{"id":168534,"date":"2025-10-06T07:23:00","date_gmt":"2025-10-06T05:23:00","guid":{"rendered":"https:\/\/renewable-carbon.eu\/news\/?p=168534"},"modified":"2025-09-30T13:45:44","modified_gmt":"2025-09-30T11:45:44","slug":"biological-upcycling-of-polystyrene-into-ready-to-use-plastic-monomers-and-plastics-using-metabolically-engineered-pseudomonas-putida","status":"publish","type":"post","link":"https:\/\/renewable-carbon.eu\/news\/biological-upcycling-of-polystyrene-into-ready-to-use-plastic-monomers-and-plastics-using-metabolically-engineered-pseudomonas-putida\/","title":{"rendered":"Biological upcycling of polystyrene into ready-to-use plastic monomers and plastics using metabolically engineered\u00a0Pseudomonas putida"},"content":{"rendered":"\n\n\n

The persistent accumulation of plastic waste, particularly polystyrene (PS), poses significant environmental challenges because of its extensive use and low recycling rates. Addressing these challenges necessitates innovative and sustainable solutions. This study presents a strategy to upcycle PS waste into valuable chemical products, including adipic acid, hexanediol, hexamethylenediamine, and nylon-6,6, using metabolically engineered Pseudomonas putida<\/em> KT2440. <\/p>\n\n\n\n

This process involves the photolytic degradation of PS into benzoic acid, followed by microbial conversion into cis, cis<\/em>-muconate (MA) and chemical synthesis of the final products. The engineered strains withstood 30\u202fmM concentrations of PS-derived aromatics and converted them stoichiometrically into MA in the presence of glucose as a growth substrate. 13<\/sup>C metabolic flux analysis revealed energy and redox limitations in the presence of 25\u202fmM benzoate and 300\u202fmM MA. The cells responded to stress by enhancing the flux for periplasmic glucose oxidation and fluxes through the NADPH-forming dehydrogenases; this process caused more than 40% glucose\u2011carbon loss into byproducts. Fine-tuned dynamic glucose and benzoate feeding enabled high-level MA production. Energy-optimized genome-reduced strains were used to increase carbon efficiency. A final MA titer of over 65\u202fg\u202fL\u22121<\/sup> was achieved in fed-batch fermentation. <\/p>\n\n\n\n

This process was demonstrated using the glucose derived from a viscose textile waste blend as the growth substrate and resulted in fully waste-based products. The resulting adipic acid and hexamethylenediamine were polymerized into nylon-6,6 with properties comparable to those of petrochemical-derived polymers, revealing a sustainable pathway for PS upcycling. This research provides a proof-of-concept for bacterial upgrading of PS-derived substrates and a viable method for managing plastic waste and producing valuable chemical products.<\/p>\n\n\n

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1. Introduction<\/h3>\n\n\n\n

Plastic accumulation poses a persistent global challenge [1<\/a>]. Polystyrene (PS), widely used in packaging and single-use goods, is a major contributor to plastic waste and microplastic pollution [2<\/a>]. Despite >20 Mt. annual PS production [3<\/a>], recycling remains <10\u202f% due to economic and technical barriers [4<\/a>], Prior efforts have focused on depolymerizing PS to aromatic monomers for recovery and reuse [[5]<\/a>, [6]<\/a>, [7]<\/a>, [8]<\/a>, [9]<\/a>, [10]<\/a>], but end-to-end routes that convert PS into drop-in polymer precursors and validate final polymer performance remain scarce.<\/p>\n\n\n\n

This work introduces a fully integrated, waste-based value chain from PS to nylon-6,6, combining (i) photolytic depolymerization of PS to benzoate using mild conditions, (ii) microbial upgrading by metabolically engineered Pseudomonas putida<\/em> to produce cis,cis-muconic acid (MA), and (iii) chemical transformations of MA to adipic acid, hexanediol, and hexamethylenediamine, culminating in nylon-6,6 with petrochemical-equivalent properties. The process further leverages textile-derived glucose as a growth substrate, enabling a dual-waste, fully waste-based concept. At the bioprocess core, we deploy a precision fermentation strategy guided by 13<\/sup>C metabolic flux analysis, using dynamic glucose dosing and DO-coupled benzoate feeding to sustain productivity under substrate\/product stress. We also evaluate a genome-reduced chassis for improved carbon efficiency and robustness.<\/p>\n\n\n\n

P. putida<\/em> is a versatile host with broad aromatic catabolism and industrial robustness [[11]<\/a>, [12]<\/a>, [13]<\/a>, [14]<\/a>, [15]<\/a>, [16]<\/a>]. Through pathway engineering, it efficiently channels aromatics to MA, a valuable platform chemical [[17]<\/a>, [18]<\/a>, [19]<\/a>, [20]<\/a>, [21]<\/a>], and synthetic biology has broadened its repertoire to additional products [[22]<\/a>, [23]<\/a>, [24]<\/a>, [25]<\/a>]. What distinguishes this study is the system-level integration: we (i) convert PS directly to a fermentable intermediate (benzoate), (ii) demonstrate high-efficiency microbial upgrading of both commercial and crude PS-derived benzoate, (iii) replace virgin sugar with textile-derived glucose, and (iv) close the loop to nylon-6,6, confirming material parity. The combined flux-guided control and waste-only feedstocks address key roadblocks in PS valorization\u2014namely, inhibitory aromatic stress, by-product formation, and dependency on virgin substrates.<\/p>\n\n\n\n

In summary, this study delivers a novel, end-to-end, fully waste-based route from PS to adipic acid, 1,6-hexanediol, 1,6-hexamethylendiamine, and nylon-6,6 by integrating gentle photochemical depolymerization, engineered microbial conversion, and industrial-relevant downstream chemistry, underpinned by quantitative flux analysis and dynamic process control. This framework advances PS upcycling beyond monomer recovery toward specification-grade polymer precursors and materials, offering a practical pathway for circular manufacturing.<\/p>\n\n\n\n

2. Materials and methods<\/h3>\n\n\n\n

…<\/p>\n\n\n\n

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you may read the complete article under https:\/\/www.sciencedirect.com\/science\/article\/pii\/S1385894725092733<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

The persistent accumulation of plastic waste, particularly polystyrene (PS), poses significant environmental challenges because of its extensive use and low recycling rates. Addressing these challenges necessitates innovative and sustainable solutions. This study presents a strategy to upcycle PS waste into valuable chemical products, including adipic acid, hexanediol, hexamethylenediamine, and nylon-6,6, using metabolically engineered Pseudomonas putida KT2440. This […]<\/p>\n","protected":false},"author":59,"featured_media":168548,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_seopress_robots_primary_cat":"none","nova_meta_subtitle":"This study presents a strategy to upcycle PS waste into valuable chemical products, using metabolically engineered\u00a0Pseudomonas putida\u00a0KT2440","footnotes":""},"categories":[17143],"tags":[6843,14543,5796,10416,12615,23180,14462,17151,10453],"supplier":[6482,2592,536,835],"class_list":["post-168534","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-recycling","tag-biochemicals","tag-bionylon","tag-biotechnology","tag-circulareconomy","tag-microbes","tag-packagingwaste","tag-plasticwaste","tag-polystyrene","tag-recycling","supplier-leibniz-institut-materialien","supplier-taros-chemicals-gmbh-co-kg","supplier-universitaet-saarland","supplier-universitaet-fuer-bodenkultur-wien-boku"],"_links":{"self":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/posts\/168534","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/users\/59"}],"replies":[{"embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/comments?post=168534"}],"version-history":[{"count":0,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/posts\/168534\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/media\/168548"}],"wp:attachment":[{"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/media?parent=168534"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/categories?post=168534"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/tags?post=168534"},{"taxonomy":"supplier","embeddable":true,"href":"https:\/\/renewable-carbon.eu\/news\/wp-json\/wp\/v2\/supplier?post=168534"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}