Investigation of polyurethane degradation by biotechnological methods

Investigation of Polyurethane Degradation by Biotechnological Methods Management and recycling of plastic waste are one of the greatest challenges of the 21st century. Polyurethane (PU), in terms of production volumes, is the 5th plastic in Europe and the 7th in the world. To date, there is no recycling processes to integrate efficient reuse of polyurethane waste due to its high resilience and inefficient recycling methods. Therefore, new PU waste management solutions are being sought-after to stop the accumulation of polyurethane waste in landfills and its incineration. In order to create environmentally friendly technology, one of the studied methods of recycling polyurethane is biodegradation. Biodegradation is based on biotechnological methods during which the breakdown of polyurethane is performed by microorganisms and/or its secreted enzymes. The aim of the thesis is to investigate the degradation of polyurethane by biotechnological methods. During the study, the search for polyurethane-degrading microorganisms and their identification was carried out. The ability of commercial enzymes and recombinant urethanase to degrade polyurethane was also explored. During this study, eight bacterial strains capable of growing on polyether polyurethane and three – one bacterium and two fungi – degrading polyester polyurethane were isolated and identified according to the 16S rRNA and ITS gene regions. For the first time, Paenibacillus sp. and Stachybotrys sp. were identified as degrading polyester polyurethane. During the enzymatic degradation studies, GC analysis showed that the commercial lipases “Lipase LPS L”, “Lipolase 100 L” and “Novozyme 435” were able to depolymerise polyester polyurethane. Recombinant urethanase gene expression was performed in the E. coli BL21(DE3) strain. NDS-PAGE analysis revealed that the recombinant protein was localised in the insoluble proteins fraction. By changing the induction parameters (in performing gene expression at 1 mM IPTG concentration at 25 ºC for 18 hours), part of the recombinant protein was transferred to the soluble proteins fraction