Industrial Biotechnology for Sustainable Plastics: From Bio-Based Synthesis and Enzymatic Recycling to Polyhydroxyalkanoate Upcycling

BackgroundPetroleum-based plastics remain one of the defining environmental problems of our time, and industrial biotechnology offers a coherent, circular answer: producing bio-based polymers from renewable and waste carbon, and recovering the carbon locked in plastic waste through biological routes. Polyhydroxyalkanoates (PHAs) — biodegradable, biocompatible microbial polyesters — sit at the centre of this vision. On the front end, metabolic engineering, synthetic biology and enzyme engineering are expanding the microbial hosts, feedstocks and biocatalysts available for efficient, cost-competitive PHA synthesis and for the conversion of lignocellulosic and industrial residues. On the back end, engineered enzymes enable the depolymerisation and recycling of synthetic plastics, whose products can be upcycled into new PHAs and value-added biopolymers. Because microbial metabolism, substrate choice and bioprocess conditions govern PHA composition — and thereby the mechanical, thermal and functional performance of the material — connecting sustainable bioproduction with rational material design is now essential to next-generation, circular plastics.GoalThis Research Topic reframes plastic waste and renewable biomass as feedstocks for a circular, biocatalyst-centred plastics economy, with PHAs as the unifying product. Despite significant progress, two coupled bottlenecks persist: making bio-based production and enzymatic recycling economically competitive, and obtaining polymers whose properties meet real industrial requirements. On the production side, advances in metabolic engineering, synthetic biology, systems biotechnology, enzyme mining and bioprocess optimisation make it possible to direct carbon fluxes toward tailor-made PHAs — from rigid short-chain-length (scl) polymers to flexible, elastomeric medium-chain-length (mcl) PHAs — from renewable feedstocks, industrial by-products and waste streams. On the circularity side, robust enzymes and microbial systems can depolymerise recalcitrant plastics and redirect the released carbon into PHAs and other biopolymers. Equally central is the material dimension: how polymer composition and structure translate into properties, and how functionalisation, blending and processing expand application potential. By connecting microbial and enzyme engineering, bioprocess development, polymer functionalisation and application-oriented research, this collection seeks to consolidate innovative pathways that link sustainable bioproduction with high-performance materials, advancing next-generation, circular PHA technologies within industrial biotechnology.Scope and Information for AuthorsWe welcome high-quality contributions that connect sustainable PHA bioproduction with material design across the full plastics life cycle — from bio-based synthesis and enzyme-driven recycling to the upcycling of waste carbon into high-performance biopolymers. Themes of interest include, but are not limited to:• Metabolic engineering and synthetic biology strategies for PHA production;• Engineering of microbial cell factories and mixed microbial cultures;• Sustainable PHA production from renewable feedstocks, lignocellulosic biomass, industrial by-products and waste streams;• Enzyme mining and protein engineering for PHA biosynthesis and for enzymatic depolymerisation and recycling of synthetic plastics;• Bioprocess optimisation, scale-up, bioelectrochemical strategies and digital tools (AI/ML, digital twins) for process improvement;• Tailoring PHA composition and structure to achieve specific material properties, including scl- and mcl-PHA structure–property relationships;• Polymer functionalisation, modification, blending, extraction/recovery and processing technologies;• Biological upcycling of plastic- and waste-derived carbon into PHAs and value-added biopolymers, and biodegradation and recycling of PHA-based materials;• Advanced and emerging applications of PHAs across industrial sectors.Contributions integrating biotechnology, process engineering and material performance are particularly encouraged. Topic editors: Hossain M. Zabed, Alejandro Chamizo Ampudia, Silvia González-Rojo, Qi Xianghui Source: https://www.frontiersin.org/research-topics/85988/industrial-biotechnology-for-sustainable-plastics-from-bio-based-synthesis-and-enzymatic-recycling-to-polyhydroxyalkanoate-upcycling