Antimicrobial Activity of Commonly Used Herbs and Spices
Tahreen Mohamed, Nabila Harjee
Collingwood School
Floor Location : S 163 H

For our project, we decided to test the antimicrobial activity of some commonly used herbs and spices. Ayurveda is a complete health care system used in India to this day, with doctors who practice only Ayurvedic treatment and believe that almost all sicknesses can be cured with these plants. We wanted to test whether there was any Ayurvedic activity in commonly used herbs and spices against a bacterium and some fungi. We tested the effect of seven herbs and spices (turmeric, salt, garlic, ginger, cloves, chilli pepper, and cumin) and one control (food grade blue dye) on four types of fungi and one type of bacterium. After some research, we hypothesized that the turmeric and the salt would each have the most effective medicinal and preservative properties, respectively. We took 80 potato dextrose agar dishes and placed two plugs of fungi at the outer edges of the plate or two streaks of bacteria across the plate. Along with the organisms, we made a hole in the centre of the agar and filled it with approximately 5 mL of the extract. We assumed that the agar would allow the extract to diffuse from the centre of the plate to the edges and affect the growth of the organism in each plate. In our control plate, once the organism had grown to the centre of the dish, we were able to obtain our results. Our findings supported our hypothesis that turmeric and salt were among the most affective antimicrobial compounds of the extracts tested. Garlic, which is also known to have medicinal properties, also had a significant effect on the growth of the organisms, while chilli pepper or cumin had far less of an effect on the organisms than the other test materials. With reference to our Graphs outlining the Standard Deviation of the substances we can tell that some extracts were more consistent than others while others had wider ranges of growth rates depending on the organism it was acting on. Also these charts reveal the mean growth, of the organisms affected by the extract, taken from multiple measurements of the growth rate. Overall, our experiment allowed us to establish and prove which herb or spice had the strongest Ayurvedic properties based on the organism managed to grow, which is what we had set out to do. These results have applications to food preservation, improving health, and as antimicrobial uses.