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 most produced plastics with around 18-million tons in 2016, but since they are not recyclable, they are burned or landfilled, generating damage to human health and ecosystems. To elucidate the mechanisms that landfill microbial communities perform to attack recalcitrant PU plastics, we studied the degradative activity of a mixed microbial culture, selected from a municipal landfill by its capability to grow in a water PU dispersion (WPUD) as the only carbon source, as a model for the BP8 landfill microbial community. The WPUD contains a polyether-polyurethane-acrylate (PE-PU-A) copolymer and xenobiotic additives (N-methylpyrrolidone, isopropanol and glycol ethers). To identify the changes that the BP8 microbial community culture generates to the WPUD additives and copolymer, we performed chemical and physical analyses of the biodegradation process during 25 days of cultivation. These analyses included Nuclear magnetic resonance, Fourier transform infrared spectroscopy, Thermogravimetry, Differential scanning calorimetry, Gel permeation chromatography, and Gas chromatography coupled to mass spectrometry techniques. Moreover, for revealing the BP8 community structure and its genetically encoded potential biodegradative capability we also performed a proximity ligation-based metagenomic analysis. The additives present in the WPUD were consumed early whereas the copolymer was cleaved throughout the 25-days of incubation. The analysis of the biodegradation process and the identified biodegradation products showed that BP8 cleaves esters, CC , and the recalcitrant aromatic urethanes and ether groups by hydrolytic and oxidative mechanisms, both in the soft and the hard segments of the copolymer. The proximity ligation-based metagenomic analysis allowed the reconstruction of five genomes, three of them from novel species. In the metagenome,

Strategic Approach Towards Plastic Waste Valorization: Challenges and Promising Chemical Upcycling Possibilities

“…[172] The global production rate of polyurethane is 17-18 million tons per annum. [173,174] These polymers are basically formed via a condensation reaction between methylene diphenyl diisocyanate (MDI) or toluene diisocyanate (TDI) and polyols. [175,176] The difference in properties of different varieties of PUs usually comes from the type of polyols and isocyanates used for the synthesis of PU polymers.…”

Hi-C deconvolution of a textile-dye degrader microbiome reveals novel taxonomic landscapes and link phenotypic potential to individual genomes

“…Around 13.4% of the raw genome clusters have > 50% completeness; about 29.9% of the clusters have between 20-48% completeness, and 56.7% of genome composites have less than 20% completeness. Remarkably, 98% of the clusters produced by Hi-C have less than 10% of gene marker overrepresentation and 63 effective clusters possess less than 5% according to CheckM [19], supporting that Hi-C method produces clusters with little contamination levels [11,12]. Forty-five clusters have a novelty score > 80% according to Mash distance metric [20] Subsequently, we applied Binner_refiner and DAS Tool overall 97 Hi-C assembly clusters to eliminate redundancy and generated more accurate genomes composites.…”

Current status on the biodegradability of acrylic polymers: microorganisms, enzymes and metabolic pathways involved

“…The identification of these genes suggests that some of the encoded proteins could be involved in AP biodegradation. Esterases and amidases would attack AP side groups, monooxygenases would activate the aliphatic acrylate chains (C-C backbone) by terminal or subterminal oxidations, and ADH and ALDH would generate intermediate compounds that can be channeled to α or β-oxidation (Gaytán et al 2020 ).…”