Forget dyeing with cabbage, dirt, or even airborne pollution. If you want to raise eyebrows, do as Natsai Audrey Chieza does and dabble in living—albeit nonpathogenic—Streptomyces bacteria, commonly found in soil. The London-based "design futurist" is the prime mover behind "Faber Futures," the first line of screen-printed textiles to use microbes as dye machinery. Together with University College London's John Ward, Chieza "trains" bacteria to create a range of pigments as a byproduct of their metabolic activity. The trick, Chieza says, is to manipulate the composition of their nutrition. Organisms cultured from the roots of tarragon, for instance, create different results than inoculations from rosemary or mint. Changes in incubation temperature, pH levels, and growth period can also generate shifts in hue.