Required Practical 6 - Aseptic Techniques Flashcards
What are the 6 aseptic techniques
- wipe down surfaces with antibac cleaner
- use bunsen burner to create convection currents
- flame the wire hoop before use
- flame the neck of the bottle
- keep vessel containing bacteria open for short amounts of time
- close windows and doors to limit air currents
Why is bacteria incubated at 25C
Tp prevent growth of pathogens which occurs at a higher temperature
How can you compare the effectiveness of different antibiotics applied to the same bacteria
Measure the diameter and calculate the area of the zone of inhibition
What does the zone of inhibition indicate
Indicates the bacteria killed by the antibiotic
Hazards in this practical
- naked flame (tie up hair)
- bacteria is a biohazard (disinfect)
- disinfectant is flammable (keep away from naked flame)
Why should the lid not be completely taped
To allow oxygen to enter the petri dish to prevent the growth of harmful anaerobic bacteria
How would you graph the results
A bar chart of the zone of inhibition against antibiotic
method
- evenly distribute bacteria on an agar plate (lawn spreading)
- use a range of at least 5 different compounds/ concentrations
- keep other variables the same
- use aseptic technique
- use a single species of bacteria
- incubate at 25C for 24 hrs
- measure the clear zone of inhibition
- use a control disk to show the differences are due to treatment
- repeat at least 5 times
clear zone
- if it is not round take the mean diameter
- antimicrobial compound diffuses out of the disc and inhibits the growth of the bacteria
- find minimum concentration with equal size clear zone to largest
importance of aseptic techniques
- avoids the presence of unwanted microorganisms
- no competition for nutrients
- conditions remain unchanged
- ne decrease in yield
- prevent the escape of microorganism
aseptic teachnique definition
lab procedures that are performed under sterile conditions to prevent contamination
