Complete bio-degradation of poly(butylene adipate-co-terephthalate) via engineered cutinases

Abstract

Poly(butylene adipate-co-terephthalate) (PBAT), a polyester made of terephthalic acid (TPA), 1,4-butanediol, and adipic acid, is extensively utilized in plastic production and has accumulated globally as environmental waste. Biodegradation is an attractive strategy to manage PBAT, but an effective PBAT-degrading enzyme is required. Here, we demonstrate that cutinases are highly potent enzymes that can completely decompose PBAT films in 48 h. We further show that the engineered cutinases, by applying a double mutation strategy to render a more flexible substrate-binding pocket exhibit higher decomposition rates. Notably, these variants produce TPA as a major end-product, which is beneficial feature for the future recycling economy. The crystal structures of wild type and double mutation of a cutinase from Thermobifida fusca in complex with a substrate analogue are also solved, elucidating their substrate-binding modes. These structural and biochemical analyses enable us to propose the mechanism of cutinase-mediated PBAT degradation.

Tunable Thermal-Induced Degradation in Fully Bio-Based Copolyesters with Enhanced Mechanical and Water Barrier Properties

“…Nevertheless, the PBF decomposition rates of lipases or esterases are generally low, including CALB enzymes. The sluggish decomposition rates may be caused by narrow substrate-binding channels that prefer long fatty acids, not aromatic-containing polymers, as substrates. , …”

“…The sluggish decomposition rates may be caused by narrow substrate-binding channels that prefer long fatty acids, not aromatic-containing polymers, as substrates. 65,66 The above results prove the hydrolysis and enzymatic degradation resistance of PBFu crystals, providing longer usage and storage time.…”

Synergistic Modification of PBT with Diglycolic Acid and Succinic Acid: Fast Crystallization and High Strength-Toughness Copolyesters for Environmentally Degradable Packaging

“…Change of structural compositions detected by 1 H NMR was the most intuitive method to explore the degradation mechanism. 58 As summarized in Figure 6a−c and Table 3, the compositions of BS, BD, and BT segments are calculated according to eqs 2−4. PBS 50 T displayed a small decrease of n BS .…”

Biobased Biodegradable Copolyesters from 2,5-Thiophenedicarboxylic Acid: Effect of Aliphatic Diols on Barrier Properties and Degradation

“…2−10 Those that can undergo biodegradation through the hydrolytic scissions of ester bonds on their backbones, such as polylactide (PLA) and poly(butylene succinate) (PBS), have emerged as a class of new materials with fascinating properties. 2,6,7 Aromatic−aliphatic copolyesters have attracted particular attention due to their wide range of biodegradability and adjustable thermomechanical properties. 2 Undoubtedly, poly-(butylene adipate-co-terephthalate) (PBAT), under the brand name Ecoflex, is the most studied one.…”

“…2 Undoubtedly, poly-(butylene adipate-co-terephthalate) (PBAT), under the brand name Ecoflex, is the most studied one. 7 However, its mechanical properties and gas barrier performance are still unsatisfactory, and moreover, the key monomer terephthalic acid (PTA) is primarily produced from fossil resources. 2 Recently, copolyesters composed of FDCA were regarded as potential biobased substitutes to their PTA-based counterparts.…”