Testing Plants as Potential Medicines
Purpose:
The objective of this lab is to find whether or not some of the plants in a given area contain substances with medical properties.
Procedure:
Part 2:
Part 3:
TLAB Questions:
Q: If an extract gives a negative result in the antimicrobial assay, does that mean that the extract is not an antimicrobial agent?
A: Not necessarily. The extract could be repellant to a specific type of bacteria, which was not present in the E.Coli culture we used as a test subject. Q: In preparing the sample disks, some of the methanol extractions smell like alcohol. Why is that a problem? A: The problem is that alcohol is known for being a strong bacteria killer. if you were testing a plant, but you had alcohol as one of the components in the mixture, you could not be sure whether the plant or the alcohol did the bacteria-killing. The experiment would not be pure. Q: Each extract may have one or more compounds in it. What should be done to begin to identify the exact compound in an extract that is causing the antimicrobial action? A: Each compound may have one or more compounds in it. In order to identify the exact compound in an extract that is causing microbial action, scientists can use chromatography. By utilizing this method, scientists can filter and separate compounds through "thin chromatography," where individual molecules are separated based on polarity. |
Materials:
- balance, weight boat, lab scoops
- LB broth base - media bottles, 250 mL - sterilizer/autoclave - water bath, 37 degrees Celsius - sterile LB agar - laminar flow hood and disinfectant - plastic safety glasses - Bunsen burner and gas lighter - inoculating loop, Ni/Cr wire - petri dishes, 60 x 15 mm, sterile - E. coli JM109 (stock plate) - plant specimen - mortar and pestle - pipet, 10 mL and pump - short-stemmed plastic funnels - filter paper disks, 5 mm diameter - Beakers, 100 mL - syringe, 10 mL and filter, 0.2 microliters - reaction tubes and rack, 1.7 mL - absolute methanol - pipet, 1 mL and pump - dry block heater/heat block - fine-tipped forceps - ampicillin - glass spreader - incubator oven, 37 degrees Celsius - forceps - alcohol Analysis and Conclusion:
For the plant I had chosen as my test subject, stinging nettle, three of the results were weakly positive, while one was negative. Both of the water disks tested as weakly positive, while only one of the methanol disks turned out as positive. Since the controls turned out as expected, there is a good probability of these results being accurate.
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