Antibiotic Experiment Flashcards
(10 cards)
Explain the aseptic techniques that should be used?
- Wash your hands with soap and disinfect surfaces in order to prevent contamination.
- Sterilise the pipette in order to prevent contamination.
- Flame the neck of the bootle of bacteria to prevent contamination.
- Work near an are that has an upward current of air in order to draw air-borne microbes away and prevent contamination.
- Lift the petri dish slightly and at an angle to prevent contamination.
Describe a method to investigate the effect of antimicrobial substances on microbial growth.
- Use a sterilised pipettes to transfer bacteria from the broth to the agar plate using aseptic techniques.
- Use a sterilised spreader to venky spread the bacteria acroos the plate.
- Use sterilised forceps to place discs that have been soaked in different antimicrobial substances for the same amount of time onto the agar plate.
- Lightly tape the lid onto the agar plate, Inver and incubate at 25 degrees.
- Measure the diameter of the inhibition zone around each disc and use that to calculate the area.
Explain why it is important to maintain a pure culture of bacteria?
Foreign bacteria may outcompete the bacteria being investigated.
Explain why the lid is held with two pieces of tape and not sealed completely.
- Allows oxygen to enter the agar plate and prevents the growth of anaerobic bacteria.
2 This type of bacteria might be more pathogenic.
Explain why a paper disc with water is used.
- To act as a control.
- To ensure that the presence of the antimicrobial substances is what’s causing the change in growth and not anything else.
Explain why the petri dishes are incubated upside down.
So that the codensation drips onto the lid and not the bacteria culture.
Explain why a very high contraction of antimicrobial substances shouldn’t be used?
They may kill a lot of bacteria causing the inhibition zones to overlap.
Explain why bacteria should be incubated at 25 degrees.
It is below the body temperature and prevents the growth of pathogens.
Explain the presence of the inhibition zones?
- Clear zone: The antimicrobial diffuses out of the dics ans into the agar. This kills the bacteria.
- The larger the clear zone the more effective the microbial is at killing bacteria.
- No clear zones means the bacteria may be resistant to the antimicrobial or the antimicrobial is not effective at killing bacteria.
How can the data be presented?
- Bar charts: Have the name of each antimicrobial on the y- axis and the area of the inhibition zones on the X-axis.
- Line graph: Have the concentration of the antimicrobial substance on the Y-axis and the are of inhibition zones on the X-axis.
