Team:Austin Texas/human practices

From 2014.igem.org

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(Caffeinated Coli)
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[[file:UT_Austin_caffeine_growth_standard_curve.png‎|200px|thumb|right| Standard growth curve of knockout strain grown with different amounts of caffeine.]]
[[file:UT_Austin_caffeine_growth_standard_curve.png‎|200px|thumb|right| Standard growth curve of knockout strain grown with different amounts of caffeine.]]
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The E. coli we used were a modified knockout strain that could not synthesize guanine using its normal pathway, but had a plasmid introduced with a set of genes that allowed it to synthesize guanine from xanthine and many of its derivatives, including caffeine. Without caffeine (or certain other xanthine derivatives), the strain will not grow. When caffeine is added, the strain will grow normally until it runs out of caffeine, at which point it will stop growing. Thus, by looking at the relative growth of the strain with different samples of coffee and comparing it to a standard curve of growth in solutions with known amounts of caffeine, we could somewhat accurately measure the amount of caffeine in the coffee.  
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The E. coli we used are a synthetic strain, previously made by the 2012 UT Austin iGEM team '''[Link/Reference 2012 team page!]'''.  This strain lacks [...its normal guanine synthesis pathway], but contains a plasmid with a set of genes that enables the organism to synthesize guanine from xanthine and many of its derivatives, including caffeine. Without caffeine (or other xanthines), the strain cannot not grow. When caffeine is added, the strain grows normally until the caffeine is completely metabolized, at which point the cells can no longer synthesize guanine, and cease to grow. Thus, by looking at the relative growth of the strain with different samples of coffee and comparing it to a standard curve of growth in solutions with known amounts of caffeine, we could somewhat accurately measure the amount of caffeine in the coffee.  
[[file:UT_Austin_E._coli_coffee_cultures.jpg|300px|thumb|left| Cultures of knockout strain grown with collected coffee samples.]]
[[file:UT_Austin_E._coli_coffee_cultures.jpg|300px|thumb|left| Cultures of knockout strain grown with collected coffee samples.]]

Revision as of 21:09, 11 October 2014