Required Practical 6 - Aseptic Technique Flashcards
Suggest why aseptic technique is necessary
- prevent contamination of cultures from environment which could nullify investigation
- environment not contaminated by potentially hazardous microorganisms
Suggest a potential risk of working with non-pathogenic bacteria
Could mutate into a disease-causing strain
Suggest why agar plate is labelled on underside
- lid could get lost
- culture is inverted during incubation so easier to identify is underside is labelled
Suggest why the neck of bottle containing culture is flamed
- produces a convection current away from opening
- prevent entry of microorganisms
Suggest why lid of agar plate is lifted at an angle facing Bunsen burner
- creates a convection current upwards from plate
- prevents microorganisms from air contaminating plate
Suggest why an inoculating loop is preferred to a plastic spreader
- plastic spreader cannot be flamed like an inoculating loop since there is risk of breakage
- must be dipped in ethanol and passed quickly though flame
Give ways in which aseptic conditions are maintained
- bench sprayed with disinfectant
- sterile pipette and spreader used
- Bunsen burner to flame inoculating loop and neck of bottle containing culture
- lid of agar plate lifted slightly and towards Bunsen burner
Suggest why two pieces of adhesive tape are used to seal agar plate as oppose to sealing around it
- allows free passage of air
- normal growth (rather than promoting growth of anaerobic bacteria)
Suggest why cultures are not incubated above 30 degrees Celsius
Reduces risk of growing microbes that are pathogens to humans
Suggest why inhibition zones are measured with the plate upside down
Clearer observations due to condensation on lid
Suggest why agar plates are incubated upside down
Prevents droplets of moisture which form during incubation falling on culture
