Microbiological Streaking

Streaking is a technique used in Microbiology, to isolate a pure strain (genetic variant, subtype or culture) within a single species of microorganism. This is done by taking a larger concentration of bacteria and diluting it to a smaller concentration.

There are a few methods to achieve this: the T-streak method, the Quadrant method and the Discontinuous streaking method. All methods require certain tools including a sterile tool to do the streaking such as a cotton swab or inoculation loop, agar plate, bunsen burner, and depending on the strain of bacteria, the sample may need an incubator for 24-36 hours.

The procedure for streaking is as follows:

1. the inoculation loop is put through a flame to make it sterile and then when cooled dipped in the patient specimen.
2. The loop is dragged across the agar in a zigzag motion so approximately 30% of it is covered.
3. The loop is re-sterilized and then dragged across the plate in the previously streaked section 2-3 times in the zigzag pattern.
4. Repeat one more time.

In industrial settings automated equipment is sometimes used for streaking for accurately faster work and to achieve better consistency of streaking.

Wikipedia: Streaking (microbiology)

Microbenotes: Streak plate method