Antimicrobial Effects of Cilantro free essay sample

A drop of cilantro juice and water in varying concentrations (1:10, 1:20, 1:40, 1:80) was added to a nutrient agar plate inoculated with S. epidermis and a nutrient agar plate inoculated with E. coli. The plates were incubated for 48 hours and then observed for a zone of clearing where the cilantro juice drop was placed. Cilantro was found to not display antimicrobial activity against either bacterium in the experiment in any of the different dilutions. These results could have to do with the possible contamination of cilantro or the specific bacteria we chose to target. Additional studies of cilantro should be conducted on different types of bacteria in order to gain a better understanding of how the herb works as an antimicrobial. Introduction Herbs and spices have been used for many years for their health benefits and antimicrobial properties (Lai amp; Roy, 2004). Cilantro, an herb found in many ethnic food dishes, has been shown to have an antibacterial effect on Salmonella choleraesuis due to the compound dodecanal found in the leaves. Dodecanal was found to be twice as potent as the antibiotic gentamicin that is commonly prescribed for Salmonella infections (Kubo, Fujita, Kubo, Nihei, amp; Ogura, 2004). The antimicrobial properties of cilantro have also been demonstrated against the bacteria’s Staphylococcus aureus, Bacillus cereus, Escherichia coli (Marsh amp; Arriola, 2009). We decided to conduct our own experiment to see if cilantro had any antimicrobial effect on the bacteria’s Staphylococcus epidermis and Escherichia coli. Experiments about the antimicrobial properties of herbs re interesting because their results can affect the way people choose to eat. For example, if a certain herb is found to delay food spoilage then perhaps people will choose to include it more often in their cuisines. Or, if a study finds that an herb has an antibacterial effect on an organism commonly found on produce, perhaps a fruit and vegetable wash could be produced that contains the herb in order to help prevent inf ection. We chose both a gram positive bacterium (S. epidermis) and a gram negative bacterium (E. oli) to see if a bacterial outer membrane would inhibit any antibacterial effect of cilantro. Gram negative bacteria have an outer membrane and gram positive bacteria do not (Tortura, Funke, amp; Case, 2010). We predicted that cilantro would have an antimicrobial effect on S. epidermis but not on E. coli. We inoculated two nutrient agar plates, covering each with one of the bacteria’s, and divided each plate into quarters. We then placed one drop of cilantro juice mixed with water in each of the four sections in different concentrations. This allowed us to see if a minimum concentration of cilantro was needed to produce an antimicrobial effect. We then incubated the plates at 37 degrees Celsius to allow the bacteria to grow and evaluated the plates after 48 hours. We expected to see a clearing of bacteria in at least one of the quadrants of the plate containing S. epidermis and did not expect to see any clearing of bacteria on the E. coli plate. Methods 1. Label one nutrient agar plate S. epidermis and one nutrient agar plate E. coli and divide each plate into quarters. Label each quarter with the different dilutions : 1:10, 1:20, 1:40, and 1:80. 2. Inoculate and label one water blank with S. epidermis and one water blank with E. coli. 3. Create a lawn plate of S. epidermis by dipping the inoculating loop into the water/S. epidermis tube and streaking the loop across the nutrient agar plate labeled S. epidermis. The entire surface of the plate should be inoculated with bacteria by zigzagging the loop across the plate after every quarter turn. After the initial zigzag, the plate should be turned three more times for streaking to be performed. Repeat this process by making a lawn plate of E. coli. 4. Put nine drops of sterile water into one of the depressions of the sterile spot plate using a sterile Pasteur pipette and a third unused sterile water blank. Put five drops of sterile water into three more depressions of the sterile spot plate. 5. Ground cilantro using a mixer or juicer and add the last sterile water blank to the cilantro in order to obtain a drop of cilantro juice. 6. Put the cilantro juice drop into the first depression of the sterile spot plate that already has the nine drops of water in it using a sterile eye dropper. This creates a dilution of cilantro of 1:10 (1 drop cilantro juice out of a total of 10 parts/drops). 7. With the same sterile Pasteur pipet used to add water to the sterile spot plate, mix the cilantro juice and water contained in the first depression of the sterile spot plate. Put one drop of the first depression mixture into the section of the S. epidermis nutrient agar plate labeled 1:10. Repeat this step for the E. coli nutrient agar plate. 8. Using the same first Pasteur pipet, put five drops of the first depression mixture into the second depression of the sterile spot plate. Take a new, second sterile pipet and mix the cilantro juice and water contained in the second depression of the sterile spot plate. Put one drop of the second depression mixture into the section of the S. epidermis nutrient agar plate labeled 1:20. Repeat this step for the E. coli nutrient agar plate. 9. Using the same second Pasteur pipet, put five drops of the second depression mixture into the third depression of the sterile spot plate. Take a new, third sterile pipet and mix the cilantro juice and water contained in the third depression of the sterile spot plate. Put one drop of the third depression mixture into the section of the S. epidermis nutrient agar plate labeled 1:40. Repeat this step for the E. coli nutrient agar plate. 10. Using the same third Pasteur pipet, put five drops of the third depression mixture into the fourth depression of the sterile spot plate. Take a new, fourth sterile pipet and mix the cilantro juice and water contained in the fourth depression of the sterile spot plate. Put one drop of the fourth depression mixture into the section of the S. epidermis nutrient agar plate labeled 1:80. Repeat this step for the E. coli nutrient agar plate. 11. Incubate both nutrient agar plates at thirty seven degrees Celsius for at least forty eight hours. Results Cilantro did not display antimicrobial activity against S. epidermis and E. coli in our experiment. A clear zone where the cilantro juice drop was placed would be indicative of cilantro acting as an antibiotic because bacteria would be cleared from the area. Both the S. epidermis and E. coli lawn plates showed no clearing in any of the four dilution sections (1:10, 1:20, 1:40, 1:80) where a drop of cilantro juice was placed. Interestingly, there was additional microbial growth where the cilantro juice drop was placed.