Open Question
A student observes a researcher streaking a plate numerous times, flaming the loop between streaks. The researcher is likely using the ___________ method to isolate microorganisms.
10. Dynamics of Microbial Growth
Plating Methods
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Which plating method can be used to isolate a species of bacteria from a mixed culture of cells?
A
Pour-plate method.
B
Streak-plate method.
C
Spread-plate method.
D
All methods can be used.
Verified step by step guidance1
Understand the goal: The objective is to isolate a single species of bacteria from a mixed culture. This means you need a method that allows individual colonies to grow separately.
Consider the streak-plate method: This technique involves spreading a loopful of the mixed culture over the surface of an agar plate in a pattern that thins out the bacteria, ideally leading to isolated colonies.
Evaluate the pour-plate method: This method involves mixing the bacteria with molten agar and pouring it into a petri dish. It is less effective for isolation because bacteria are embedded in the agar, making it harder to obtain isolated colonies.
Assess the spread-plate method: This involves spreading a diluted sample over the surface of an agar plate. While it can lead to isolated colonies, it is generally less effective than the streak-plate method for achieving isolation from a mixed culture.
Conclude with the most effective method: The streak-plate method is typically the best choice for isolating a single species from a mixed culture because it allows for the separation of individual colonies on the surface of the agar.
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