Question

1. What is the significance of producing isolated bacterial colonies on an agar plate?

2. Briefly, explain how the formation of a bacterial colony occurs on an agar plate.

3. Why must you flame the loop between each streak when performing the streak plate techniques?

4. How can you determine whether a culture that you have been provided with is a "pure" culture?

5. You streak a culture and find that the colonies in Quadrant 4 are larger in diameter than the colonies in Quadrant 2. Why might this be?

Answer 1

Ans 1) The significance of producing isolated bacterial colonies on agar plate is that it helps to isolate and pick a single type of bacteria. The streak plate can be done on the agar plates and it can be efficiently only spread on the surface of the agar plate and hence single colonies can be isolated and separated. It helps in extracting out and finding single and individual cells.

Ans 2) The bacterial colonies are incubated or cultivated on the agar plate with nutrients and medium using a streak plate method. As the appropriate condition is given, the bacteria starts consuming the nutrients and hence starts growing and multiplying. The colonies mostly start from one cells and forms a pile of billions of cells through rapid growth and multiplication.

Ans 3) The loop must be flamed between each streak to prevent microbial contamination. When a microbial streak is performed it consists of the microbes and hence it might lead to contaminating the culture. By flaming it and turning it red hot, the microbes are killed and hence the growth of unwanted bacteria can be stopped and hence contamination can be prevented.