BRAINCAKEGrowing a Pure Culture
A pure culture contains only one species (or strain) of microorganism. Pure cultures are needed to identify a microorganism, to test it with antibiotics, or to use it in industry, because a contaminant would give misleading results.
The usual method is the streak plate, which thins out the cells so that some grow as separate colonies:
1. Using aseptic technique, flame an inoculating loop, let it cool and dip it into the mixed culture.
2. Streak the loop in a zigzag across one edge of an agar plate (section 1).
3. Flame and cool the loop. Drag it once through the end of section 1 and streak a new zigzag in section 2.
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Key terms in this lesson
- strain
- A genetically distinct variant within a species, such as a bacterium, that differs slightly from other members of the species.
More in Bacteria and Disease
- Culturing Microorganisms
- Aseptic Culture Techniques
- Selective Media
- Counting the Number of Cells
- Turbidity
- Dilution Plating
- Area and Mass of Fungi
- Growth of Bacterial Colonies
All 30 lessons in Bacteria and Disease · All Edexcel A-level Biology topics