“In the laboratory, a sterile inoculating loop is moved across the agar surface in a culture dish, thinning a sample and isolating individuals.” This statement describes which of the following?
a. Broth culture
b. Pour plate
c. Streak plate
d. Dilution plate

Verified step by step guidance

1. Step 1: Understand the context of the problem, which involves using a sterile inoculating loop to spread microorganisms on an agar surface in a culture dish.
2. Step 2: Recall the definitions of the options: a broth culture is a liquid medium, a pour plate involves mixing bacteria with molten agar before solidifying, a streak plate involves spreading bacteria on the surface of agar to isolate individual colonies, and a dilution plate involves serial dilutions before plating.
3. Step 3: Identify that the process described involves moving the loop across the agar surface to thin out the sample and isolate individual colonies, which matches the streak plate technique.
4. Step 4: Confirm that the streak plate method is specifically designed to separate individual bacterial cells on the agar surface to obtain isolated colonies.
5. Step 5: Conclude that the correct description corresponds to option c, the streak plate method.

Key Concepts

Streak Plate Technique

The streak plate method is a microbiological technique used to isolate individual bacterial colonies by spreading a sample over the surface of an agar plate with a sterile loop. This thins out the sample, allowing single cells to grow into separate colonies for identification.

Agar Culture Media

Agar is a gelatinous substance derived from seaweed used as a solid culture medium in petri dishes. It provides a surface for microbial growth and allows for the physical separation of colonies during techniques like streak plating.

Colony Isolation

Colony isolation is the process of separating individual microbial cells on a solid medium so that they grow into distinct colonies. This is essential for obtaining pure cultures and studying specific microorganisms without contamination.