The method for spreading bacteria on an agar plate involves using a sterile spreader to evenly distribute the bacterial sample across the agar's surface.
Step-by-Step Guide to Spreading Bacteria:
- Preparation: Begin with a prepared agar plate and a bacterial sample.
- Holding the Spreader: With your right hand, gently hold the sterile spreader.
- Applying the Sample: Place a small amount of your bacterial sample onto the surface of the agar plate.
- Spreading the Sample:
- Gently hold the spreader on the surface of the agar.
- As the turntable is spinning, move the spreader back and forth across the plate to distribute the sample.
- Ensure you spread the sample evenly over the entire plate.
- Absorption: Allow the sample to absorb completely into the agar. This should take at least 5 minutes before inverting the plate for incubation. As stated in the provided reference, "Allow the sample to absorb thoroughly (at least 5 minutes) before inverting the plate for incubation."
Key Considerations:
- Sterility: Maintain a sterile environment throughout the process to avoid contamination. Use a new, sterile spreader for each plate.
- Even Distribution: The goal is to achieve an even distribution of bacteria, ensuring individual colonies can grow.
- Gentle Touch: Avoid pressing the spreader too hard on the agar surface, as this can damage the agar.
- Absorption Time: The waiting time before incubation allows the sample to be absorbed fully into the agar, preventing issues during incubation.
