Which of the following is the correct way to open an agar plate to remove a sample or to inoculate it?

• A. Completely remove the lid and place it on the bench while working.
• B. Invert the plate and work on the agar with the lid on the bottom.
• C. Lift the lid just enough to access the agar, keeping it close to the plate and minimizing exposure to the air.
• D. Hold the lid open at a 90-degree angle for maximum visibility.

Answer: (C)

Verified step by step guidance

1. Understand the purpose of opening an agar plate: to minimize contamination while accessing the agar surface for sampling or inoculation.
2. Recognize that completely removing the lid and placing it on the bench exposes the agar to airborne contaminants, increasing the risk of contamination.
3. Note that inverting the plate and working with the lid on the bottom is impractical and can lead to contamination or spillage.
4. Consider that holding the lid open at a 90-degree angle exposes a large surface area of the agar to the air, increasing contamination risk.
5. The best practice is to lift the lid just enough to access the agar, keeping it close to the plate to create a barrier against airborne contaminants, thus minimizing exposure.