Which of the following techniques results in isolated colonies both within the agar and on top of the agar?

• A. Serial dilution without plating
• B. Pour plate technique
• C. Streak plate technique
• D. Spread plate technique

Answer: (B)

Verified step by step guidance

1. Understand the goal: The question asks which microbiological technique results in isolated colonies both within the agar and on top of the agar surface.
2. Recall the characteristics of each technique: Serial dilution without plating does not involve growing colonies on agar, so it cannot produce isolated colonies on or within agar.
3. Consider the streak plate technique: This method spreads bacteria on the surface of the agar to obtain isolated colonies only on the surface, not within the agar.
4. Consider the spread plate technique: This involves spreading a diluted sample on the surface of the agar, resulting in isolated colonies only on the surface.
5. Consider the pour plate technique: This involves mixing the diluted sample with molten agar and then pouring it into a petri dish, which allows colonies to grow both within the agar and on its surface, leading to isolated colonies in both locations.