6 - ASEPTIC TECHNIQUES

• AIM?

  use of aseptic techniques to investigate the effect of antimicrobial substances on microorganism growth
• PURPOSE OF ASEPTIC TECHNIQUES?

  avoid contamination of sample from outside microorganisms and prevent contamination of environment with bacterial culture
• ASEPTIC TECHNIQUES?

  1. Sterilise surfaces with antibacterial cleaner before and after
  2. Use Bunsen burner to create convection currents to draw microorganisms away
  3. Flame inoculating loop to sterilise before transferring bacteria
  4. Flame neck of bottles to prevent microorganisms from air entering bottle
  5. Keep all vessels containing bacteria open for minimum amount of time
• WHAT TEMPERATURE SHOULD THE BACTERIA BE INCUBATED IN?

  • 25 degrees Celsius in school to prevent rapid growth of bacteria
  • 37 degrees Celsius in lab to replicate conditions in human body
• WHEN TAPING PETRI DISH WHAT SHOULD YOU DO?

  not tape round entire dish to allow oxygen to enter, to prevent growth of harmful anaerobic bacteria
• INDEPENDENT VARIABLE?

  type of antibiotic/ type of disinfectant/ concentration of disinfectant
• DEPENDENT VARIABLE?

  area of zone of inhibition
• CONTROL VARIABLES?

  • temperature (25 degrees Celsius)
  • type of bacteria
  • volume of bacteria
  • type of agar
  • volume of agar
  • spread of bacteria
  • time
• CONTROL EXPERIMENT?

  paper dish soaked in distilled water to ensure paper has no effect and act as a comparison
• RISK ASSESSMENT?

  biohazard contamination risk, reduced using aseptic techniques