 Previous research indicated that both Rre37 and SigE proteins are separately responsible for the activation of PHB production in the "Synechocystis" strain of cyanobacteria.Thus, in this study, the "Synechocystis" strain was modified to overexpress Rre37 and SigE proteins together under nitrogen-limited conditions.Currently, a student-run research group at the University of Virginia (Virginia iGEM 2019) is in the process of genetically engineering "Escherichia coli" to convert styrene (monomer of polystyrene) into P3HBs (a type of PHA).