Antimicrobial activity of Thymus zygis essential oil against Listeria monocytogenes and its application as food preservative. (August 2022)

• Record Type: Journal Article
• Authors: Coimbra, Alexandra; Carvalho, Filomena; Duarte, Ana Paula; Ferreira, Susana
• Is Part Of: Innovative food science & emerging technologies. Volume 80(2022)
• Publication Date: 2022-08
• Subjects: Thymus zygis -- Listeria monocytogenes -- Antimicrobial activity -- Sanitizer -- Vegetables -- Milk -- Chicken; Food -- Biotechnology -- Periodicals; Food industry and trade -- Technological innovations -- Periodicals; Aliments -- Biotechnologie -- Périodiques; Food -- Biotechnology; Periodicals; Electronic journals; 664.005
• DOI: 10.1016/j.ifset.2022.103077
• Languages: English
• ISSNs: 1466-8564

Abstract

Abstract: Thymus zygis is an aromatic plant used in folk medicine. This work aimed to evaluate the anti- Listeria monocytogenes activity of T. zygis essential oil (EO), whose thymol is its major compound. Furthermore, the attenuation of this bacterium's virulence, namely by the inhibition of biofilm formation, motility and invasion of human cells, and the possible application of the EO in food were evaluated. The T. zygis EO showed antibacterial activity against L. monocytogenes with a minimum inhibitory concentration (MIC) of 0.05%, while showing a bactericidal effect. The EO significantly reduced the biofilm formation (inhibition from 16.85 to 89.86%) and motility (halos between 6.66 and 10.98 mm, compared to controls 13.12 to 17.22 mm), and not inducing cross-resistance to antibiotics, such as ampicillin, cefotaxime, erythromycin, gentamicin, tetracycline, and vancomycin. L. monocytogenes counts (initial inoculum of ~10 6 CFU/mL) were lowered by the use of 2× MIC of T. zygis EO in the chicken juice (1.53 log CFU/mL) and lettuce model (to below the detection limit) after two days of storage. The use of EO (0.2% (v/v)) for sanitizing fresh vegetables, reduce L. monocytogenes and natural microbiota for values below the detection limit of the method for iceberg lettuce after an immersion of 5 min. For the spinach, L. monocytogenes was reduced in 4.35 log CFU/mL and the natural microbiota was diminished in a range of 4.47 to 5.94 log CFU/mL, when compared with the washing with water. Overall, the T. zygis EO has demonstrated a promising antimicrobial activity and these findings point to the potential of the EO as a natural food preservative or sanitizer for controlling L. monocytogenes in food products. Highlights: T. zygis EO had antimicrobial activity against Listeria monocytogenes with a MIC of 0.05% (v/v). The EO influenced L. monocytogenes virulence by reducing biofilm formation and motility. Thymus zygis EO does not induce cross-resistance to antibiotics, belonging to different classes. The reduction of L. monocytogenes growth in chicken juice and in lettuce model media showed the preservative effect of EO. EO at 0.2% (v/v) for 5 min has potential to be used as natural sanitizer in vegetables.