RP6-aseptic technique Flashcards
why use equipment that had been in an autoclave
to sterilise the equipment
describe the steps used to transfer bacteria from bottle to petri dish
- wash hands and disinfect surface
- flame sterilise inoculating loop
- flame sterilise neck of bottle holding culture of bacteria
4.streaking plate with inoculating loop quickly - only lifting the lid of the
petri dish a small amount
explain why surfaces are disinfected and hands are washed after the experiment
to kill harmful/pathogenic bacteria so they don’t harm anyone
5 aseptic techniques
- Wipe down surfaces with disinfectant before & after experiment
- Set up convection current using Bunsen burner to rid of microorganisms from the cultures and reduce contamination
- Flame the inoculating loop
- Flame the neck of bottles before using
- Keep vessels containing bacteria open for minimum length of time
what is the solid growth medium
agar jelly
what is a bacterial lawn
when the whole dish is covered by bacteria
What temperature do you incubate at and why
Room temperature: 25
This encourages growth of bacteria without growing human pathogens which thrive at body temperature (37°C).
Why don’t you fully seal the petri dish
Allows O2 in to prevent selection for anaerobic bacteria
allows O2 for aerobic respiration
Why do you invert agar plates when placing them in the incubator?
Prevents layer of condensation forming so allows o2 to enter, to prevent harmful anaerobic bacteria growing.
Describe the graph that can be plotted
Bar chart of inhibition zone area against antibiotic
what is a colony of bacteria
Group of bacteria that are genetically identical
How to make a streak plate
Use sterilised inoculating loop / dip in culture and smear over plate
how to perform a serial dilution
Starting with an original stock solution and subsequently diluting it by the same factor each time
Method to create and measure inhibtion zone round each disc
- Carry out aseptic technique
- Use sterile inoculating loop to transfer bacteria from broth to agar plate
- Spread bacteria evenly using sterile plastic spreader
- Use sterile forceps to place disc dipped in antibiotic on the plate
- Lightly tape the lid on, invert and incubate at 25 degrees c for 48 hrs. Don’t tape around entire dish
- Sterilise equipment and disinfect work surfaces
- Measure diameter or inhibition (clear) zone without taking off lid
- Calculate area of inhibition zone using pi R squared
What temp you incubate at and for how long
25,48
