Aseptic Technique

Aseptic Technique in Bacterial Transfer

• Aseptic technique aims to transfer a bacterial culture into fresh media without introducing contaminants.

• All fresh media should be appropriately labeled with the names of the bacterial cultures being used.

Tools for Transferring Bacteria

• Inoculating Loop: A thin wire loop used to transfer samples of bacteria.

• Inoculating Needle: A straight wire used mainly for stab inoculation into agar medium.

Sterilizing the Inoculating Tools

• Pass inoculating tools through the hottest part of the flame of a Bunsen burner, which is the blue cone.

• This sterilization process kills any contaminants on the tool.

• Important Note: After sterilization, do not touch or set down the inoculating tool on any surface.

• Always work close to the flame to maintain an aseptic environment, as the flame reduces airborne contaminants.

Transferring Bacteria from Culture to Agar Plate

1. Prepare for Transfer:- Hold the sterilized inoculating tool in your dominant hand.

   • Your other hand should hold the bacterial culture (test tube).

2. Handling the Culture:- Remove the cap of the test tube using your dominant hand while keeping the other hand steady.

   • Pass the mouth of the test tube through the flame several times to sterilize it.

3. Inoculating the Medium:- Dip the sterilized inoculating tool into the liquid culture, then remove it.

   • Sterilize the mouth of the test tube again before replacing the cap.

4. Inoculating the Agar Plate:- Lift the lid of the agar plate at a 45-degree angle using your free hand, holding it as a shield against contaminants.

   • Streak the inoculating tool over the entire surface of the agar plate in all directions.

   • Rotate the plate a quarter turn between streaking to ensure even placement of bacteria across the surface.

   • Confirm that bacteria are evenly distributed across the plate.

Completing the Process

• After inoculation, sterilize the inoculating tool again using the flame.

• Properly discard all contaminated tools and waste into a biohazard container to maintain safety.

• Disinfect the bench surface to ensure a clean working area for future experiments.