Antimicrobial properties in plants Flashcards
State six aseptic techniques.
-Wipe down surfaces with antibacterial cleaner before and after the experiment.
-Use a Bunsen burner in the workspace so convection currents draw microbes away from the culture.
-Flame the wire hoop before using it to transfer bacteria.
-Flame the neck of any bottles before using them.
-Keep all vessels containing bacteria open for the minimum amount of time.
-Close windows and doors to limit air currents.
How is a plant extract prepared?
Grind the selected plant sample into a paste and add a few cm3 of ethanol.
How is the control of the practical set up?
Dip a filter paper disc in ethanol and place it on the agar plate.
Why are bacteria incubated at 25°C?
To prevent the growth of pathogens (harmful bacteria) which occurs at higher temperatures.
How can you compare the effectiveness of different extracts applied to the same bacteria?
Measure the diameter and calculate the area of the zone of inhibition (clear zone) on the agar.
What does the zone of inhibition indicate?
It indicates the bacteria killed by the antibiotic. The larger the zone, the more effective the antimicrobial properties of the plant.
State the hazards and precautions of this practical.
Naked flame: keep away from flammable materials, tie hair up and wear goggles.
Bacteria is a biohazard, use disinfectant and wash hands.
Disinfectant is flammable, keep away from naked flame.
Why should the lid not be completely taped to the petri dish?
To allow oxygen to enter the petri dish, preventing the growth of harmful anaerobic bacteria.
Why is the petri dish incubated upside down?
To prevent condensation from forming on the lid and dripping down onto the agar.
Describe the graph that can be plotted from the results of this practical.
A bar chart of the zone of inhibition against plant extract.
