Evaluation of the antibacterial activity of some medicinal plants on Listeria monocytogenes
Evaluation of the antibacterial activity of some medicinal plants on Listeria monocytogenes
Yousef Alaee Mollabashi,1,*Peyman sefidi,2Nima Foroutan,3
1. Department of Biology, Tabriz Branch, Islamic Azad University, Tabriz, Iran 2. Department of Biology, Tabriz Branch, Islamic Azad University, Tabriz, Iran 3. Department of Biology, Ardanil Branch, Islamic Azad University, Ardabil, Iran
Introduction: One of the gram-positive bacteria that is highly important in terms of pathogenicity in food sources used by humans and in recent years studies have been conducted to investigate the prevalence of this bacterium and controls to reduce its activity is the rod-shaped bacterium Listeria monocytogenes. This catalase-positive, spore-free bacterium can have profound and severe effects on infants and the elderly, such as death, which is more common than in people of other ages. Listeria monocytogenes bacteria, when it enters a person's body, we see various complications and diseases such as meningitis, abortion in pregnant women, etc. In most cases, human listeriosis is caused by Listeria monocytogenes serotype 4. Among the factors that have been proven in various studies and can increase the risk of pathogenicity of this bacterium, the presence of this bacterium in different environments and foods and even low storage temperature is not a barrier against the activity of this oxidase-negative bacterium and sodium chloride also, up to 10 to 12.5% is not effective on the activity and proliferation of this bacterium. Other risk factors include the very small amount of this bacterium that can cause infection in the host. On the other hand, in 2008 it was stated that about 70% of infectious diseases are transmitted through food. In the case of Listeria monocytogenes, it can be said that various foods from vegetables to dairy, from seafood to other food sources can be contaminated and transmitted, but raw milk and soft cheese are the most contaminated in dairy products with Listeria monocytogenes. Now, chemical or natural preservatives can be used against the activity of this pathogenic bacterium, but because some people in the community think that preservatives are of chemical origin, pay attention to natural and plant preservatives such as plant extracts and essential oils that can eliminate pathogens are attracted. Essential oils are obtained in liquid and fragrant form from the plant. The vulnerability of the cell wall of microbial pathogens against essential oils derived from medicinal plants is one of the causes of microbial death. In the essential oils of medicinal plants, there are many compounds such as alpha-pinene, gamma-terpinene, phenol, etc that play an important role. In addition to bacteria, plant essential oils can also be used to kill molds and yeasts. During the many years that essential oils have been used as a preservative, not only promising results have been observed, but also the effect on the taste, smell, colour, etc. of the food has prevented the essential oils from being widely used. The purpose of this review article is to review the results of a series of studies on the anti-listerial properties of some medicinal plants.
Methods: Using keywords related to the purpose of this study, such as the antibacterial properties of medicinal plants, anti-listerial activity of medicinal plants, etc., we applied to find the desired references without applying a specific time interval.
Results: In a study conducted by Dr Jalali et al., the hydroalcoholic extract of eucalyptus showed more and better anti-listerial effects in both tubular dilution and disc diffusion methods than the other plants studied in that study. The result of a study in 2008, in which mint oil extract was inoculated at three different concentrations on 1000000 Listeria monocytogenes bacteria was used per gram of cheese at two different temperatures of 7 and 15 ° C at regular intervals. And they reported that mint extract was effective against this gram-positive bacterium. In previous years, black seed was used on the growth and activity of this bacterium, and in addition, the antibiotic gentamicin was used, which was reported to be much more effective than the antibiotic used. In one study, researchers used 3 concentrations of thyme extract on Listeria monocytogenes, and at the end of that study, the antimicrobial effect of this plant extract was confirmed. Comparing the results of different studies for various reasons such as essential oil production, plant growth stages, low concentration of essential oil in the extract, type of solvent, extraction method, etc. is more difficult to easily comment on the effectiveness of different plants.
Conclusion: Nowadays, due to various problems in controlling and suppressing pathogens by a group of common drugs and the need of the international community to develop new and effective therapies such as medicinal plants with antimicrobial properties, nanoparticles, etc is needed.