Streak Plate of Legionella Public Health Image Library #7925

Streak Plate Technique for Isolating Bacteria - P2
Legionella sp. colonies cultivated on an agar plate and illuminated with ultraviolet light.

Isolation Streak Plate Technique
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.
Virtual Microbiology

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.
Prokaryotic Cell, Mariana Ruiz
​Page last updated: 11/2015
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Streak Plate Technique

More Streak Plate Resources
  • Bauman, R. (2004) Microbiology. Pearson Benjamin Cummings.

VIDEO: Isolation Streak Plate Technique
Printable Step-by-Step 
Isolation Streak Plate Procedure 
Free from the SPO 
Virtual Microbiology Classroom.

Streak plate of Micrococcus luteus