PMID- 34239864 OWN - NLM STAT- PubMed-not-MEDLINE LR - 20230920 IS - 2296-4185 (Print) IS - 2296-4185 (Electronic) IS - 2296-4185 (Linking) VI - 9 DP - 2021 TI - Progressing Plastics Circularity: A Review of Mechano-Biocatalytic Approaches for Waste Plastic (Re)valorization. PG - 696040 LID - 10.3389/fbioe.2021.696040 [doi] LID - 696040 AB - Inspirational concepts, and the transfer of analogs from natural biology to science and engineering, has produced many excellent technologies to date, spanning vaccines to modern architectural feats. This review highlights that answers to the pressing global petroleum-based plastic waste challenges, can be found within the mechanics and mechanisms natural ecosystems. Here, a suite of technological and engineering approaches, which can be implemented to operate in tandem with nature's prescription for regenerative material circularity, is presented as a route to plastics sustainability. A number of mechanical/green chemical (pre)treatment methodologies, which simulate natural weathering and arthropodal dismantling activities are reviewed, including: mechanical milling, reactive extrusion, ultrasonic-, UV- and degradation using supercritical CO(2). Akin to natural mechanical degradation, the purpose of the pretreatments is to render the plastic materials more amenable to microbial and biocatalytic activities, to yield effective depolymerization and (re)valorization. While biotechnological based degradation and depolymerization of both recalcitrant and bioplastics are at a relatively early stage of development, the potential for acceleration and expedition of valuable output monomers and oligomers yields is considerable. To date a limited number of independent mechano-green chemical approaches and a considerable and growing number of standalone enzymatic and microbial degradation studies have been reported. A convergent strategy, one which forges mechano-green chemical treatments together with the enzymatic and microbial actions, is largely lacking at this time. An overview of the reported microbial and enzymatic degradations of petroleum-based synthetic polymer plastics, specifically: low-density polyethylene (LDPE), high-density polyethylene (HDPE), polystyrene (PS), polyethylene terephthalate (PET), polyurethanes (PU) and polycaprolactone (PCL) and selected prevalent bio-based or bio-polymers [polylactic acid (PLA), polyhydroxyalkanoates (PHAs) and polybutylene succinate (PBS)], is detailed. The harvesting of depolymerization products to produce new materials and higher-value products is also a key endeavor in effectively completing the circle for plastics. Our challenge is now to effectively combine and conjugate the requisite cross disciplinary approaches and progress the essential science and engineering technologies to categorically complete the life-cycle for plastics. CI - Copyright (c) 2021 Nikolaivits, Pantelic, Azeem, Taxeidis, Babu, Topakas, Brennan Fournet and Nikodinovic-Runic. FAU - Nikolaivits, Efstratios AU - Nikolaivits E AD - Industrial Biotechnology & Biocatalysis Group, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens, Athens, Greece. FAU - Pantelic, Brana AU - Pantelic B AD - Eco-Biotechnology & Drug Development Group, Laboratory for Microbial Molecular Genetics and Ecology, Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Belgrade, Serbia. FAU - Azeem, Muhammad AU - Azeem M AD - Athlone Institute of Technology, Athlone, Ireland. FAU - Taxeidis, George AU - Taxeidis G AD - Industrial Biotechnology & Biocatalysis Group, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens, Athens, Greece. FAU - Babu, Ramesh AU - Babu R AD - AMBER Centre, CRANN Institute, School of Chemistry, Trinity College Dublin, Dublin, Ireland. FAU - Topakas, Evangelos AU - Topakas E AD - Industrial Biotechnology & Biocatalysis Group, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens, Athens, Greece. FAU - Brennan Fournet, Margaret AU - Brennan Fournet M AD - Athlone Institute of Technology, Athlone, Ireland. FAU - Nikodinovic-Runic, Jasmina AU - Nikodinovic-Runic J AD - Eco-Biotechnology & Drug Development Group, Laboratory for Microbial Molecular Genetics and Ecology, Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Belgrade, Serbia. LA - eng PT - Journal Article PT - Review DEP - 20210622 PL - Switzerland TA - Front Bioeng Biotechnol JT - Frontiers in bioengineering and biotechnology JID - 101632513 PMC - PMC8260098 OTO - NOTNLM OT - biodegradation OT - depolymerase OT - plastic waste OT - pretreatment OT - upcycling OT - valorization COIS- The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. EDAT- 2021/07/10 06:00 MHDA- 2021/07/10 06:01 PMCR- 2021/01/01 CRDT- 2021/07/09 07:01 PHST- 2021/04/16 00:00 [received] PHST- 2021/05/28 00:00 [accepted] PHST- 2021/07/09 07:01 [entrez] PHST- 2021/07/10 06:00 [pubmed] PHST- 2021/07/10 06:01 [medline] PHST- 2021/01/01 00:00 [pmc-release] AID - 10.3389/fbioe.2021.696040 [doi] PST - epublish SO - Front Bioeng Biotechnol. 2021 Jun 22;9:696040. doi: 10.3389/fbioe.2021.696040. eCollection 2021.