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Name: Carolyn M McPherson
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Question:
I am a teacher seeking information for one of my students who is interested in researching lactose intolerance. She wishes to test bacteria (E. coli have been suggested) for intolerance. Is there a procedure for doing this? Do you have other suggestions or advice? This student is a high school sophomore.


Replies:
Yes there is a way to find E coli that can't metabolize lactose. In fact, it's one of the most commonly used methods in molecular biology. A colorless chemical (called X-Gal for short) turns blue if the bacterium can metabolize lactose, and stays clear otherwise. SO, if we have X-gal in the agar plate, and streak out the bacteria, the WHITE colonies are lactose-intolerant!
I don't know for sure, but I will bet that most of the usual supply houses can provide a kit for this purpose.

Steve J Triezenberg


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