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.
The diverse benefits of synthetic polymers is overshadowed by the amount of plastic waste and its whereabouts. The problem can only be tackled by reducing and recycling of plastics. In this respect, investigating the (microbial) degradation of each type of polymer currently used may provide further understanding that fosters the development of new feasible recycling technologies. Here, we present a strategy to isolate bacteria from environmental samples that are able to degrade hydrolysis products and building blocks of polyurethane (PUR). Protocols are presented to enrich bacteria on the primary diamines 2,4-diaminotoluene (TDA) and 4,4'-diaminodiphenylmethane (MDA) as well as an oligomeric PUR (Sigma Aldrich, proprietary composition). For TDA and the oligomeric PUR, methods are suggested to monitor their concentration in bacterial enrichment cultures.
