This reminds me of the E.chromi scatalog: in 2009, the Cambridge iGEM team created a set of "color generator" biobricks that produced various pigments (carotenoids, melanin, violacein) [1], which led into a conceptual design project by Daisy Ginsberg and James King [2, 3]
The concept was that:
>The patient ingests a drink, much like a probiotic shake, laced with the engineered E. coli; the bacteria react with the enzymes, proteins, and other chemicals that are present in the gastrointestinal tract and turn different colors for different diseases, thus changing the color of the patient’s feces. [4]
The concept was that:
>The patient ingests a drink, much like a probiotic shake, laced with the engineered E. coli; the bacteria react with the enzymes, proteins, and other chemicals that are present in the gastrointestinal tract and turn different colors for different diseases, thus changing the color of the patient’s feces. [4]
[1]: http://2009.igem.org/Team:Cambridge/Project/Pigments
[2]: https://dublin.sciencegallery.com/growyourown/echromi
[3]: http://www.daisyginsberg.com/work/echromi-living-colour-from...
[4]: http://inhabitat.com/e-chromi-designer-bacteria-will-color-y...