Screening of antimicrobial, anti-quorum sensing activity and cytotoxicity of origanumoil against Gram-positive and Gram-negative bacteria

Introduction and Aim: Essential oils have been used from ancient times to treat different gram-positive and gram-negative bacterial-related infections. The study aims to screen the antibacterial, anti-quorum sensing activity of origanum oil against the common infection causing gram-negative and gram-positive bacteria. Material andMethods: The MIC (minimum inhibitory concentration) and antibacterial activity of origanum oil against the eight bacterial species, namely, Pseudomonas aeruginosa, Shigella flexneri, Salmonella enterica, Klebsiella pneumoniae, Streptococcus pneumonia, Streptococcus pyogenes, Staphylococcus aureus, and Enterococcus faecalis, was assessed by broth-dilution method and well diffusion method. The anti-quorum sensing activity was analyzed using bioreporter strain CV026 at sub-MIC concentrations, while the cytotoxicity of the origanum oil was analyzed using the SW480 cell line. Results: The oil's antibacterial activity was analyzed by measuring the clear inhibitory zone diameter, and maximum inhibitory zone of 36.66 mm zone against Staphylococcus aureus (Gram-positive) and 33.33 mm against Salmonella enterica (Gram-negative) of origanum oil was measured. And the minimum inhibitory zone of 16.66 mm zone of Enterococcus faecalis (Gram-positive) and 19.66 mm against Klebsiella pneumoniae (Gram-negative) of oil was noted. And the lowest MIC (0.1 mg/ml) of oilwas found against Streptococcus pneumonia. The oil significantly inhibited the violacein pigment production (30.29 %) at 0.02 mg/ml concentration (this oil concentration did not significantly affect the growth curve). The in vitro cytotoxicity assay shows that the oil inhibited the SW480 cells growth with increasing concentration. Conclusion: The origanum oil possesses antibacterial and anti-quorum sensing activity and can be used as an alternative for treating tested bacterial infection.

The Influence of Two-Component Mixtures from Spanish Origanum Oil with Spanish Marjoram Oil or Coriander Oil on Antilisterial Activity and Sensory Quality of a Fresh Cut Vegetable Mixture

The aim of this study was to evaluate two-component mixtures of essential oils (EOs) in sub-inhibitory concentrations for antilisterial protection of minimally processed vegetables. Spanish origanum oil (SOO), Spanish marjoram oil (SMO) and coriander oil (CO) and a mixture of fresh leafy vegetables with red beet were used. The chemical compositions of selected EOs were analyzed by gas chromatography. Carvacrol was the major component of SOO. The dominant active component of SMO was 1,8-cineole, while the major constituent in CO was linalool. The study shows that essential oils in combination, namely SOO + SMO and SOO + CO in a ¼ MIC + ¼ MIC (Minimal Inhibitory Concentration), have a synergistic effect against L. monocytogenes. The reduction of L. monocytogenes in vegetable mixtures treated by EOs in these selected combinations after 24 h of storage was approximately equal to the limit of detection. Furthermore, it was found that the vegetable mixture treated with SOO + SMO had the highest-rated sensorial quality and could therefore meet consumer expectations.

Microbial Decontamination of Fresh Produce (Strawberry) Using Washing Solutions

<p>This study was carried out to determine the effect of natural antimicrobial washing solutions against microbial growths on fresh produce specifically strawberries. Selected washing solutions used for strawberry washing, and treatments were sterile water (control), white vinegar (VI), crude lemon juice extract (LE), VI+Origanum oil (VIO), LE+Origanum oil (LEO), and VI+LE+Origanum oil (VILEO). From the preliminary study of antimicrobial activity of washing solutions in aqueous model system tested at 2, 5, 10, 15, 20 and 25 min against <em>S.</em> Typhimurium, washing time was determined as 5 min to be used for this study. After the washing, strawberries were stored at 4 °C for 5 days. Results showed that all natural washing solutions exhibited inhibitory effect against total aerobic bacteria, yeast and mold. On day 5, compared to the control, all washing solutions significantly reduced <em>S.</em> Typhimurium by 2.7 Log CFU/g (P&lt;0.05). Color results showed that samples color were slightly changed by washing with VIO and VILEO. However, there was no significant difference in total color change on strawberries compared to the control (P&gt;0.05). Based on the results, it is indicated that the combination of vinegar with crude lemon juice extract and essential oil might be suitable as natural sanitizer for decontamination of fresh produce.</p>