Bacteria in Plants
Purpose:
What plant materials, found locally, contain active ingredients that will inhibit growth of bacteria?
Materials:
What plant materials, found locally, contain active ingredients that will inhibit growth of bacteria?
Materials:
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Procedure:
Part 2: Preparing Plant Extracts
Part 3: Setting Up Antimicrobial Plant Extract Assay
Results:
Part 2: Preparing Plant Extracts
- Grind up 2 g of plant tissue with deionized water. Let it sit for 3 minutes
- Filter sample through an 11 cm paper funnel
- Filter sterilize the sample using an syringe filter
- Collect 1 mL of sample into a 1.7 mL microtube
- Repeat above steps, but replace water with methanol
- After the extraction, place the microtube with methanol extract in a 65 degree celsius heat block with the caps off for at least 1 day to evaporate the methanol
- For other 4 samples, repeat the above steps
- Drop 3 filter paper discs into each tube with sterile forceps
- Prepare 3 negative control discs of only methanal and only sterile distilled water
- Close tubes and wait enough time for enough extract to be saturated
Part 3: Setting Up Antimicrobial Plant Extract Assay
- Using sterile pipets transfer 1 mL of E. coli broth to the middle of the petri dish (divided into 4 quadrants)
- Evenly spread the culture around the plate using a sterilized spreading loop
- Cover and allow culture to soak into the agar for at least 15 minutes
- Using sterile forceps place discs into corresponding quadrants
- Incubate at 37 degrees celsius for 1 day
Results:
- Both my positive and negative controls turned out as expected.. There was a 1.5 mm diameter circle of bacteria-free area around the ampicillin discs and a 1 mm diameter bacteria-filled circle around the water disc.
Analysis/Conclusion
My water extract of my O'Hair site plant gave me positive results. Everything worked as expected but some errors could be contamination, mismeasurement, and mix up of plants.
Thinking Like a Biotechnician Questions
My water extract of my O'Hair site plant gave me positive results. Everything worked as expected but some errors could be contamination, mismeasurement, and mix up of plants.
Thinking Like a Biotechnician Questions
- If an extract gives a negative result in the antimicrobial assay, does that mean the extract is not an antimicrobial agent? Not necessarily, because the extract could still be an antimicrobial agent, but not for that particular bacteria.
- In preparing the sample discs, some of the methanol extractions smell like alcohol. Why is it a problem? It is a problem because alcohol kills bacteria and that would defeat the purpose of the lab.
- 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? We could use chemical reactions to separate individual components and then test each one to see what causes the reaction.