A Different Kind of Secret Code

Researchers have invented a new form of secret messaging using bacteria that make glowing proteins only under certain conditions. In addition to being useful to spies, the new technique could also allow companies to encode secret identifiers into crops, seeds, or other living commodities.

The new glowing bacteria actually did grow out of a bit of cloak-and-dagger thinking. Several years ago, the Defense Advanced Research Projects Agency asked researchers to submit ideas for ways to encode secret messages without the need for electronics. At the time David Walt, a chemist at Tufts University in Medford, Massachusetts, teamed up with his former adviser George Whitesides, a chemist at Harvard University. Together, they came up with a way to add a variety of metal salts to a fuse that, when lit, would give off a sequence of pulses of infrared light that encoded a message. That got them thinking about other ways to accomplish the same thing. And so last year they decided to try something else, using bacteria to encode their secrets.

The new scheme replaces the fuse with seven colonies of Escherichia coli bacteria, each given a gene for a different fluorescent protein. When, and only when, these genes are turned on do the bacteria make these proteins and light up. The colors, including yellow, green, and red, vary based on which gene is expressed. All are clearly visibly different to the naked eye. With their colorful bacterial colonies in hand, the researchers then created a code using pairs of different colored bacteria. Having seven colors gave them 49 combinations, which they used to encode the 26 different letters and 23 alphanumeric symbols such as "@" and "$." They wrote a message by simply blotting pairs of colored bacteria in rows. To "print" the message, the researchers transferred the bacteria onto a plate containing agar, a bacterial growth medium, into which they pressed a sheet of nitrocellulose "paper" that immobilizes the bacteria.

At this point, the bacteria on the nitrocellulose paper remain invisible. But the message receiver can turn on the key genes and make the colors light up by pressing the nitrocellulose paper into an agar plate containing a chemical trigger that activates expression of the fluorescent proteins. (The proteins chosen to light up are ones the bacteria don't normally use, so unless the researchers activate them, they stay quiescent.) As long as the receiver knows which colors correspond to which characters, the message is revealed. But Walt and his colleagues added one more safeguard as well. Into some bacteria they inserted genes for resistance to particular antibiotics; the idea is that only the antibiotic-resistant bacteria are carrying the real message. If the message fell into the wrong hands, the receiver would see a mix of colors once the genes were activated and be unable to read it. But if the decoder added the right antibiotic, nonresistant bacteria and their colors die away, and the message becomes clear. The first example, reported in today's issue of the Proceedings of the National Academy of Sciences reads "this is a bioencoded message from the walt lab @ tufts university 2010."

A Different Kind of Secret Code

The nerd in me says, "Cool!"

The other part of me says, well, I'm sure your mind has wandered while you've been reading this, as well...

My concerns run to this. Theres a serious terror threat to some town or city. An agent of a nation opposed to such actions encodes a corn on the cob and sends it to his contact. His contact mistakes it for lunch, and not only gets ill, but eats the only warning the free world might get about a catastrophy.

I'm more concerned at the insertions of genes to cause certain bacteria to be resistant to antibiotics frankly.

Personally, i think the idea is a bad one, primarily because of the GM bacteria being created to be resistant to AB's, but because bacteria can be copied, genetic / gene adapted ones too..all an enemy would need to do would be to make multiple copies of the coded message and try just about every antibiotic under the sun...they'd get lucky eventually, and be able to read the message.

reply to post by spikey



That's what stood out to me, as well.

Is this way of encoding messages really practical? Or safe?

If they're actually planning on putting this to use, there's a whole lot of things they need to consider first. Heck, maybe this has already been put to use, as far as we know... or will ever know.

Finally I have the answer to the mystery that was contained in my first post to ATS, which was this:

What did Mossad replace their numbers stations with, when they all suddenly went offline last March?