Ting Lu of the University of Illinois at Urbana-Champaign, James Collins of the Massachusetts Institute of Technology, and colleagues designed two genetically engineered strains of the soil bacterium Pseudomonas putida to upcycle the most common plastic, polyethylene terephthalate. . Each strain breaks down one of two products (terephthalic acid and ethylene glycol) produced by the chemical breakdown of plastics.