What are the purposes of the streak plate method?

The main purpose of the streak plate is to obtain isolated colonies or bacteria from a mixture by using a simple mechanical process. This technique allows for the separation and growth of individual bacterial colonies on agar plates for research on the bacteria in isolation. Additionally, the streak plate method helps to estimate the number of viable bacteria in a sample. 

Isolated colonies are groups of cells which originate from a single parent cell. Each colony originates from a single initial cell which underwent division to form a visible cluster on the agar plate. To accurately study and identify their specific features including size, shape, texture, color, and surface appearance, individual colonies must be sufficiently separated from one another on the agar plate. This isolation allows for the clear observation and examination of each colony’s characteristics. Thus, the streak plate method makes these observations possible.