Extracellular degradation of a polyurethane oligomer involving outer membrane vesicles and further insights on the degradation of 2,4-diaminotoluene in Pseudomonas capeferrum TDA1

Òscar Puiggené,Uwe Kappelmeyer,Stephan Schreiber,Daniel Wibberg,Stephan Thies,Dietmar Schlosser,María José Cárdenas Espinosa,Hauke Harms,Nico Jehmlich,Hermann J Heipieper,Christian Eberlein,Joern Kalinowski

doi:10.1038/s41598-022-06558-0

Abstract

The continuing reports of plastic pollution in various ecosystems highlight the threat posed by the ever-increasing consumption of synthetic polymers. Therefore, Pseudomonas capeferrum TDA1, a strain recently isolated from a plastic dump site, was examined further regarding its ability to degrade polyurethane (PU) compounds. The previously reported degradation pathway for 2,4-toluene diamine, a precursor and degradation intermediate of PU, could be confirmed by RNA-seq in this organism. In addition, different cell fractions of cells grown on a PU oligomer were tested for extracellular hydrolytic activity using a standard assay. Strikingly, purified outer membrane vesicles (OMV) of P. capeferrum TDA1 grown on a PU oligomer showed higher esterase activity than cell pellets. Hydrolases in the OMV fraction possibly involved in extracellular PU degradation were identified by mass spectrometry. On this basis, we propose a model for extracellular degradation of polyester-based PUs by P. capeferrum TDA1 involving the role of OMVs in synthetic polymer degradation.

Highlights

The continuing reports of plastic pollution in various ecosystems highlight the threat posed by the ever-increasing consumption of synthetic polymers
TDA1 and WCS358 can be found in the same species cluster and differ significantly from the P. putida type species
Further insights and proof regarding the mentioned metabolic pathway in P. capeferrum TDA1 are provided from transcriptomic data

Summary

Introduction

The continuing reports of plastic pollution in various ecosystems highlight the threat posed by the ever-increasing consumption of synthetic polymers. The resulting broad range of materials has applications in many sectors, such as building and construction, furniture production, automotive or medical devices, due to its excellent mechanical properties, stability and enhanced biocompatibility[4].The high polyurethane demand generates significant amounts of waste globally, of which only 29.7% is recycled, 30.8% is disposed in landfills and 39.5% is recuperated through energy recovery[5,6]. OMVs harbor active enzymes and extracellular structures were reported to exhibit catabolic activity in different bacteria (Pseudomonas, Rhodoccocus, Amycolatopsis and Delftia) grown on aromatic substrates such as phenanthrene and lignin-rich m edia[20,21]. Resilient plastics such as polyethylene (PE) and polystyrene (PS) strongly depend on the formation of a biofilm in order to increase the surface interactions with bacterial c ells[22,23]. Other strains such as Bacillus sp. grown on PS films presented a reduced polymer mass by 23% after 14 d ays[25]

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Conclusion