Plastic waste has become an increasingly prevalent environmental pollutant. This problem is exacerbated by the inability of plastic to degrade under most natural conditions. In contrast, polyhydroxyalkanoates (PHAs) are biologically produced, plastic-like polymers that can be broken down and metabolized by bacteria. The bacterium Streptomyces nymphaeiformis can degrade the PHA, polyhydroxybutrate (PHB), using an extracellular PHB depolymerase, which is encoded by the phaZ gene. PHB depolymerase is synthesized only in the presence of PHB or its monomer, but not glucose, suggesting that transcription of phaZ is regulated, presumably by transcriptional regulatory proteins that bind to its promoter region. The DNA base sequence of phaZ has previously been determined. In the predicted promoter region, there are sequences with homology to binding sites for known transcriptional regulators from other bacteria. A modified pull-down assay using streptavidin magnetic beads was evaluated for success in elucidating potential regulatory DNA-binding proteins for the phaZ gene. However, the method was unsuccessful
