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Streak Plate Technique for Isolating Bacteria - P2
Legionella sp. colonies cultivated on an agar plate and illuminated with ultraviolet light.
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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.
#1
#4
#3
#2
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.
Page last updated: 11/2015
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More Streak Plate Resources
- Bauman, R. (2004) Microbiology. Pearson Benjamin Cummings.
- Microbiology: Aseptic Technique, "Lab Notes" article from Science Prof Online.
- Streak Plate Procedure animated tutorial from Sinauer Associates.
- Streak Plate Interactive Animation from MSU. Test your skill to see if you can do a virtual streak plate procedure that produces isolated colonies.
VIDEO: Isolation Streak Plate Technique
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