When attempting to isolate a specific type of bacteria from a clinical sample, this streak plate technique will need be repeated, possibly several times, in order to obtain a pure sample.
Again sterilize loop in flame of Bunsen burner or hub of microincinerator, and allow loop to cool.
Place loop in next quadrant of Petri dish, adjacent to quadrant #3. Gently drag the loop into quadrant #3 a few times, to obtain just a bit of bacteria from that sample, then spread that material over quadrant #4, in a back-and-forth "tornado" pattern.
Make sure that the quadrant #4 streak does not touch the quadrant #1 streak.
Incubate plate at 37 degrees C for at least 24 hours.
You have free access to a large collection of materials used in two college-level introductory microbiology courses (8-week & 16-week). The Virtual Microbiology Classroom provides a wide range of free educational resources including PowerPoint Lectures, Study Guides, Review Questions and Practice Test Questions.