Right now we have probiotic yogurt, but with genetically-engineered, color-changing bacteria, we may soon have diagnostic yogurt. I wonder who will be picked as the spokeswoman for that.
E. coli is a bacteria that no one wants on their spinach sandwich. E. chromi is the name given to a version of the bacteria that people may someday pay to have mixed in with their mayo. The parts of the bacteria which cause diarrhea, cramping, and vomiting have been removed. The ability to make and secrete certain pigments has been added. These bacteria are now ready to go to work. The bacteria can be used as biosensors to test air and water. When the bacteria are exposed to certain chemical elements, they secrete the pigment which corresponds to that element. Arsenic in the water, for example, will cause the bacteria to give off a blue color.
But sensing inorganic compounds in external elements is just a start. Researchers are hopeful that they'll be able to tailor the bacteria enough that they can be taken internally. Inside the body, biological changes cause different chemicals to be made. Ulcers, salmonella, and intestinal cancer all change the chemical make-up of the digestive system. If a person eats a mixture of these bacteria, and lets them grow inside their stomach and bowels, the presence of any medical problems could be quickly detected by the biosensors.
Depending on what chemicals are there, the biosensors would release different pigments. Although internal dye factories sound dangerous, there are plenty of natural pigments that the body tolerates. Lycopene is a pink-red pigment found in tomatoes. Caroteine is found in carrots. When the bacteria encounter enough of certain kinds of chemicals, they change color and secrete pigments in different combinations, which dyes everything that comes out of the stomach and makes its way down. That's right — people worried about illnesses will have to keep paint swatches in the bathroom. The exact pigmentation of waste products will let them know what to look for.