Microbial Computers Could Revolutionize Medical Diagnostics

Source: http://stanmed.stanford.edu/2013fall/article10.html Imagine going to your doctor for a routine physical examination.  At some point your physician asks you to imbibe some exotic concoction.  A few hours later, you have a bowel movement: one that your doctor collects and shines ultraviolet light upon.  He’s looking for your solid waste material to shine back at him; you are praying it doesn’t, because a glow means your body is now a host to cancer. Such a technique isn’t part of the normal battery of tests people are typically given during a physical—at least, not yet.  It may be in the not-too-distant future, however, because of research being led by Drew Endy, an assistant professor of bioengineering, and a team of researchers at Stanford University.  Endy and his colleagues have taken the humble and ubiquitous E. coli bacteria – easily the most studied and scrutinized germ in the world – and turned it into a biological computer; one with all of the classic functions of any other number-cruncher, although on a drastically smaller scale. Using genetic engineering, Endy and his team gave E. coli the ability to use logic, to store information and then to transmit that information.  Furthermore, it does so using standard binary code.  However, rather than using transistors to process, hold and then pass along information, the modified E.coli uses enzymes to make changes according to a genetically “programmed” set of instructions. The E. coli could further be altered to react in the presence of cancer cells.  Upon detection of the cancerous tissue, the bacteria flips a logic gate and generates a package of protein – much like a packet of digital information to be sent across the Internet via internet protocol (IP) – that is then passed along to other modified E. coli.  This information signals the bacteria to generate the requisite proteins for ultraviolet illumination.  Then, after the bacteria have exited the body in the normal process of waste excretion, shining UV light on the expelled mass will cause the now-sensitized microbes to “reflect”.  The greater the amount of UV illumination the higher the likelihood that the patient has cancer.  The benefits of such a scheme are numerous: fast and effective visual determination of cancer and a far more thorough physical examination not possible with current medical techniques. However, there also exists the potential to turn these “biological computers” into something far more proactive.  One possibility is to program the bacteria to generate insulin in the presence of sugar: a boon to diabetics.  Arthritis sufferers might benefit from E. coli that detect pain in a given location and respond by producing capsaicin (the chemical that gives spicy food its “heat”) to reduce pain and remove such inhibition to motor use. It is looking as though it will be quite some time before the work of the Stanford team becomes mainstream technology.  Much more research and experimentation is required, to say nothing of official review and approval for use in humans.  Even so, it is possible that computing has turned a page and that in years to come, Drew Endy and his team will be hailed for a scientific breakthrough as revolutionary as the transistor itself.