity of pure ZEO (PZEO) and its nanoemulsions (ZEON) against the tested strain was evaluated using solid diﬀusion, vapour phase and broth assays. Minimum inhibitory concentration (MIC) and bacteriostatic concentration (MBC), dynamic time-kill, anti-biofilm activity and morphological changes in Salmonella were determined. The strong antibacterial activity of PZEO and ZEON was demonstrated with MIC values of 2000 ppm and 4000 ppm, respectively. The killing kinetics study showed that there was a rapid and widespread decrease in CFU during the first 15 min of exposure to ZEON at MIC concentration. In addition, ZEON had significant anti-biofilm activity , reducing 82% of the one-day-old bioﬁlm of S. typhimurium at the MIC concentration. The SEM micrographs taken at MIC showed signiﬁcant morphological damage in the ZEON treated bacterial cells and no viability. The data presented, taking into account the optimal performance of antimicrobials against foodborne pathogens, can help in the rational design of delivery systems based on nanoemulsion of essential oils in the food industry. Although Zataria multiflora essential oil (ZEO) has good antimicrobial properties like other EOs, it cannot be used in food systems and commercial products due to its high volatility and low water solubility, and its bioactive compounds can be easily degraded under the influence of environmental factors. In this case, their nanoemulsification may be an efficient and practical approach to overcome this problem. In addition, such delivery systems can improve the stability, bioactivity and quality properties of antimicrobial EOs in food systems. The optimized formulation, prepared using a low energy production method, containing 4% w/w ZEO and 12% w/w mixed surfactant (SDS+Tween 80), produced a transparent and stable nanoemulsion for 90 days with a mean particle diameter of 120.1 nm. The antibacterial activity of pure ZEO (PZEO) and its nanoemulsions (ZEON) against the tested strain was evaluated using solid diﬀusion, vapour phase and broth assays. Minimum inhibitory concentration (MIC) and bacteriostatic concentration (MBC), dynamic time-kill, anti-biofilm activity and morphological changes in Salmonella were determined. The strong antibacterial activity of PZEO and ZEON was demonstrated with MIC values of 2000 ppm and 4000 ppm, respectively. The killing kinetics study showed that there was a rapid and widespread decrease in CFU during the first 15 min of exposure to ZEON at MIC concentration. In addition, ZEON had significant anti-biofilm activity , reducing 82% of the one-day-old bioﬁlm of S. typhimurium at the MIC concentration. The SEM micrographs taken at MIC showed signiﬁcant morphological damage in the ZEON treated bacterial cells and no viability. The data presented, taking into account the optimal performance of antimicrobials against foodborne pathogens, can help in the rational design of delivery systems based on nanoemulsion of essential oils in the food industry.

https://bjm.ui.ac.ir/article_28803_314ec3bd836659e6b2d05ff6ea26251e.pdf