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Name: Jacqueline L.
Status: Student
Age: 18
Location: N/A
Country: N/A
Date: June 2003

In testing out certain types of sunscreen, why do lab experiments used the e. coli strain K12 to grow on agar surface i.e. the petri dish, to demonstrate the effects of the sun on human skin cells?

E. coli K-12 is probably susceptible to UV damage. When susceptible bacteria are exposed to UV light, it damages their DNA and since they are unicellular, this is obvious sooner than UV damage in a multicellular organism. Even though it is not exactly applicable to humans, this system can be used to COMPARE the effectiveness of sunscreens on this organism.


I do not believe that any bacterial system can come close to modeling sun screen protection in humans. It is also interesting to note that as of last year it is not certain that sun screens even work to prevent melanoma. There is also mounting evidence that melanoma is caused in at least some cases by the melanin molecule's post UV action on DNA.

Peter Faletra

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