This is a deliberate process that must be mastered to work in a microbiology lab. In a wet lab, this is done by picking up the tube of inoculum with the non-dominant hand so the dominant hand can use a sterile cotton-tipped applicator (swab) to collect and transfer bacteria for creating the lawn. The cap is removed from the tube by the pinkie of the dominant hand, the mouth of the tube is flamed, and the inoculum is acquired. Then the tube is flamed again and the cap replaced before it is set back in the rack. At this point, the lid of the plate is removed and the swab is used to streak the inoculum onto the sterile agar plate, covering the entire surface with cells to hopefully result in a lawn of confluent bacterial growth. Once done, the lid is replaced and the swab is placed in biohazard waste for autoclaving. Skilled microbiologists have a routine for doing this and can make a lawn in less than a minute.
Here’s what it looks like in the VUMIE Online© Online Lab.
- Turn on the incinerator.
- Select the sterile cotton-tipped applicator (swab) from the Lab Tools options. Don’t flame your swab!
- Select the medium to be inoculated. It will appear along with a pure culture of inoculum on the lab bench – tube of inoculum at left and sterile agar plate at right.Place the cursor over the cap of the inoculum tube and click to bring up the action menu. Select “Toggle Caps/Lids”. The tube cap and plate lid will be removed.
- Flame the mouth of the tube. Look for the message indicating this has been done.
- Move the tip of the swab down into the inoculum broth. A message will appear indicating success. You must enter and leave the tube through its mouth. You now have a swab holding lots of bacteria for the transfer.
- NOTE: Our Virtual Lab deviates somewhat in the following steps from the description above of actual tube-plate transfers in a wet lab. Now move the tip of the swab with collected bacteria over to the sterile agar plate and squiggle the swab over its surface. The appearance of the plate will change as the inoculum is spread, and a message will appear indicating success.
- Flame the mouth of the inoculum tube. Look for the message indicating this has been done.
- Place the cursor over the mouth of the inoculum tube and click to bring up the option to “Toggle Caps/Lids” (or double click). Do this to replace the tube cap and plate lid.
- Look at the Traffic Signals to insure you have two green lights, indicating a successful tube-to-plate aseptic transfer.
- Do not worry about flaming your swab or disposing of it in Biohazard waste – this is done automatically as you continue with your work.