Final answer:
The three basic methods for separating cells on a plate include the streak plate, spread plate, and pour plate methods. Each method utilizes a different technique to distribute and isolate microorganisms for growth into visible colonies.
Step-by-step explanation:
To isolate and identify microorganisms, it's essential to separate cells in a mixed culture. Here are three methods commonly used:
Streak Plate Method
The streak plate method involves spreading a diluted sample of bacteria across an agar surface to form isolated colonies. A sterile tool is used to 'streak' the sample in a systematic pattern, resulting in progressively fewer cells being distributed. As these cells grow, they form visible separate colonies.
Spread Plate Method
The spread plate method requires placing a small volume of a diluted sample on the agar surface and spreading it over the surface evenly using a sterile spreader. This ensures that the bacteria are sufficiently separated to form individual colonies upon incubation.
Pour Plate Method
In the pour plate method, a sample is mixed with liquid agar and poured into a sterile Petri dish, which is then swirled to mix. This technique allows for separation and counting of colonies formed by bacteria within the agar as well as on the surface.