Tuesday, October 18, 2011

A Different Kind of Secret Code

     Bacteria that express glowing proteins can also encode secret messages. Researchers led by David Walt, a chemist at Tufts University in Medford, Massachusetts, and George Whitesides, a chemist at Harvard University, gave each of seven colonies of Escherichia coli bacteria a gene for a different fluorescent protein. When these genes are turned on, the bacteria express their proteins and light up.
      The researchers then created a code using pairs of different colored bacteria (colors vary depending on which gene is expressed). With seven colors, they used the 49 possible combinations to encode the alphabet and 23 alphanumeric symbols. They wrote their message by blotting pairs of colored bacteria in a linear sequence.
      The bacteria, transferred onto nitrocellulose paper, remain invisible—until the message receiver presses the paper onto a bacterial growth medium containing a chemical trigger to activate the expression of the fl uorescent proteins. The first example, reported 26 September in the Proceedings of the National Academy of Sciences, reads “this is a bioencoded message from the walt lab @ tufts university 2010.



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