P123: Regulation of the Polyurethanase Activity in Pseudomonas fluorescens Strain Pf-5

With the growing need of biodegradable and bio-resistant plastics it becomes increasingly important to understand the environmental conditions and mechanisms that lead to microbial degradation of synthetic polymers.  Several bacterial and fungal strains have been described that are able to degrade polyurethane.  Our goal is to identify and understand regulatory mechanisms that impact the secreted polyurethanase activity of Pseudomonas fluorescens. In initial experiments, we found that P. fluorescens strains ATCC 17571, PfO-1, and Pf-5 were able to degrade the polyester polyurethane Impranil® DLN in M9 agar plate clearing assays containing pyruvate as a carbon source. P. fluorescens strain Pf-5 was selected for further studies due to its relative fast polyurethane degradation ability and the availability of genome sequence data. We have examined the impact of different carbon sources on the polyurethanase activity in strain Pf-5. Polyurethane agar plate clearing assays showed that strain Pf-5 could grow in the presence of various carbon sources but that degradation of polyurethane occurred to different extents depending on the carbon source. We observed strong polyurethane degradation in the presence of citrate but severely reduced clearing of polyurethane when glucose was provided as a carbon source. Recent studies with liquid cultures of P. fluorescens Pf-5 revealed that the addition of polyurethane was not needed to obtain polyurethanase activity and confirmed decreased polyurethanase activity in the presence of glucose.