Degradation of recalcitrant polyurethane and xenobiotic additives by a selected landfill microbial community and its biodegradative potential revealed by proximity ligation-based metagenomic analysis

Abstract

Polyurethanes (PU) are the sixth more produced plastics with around 19-million tons/year, but since they are not recyclable they are burned or landfilled, generating ecological damage. To elucidate the mechanisms that landfill microbial communities perform to attack recalcitrant PU plastic, we studied the BP8 community selected by its capability to grow in a water PU dispersion (WPUD) that contains a polyether-polyurethane-acrylate (PE-PU-A) copolymer and xenobiotic additives (N-methyl 2-pyrrolidone, isopropanol and glycol ethers), and performed a proximity ligation-based metagenomic analysis for revealing the community structure and potential biodegradative capacity. Additives were consumed early whereas the copolymer was cleaved throughout the 25-days incubation. BP8 metagenomic deconvolution reconstructed five genomes, three of them from novel species. Genes encoding enzymes for additives biodegradation were predicted. The chemical and physical analysis of the biodegradation process, and the identified biodegradation products show that BP8 cleaves esters, aromatic urethanes, C-C and ether groups by hydrolytic and oxidative mechanisms. The metagenomic analysis allowed to predicting comprehensive metabolic pathways and enzymes that explain the observed PU biodegradation. This is the first study revealing the metabolic potential of a landfill microbial community that thrives within a WPUD system and shows potential for bioremediation of polyurethane- and xenobiotic additives-contaminated sites.