Aseptic Techniques (MB Lab)

• Preventing contamination of cultures is important when working with microorganisms.
• Preventing contamination can be done by properly observing aseptic techniques
• are specific methods in handling sterile materials to exclude contaminating microorganisms from an environment

  aseptic techniques
• Ensure the purity of the microbial culture and prevents the laboratory personnel from being contaminated

  Aseptic techniques
• Preparation of Workstation

  1. Sanitize workstation or lab bench by wiping surface with paper towels to remove dust and dirt

  2. Disinfect surface by spraying generous amount of disinfectant solution all over the area

  3. Evenly distribute disinfectant on surface by wiping with paper towel in side-to-side and up-down pattern

  4. Allow disinfectant to dry before placing materials on surface

  5. Only necessary laboratory materials should be placed on workstations

  6. Repeat disinfection procedure after work is finished

  7. Discard paper towel inside designated waste bin
• Sterilization of Inoculating Wireloop or Inoculating wire

  1. Hold the wire loop at an angle and heat the loop and lower part of the handle over the flame until it becomes red hot. Pass the handle over the flame several times.
  2. Allow the loop to cool for several seconds by holding it but ensuring that it does not come in contact with anything.
• Transfer of microorganisms

  Tube to tube

  Tube to Plate

  Plate to Plate
• Transfer of Microorganism

  1. Hold the tubes with your left or right hand with the tube opening facing the flame of the alcohol lamp

  2. Open the tube by grasping the cotton plug or screw cap of the culture tube with the little finger of the left or right hand

  3. Briefly flame the mouth of the tubes

  4. Insert the sterile wireloop into the culture tube and obtain a small amount of inoculum

  5. Inoculate the second culture tube in zigzag manner on the surface of the solid medium if it is a slant. If the culture medium is broth, dip the loop in the broth and dislodge the cells by gently shaking the loop in the broth

  6. Flame the mouth of the tubes again before replugging. Do no interchange the plugs

  7. Sterilize the loop
• Pouring of culture media or inoculum from flask or tube to plate

  1. Remove the cotton plug of the container with the culture media or microbial suspension using the finger of the right or left hand
  2. Flame the mouth of the container. Without putting down the plug, transfer the container to the other hand
  3. Get the Petri dish with your free hand and slightly open the lid
  4. Pour the culture medium or inoculum
  5. Immediately cover the plate and place it on the table
  6. Flame the mouth of the container and replace the plug