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Introduction to Circular Economy and Recycling Plastics
Published in Rupinder Singh, Ranvijay Kumar, Additive Manufacturing for Plastic Recycling, 2022
Deepika Kathuria, Monika Bhattu
Interestingly, scientists are working towards the development of methods for organic recycling of conventionally considered non-biodegradable plastics such as polyethylene and PET wastes as well. For example, Yoshida et al. identified the Ideonella sakaiensis strain 201‐F6 (a bacteria), which can utilize poly(ethylene terephthalate) (PET) for carbon and energy sources (Yoshida et al., 2016). Ideonella sakaiensis contains a plastic munching enzyme i.e. PETase and MHETase, which breaks PET into its building blocks such as terephthalic acid and ethylene glycol (Scheme 1.3), which can be utilized as building blocks for the preparation of PET. Many oxidoreductase have been shown to possess the capability to degrade PE. The development of engineered enzymes for plastic degradation can open up a new era for organic recycling of plastic wastes (Wei & Zimmermann, 2017). Recently, an engineered PET depolymerase enzyme has been reported with an improved ability of PET hydrolysis into its monomers (Austin et al., 2018 and Tournier et al., 2020).
Converting Petrochemical Plastic to Biodegradable Plastic
Published in Martin Koller, The Handbook of Polyhydroxyalkanoates, 2020
Tanja Narancic, Nick Weirckx, Si Liu, Kevin E. O’Connor
In 2016, Yoshida et al. reported the isolation of Ideonella sakaiensis 201-F6 with the unusual ability to degrade PET and assimilate its monomers [28]. The capacity of this bacterium for PET degradation is limited; it exhibits very slow degradation of a PET material with significantly lower crystallinity than PET used in packaging. The higher the crystallinity of PET, the more difficult it will be to degrade enzymatically. The key enzymes of I. sakaiensis involved in PET degradation, designated as PETase and MHETase [29–31], were characterized in detail and have great potential for further engineering for improved biocatalytic activity in plastic degradation [32].
Biotechnological Advancements in the Treatment of Plastic Wastes
Published in S Rangabhashiyam, V Ponnusami, Pardeep Singh, Biotechnological Approaches in Waste Management, 2023
Daniel Joe Dailin, Luo Zaini Mohd Izwan Low, Nurul Zahidah Nordin, Nur Izyan Wan Azelee, Shanmugaprakasham Selvamani, Vasantha M. Nayagam, Dayang Norulfairuz Abang Zaidel, Hesham Ali El Enshasy
The production of plastic-degrading enzymes is often reported at a minimal level by the native bacterium, in the natural environment. Recombinant DNA technology is used to overexpress the enzyme genes in another well-known cell, such as E. coli. This helped to evaluate the stability of the production of the enzyme. The shelf-life, substrate range, and physical parameters such as temperature and pH could be improved by the genetic engineering approach. Recombinant technology is also cost-effective as the purification of the enzymes is much easier compared to a native bacterium (Soe et al., 2019). The PET-degrading activity by Ideonella sakaiensis is well known and extensively studied since its discovery. Various recombinant studies involving PET hydrolases from I. sakaiensis have also been reported recently. Joo et al. (2018) performed pioneer works on heterologous expression of PET-ase in E. coli, to evaluate the molecular mechanism of plastic degradation. The recombinant study by Seo et al. (2019) improved several problems encountered during PET-ase expression in the native bacterium. Expression of Ideonella origin PET-ase gene into E. coli BL21 (DE3)-T1R improved the structural stability and solubility of the enzyme. The natural secretion of the enzymes by I. sakaiensis was found to have a limitation as the PET polymers were unable to penetrate membranes of Gram-negative bacteria. The study evaluated the fusion of E. coli Sec-dependent signal peptides with PET-ase gene to express the enzyme extracellularly. This study also had overcome the loss of enzyme activity which is often reported in continuous secretory production of recombinant enzymes (Soe et al., 2019).
In silico approach for identification of polyethylene terephthalate hydrolase (PETase)-like enzymes
Published in Bioremediation Journal, 2022
Poorvi Saini, Ananya Grewall, Sunila Hooda
Recently, PETase from proteobacteria Ideonella sakaiensis 201-F6 have been reported to have higher degradability and specificity than most of the other well characterized PET degrading enzymes known till then (Yoshida et al. 2016). IsPETase shared 51% amino acid sequence identity and catalytic residues with a hydrolase from T. fusca that also exhibit PET-hydrolytic activity. The enzyme shows high specificity to PET films, its heat labile but works well at low temperatures as compared to other enzymes (Yoshida et al. 2016). PET hydrolase upon degrading PET forms monomeric mono-2-hydroxyethyl terephthalate (MHET) which is a very minor component in the supernatant of I. sakaiensis cultured on PET film, indicating rapid MHET metabolism (Salvador et al. 2019; Sagong 2020). Another novel PET-degrading enzyme, RgPETase exhibiting almost similar level of PET-hydrolyzing activity at ambient temperature as shown by IsPETase has been reported by Sagong et al. 2021). RgPEtase is shown to have different behavior towards low crystalline PET. Several other PET hydrolytic enzymes have been confirmed to hydrolyze MHET and BHET from different microbial species like lipase from T. lanuginosus, cutinases from T. fusca, Fusarium solani (Eberl 2009), Penicillium citrinum (Liebminger et al. 2007) and T. alba (Ribitsch et al. 2012).
Microplastics pollution in Bangladesh: current scenario and future research perspective
Published in Chemistry and Ecology, 2020
Md. Ekramul Karim, Sohana Al Sanjee, Shohel Mahmud, Modhusudon Shaha, Md. Moniruzzaman, Keshob Chandra Das
Recently, scientists have engineered an enzyme, ‘PETase’ from a newly discovered bacterium, Ideonella sakaiensis 201-F6 which was able to grow on PET and utilise it as a major carbon and energy source for its growth [88]. The enzyme ‘PETase’ has the potential of breaking down millions of tons of plastic bottles which are made of PET and thus providing a potential solution to one of the world’s biggest environmental problems. Hence, the identification and use of microbes and their products such as enzymes to degrade and transform plastics as well as microplastics will enhance bioremediation processes without causing any harm to the environment. (c) Biomonitoring tools for toxicity analysis