Enzymes for the Biofunctionalization of Poly(Ethylene Terephthalate)

Abstract

The functionalization of synthetic polymers such as poly(ethylene terephthalate) to improve their hydrophilicity can be achieved biocatalytically using hydrolytic enzymes. A number of cutinases, lipases, and esterases active on polyethylene terephthalate have been identified and characterized. Enzymes from Fusarium solani, Thermomyces insolens, T. lanuginosus, Aspergillus oryzae, Pseudomonas mendocina, and Thermobifida fusca have been studied in detail. Thermostable biocatalysts hydrolyzing poly(ethylene terephthalate) are promising candidates for the further optimization of suitable biofunctionalization processes for textile finishing, technical, and biomedical applications.

A Practical Fluorescence-Based Screening Protocol for Polyethylene Terephthalate Degrading Microorganisms

“…11,23 This higher hydrolysis rate provided by the enhanced surface area can overcome the limitation caused by the densely packed structure of PET bottles, resulting in greater enzyme access to PET polyester chains. 4 The fungus Aspergillus oryzae C361 showed one of the highest conversions of PET nanoparticles (Table 1). Similar potential of the this fungus to hydrolyze PET was also investigated by Wang et al, 24 by applying an extracellular lipase to promote a modification (hydrolysis) in the PET fabric.…”

“…C70 strain assay (second generation grown in PET-enriched medium) was analyzed by MALDI-TOF MS after 15 days and showed the presence of the intermediate MHET (4), highlighted by both m/z peak 210.905 and the sodium adduct [M + Na] + in m/z 233.030, evident in the mass spectra (Figure 3). TPA (2) was also detected in m/z peak 166.920 in the mass spectra, while m/z peak 402.332 can be referred to as the hydrolysis product 1,2-ethylene-mono-terephthalate-mono(2-hydroxyethyl) terephthalate (EMT, 5).…”

“…2,3 Polyethylene terephthalate (PET) is an aromatic polyester widely used to make beverage bottles, films and textile fibers, owing to its excellent mechanical strength, high chemical resistance and low gas permeability. 4 These properties, along with its competitive price, have made PET the most widely produced polyester and the most commonly used synthetic fiber, with 56 million metric tons produced in 2013. Increased production and disposal of PET has led to large amounts of the polymer and its oligomers in the environment, composed primarily of terephthalic acid (TPA) and ethylene glycol (EG) monomers.…”

“…7 Hydrolytic activity against PET has been identified in filamentous fungi, such as Fusarium oxysporum and Fusarium solani, 8 and in bacteria from the genus Thermobifida, 9 with enzymes such as cutinases (EC 3.1.1.74), lipases (EC 3.1.1.3), and carboxylesterases (EC 3.1.1.1) involved in PET degradation. 4 This is usually monitored by high-performance liquid chromatography (HPLC), which separates monomeric TPA from its ethylene glycol esters, namely mono(2-hydroxyethyl) terephthalate (MHET) and bis-(2-hydroxyethyl) terephthalate (BHET), among other hydrolysis products. Additionally, a number of approaches to evaluate the extent of biodegradation have been used, including turbidimetric analysis, 10 titration, 11 image scanning, 12 and polymer film weight loss monitoring.…”

Expression and characterization of a cutinase (AnCUT2) from Aspergillus niger

“…Synthetic polyesters (PET), most commonly used polymer in beverage containers, food packaging and electronic industry [42], represents a total of 50% of the global market for textile fibers [43]. An increased hydrophilicity of the fiber is required to facilitate the dyeing process of these fibers using enzymatic treatments as opposed to using harsh chemicals.…”