POLYMER
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2026
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IF 5.1
Linxi Xiao,Lin Chen,Xuehui Liu,Shimei Xu,Xiu-Li Wang,Yu-Zhong Wang
The extensive global utilization of polyethylene terephthalate (PET) has generated substantial post-consumer waste, leading to severe resource waste and environmental pollution that make efficient PET recycling an urgent scientific priority. Biological recycling of PET has gained widespread attention owing to mild reaction conditions, but current research predominantly targets the recovery of terephthalic acid, overlooking other key intermediates. This study focuses on the repolymerization of mono(2-hydroxyethyl) terephthalate (MHET), a distinctive intermediate derived from enzymatic depolymerization of PET, into high-quality PET. Under mild, catalyst-free conditions (180 °C, 6 h, atmospheric pressure), the process achieves a high esterification degree (>98%) while effectively suppressing the formation of diethylene glycol (DEG) as a by-product. Compared to PET's traditional polymerization routes, the route provided in this work demonstrates higher atom economy with an atomic utilization of 68.12%. And the resulting PET exhibits comparable properties to commercially available PET. By integrating experimental optimization, kinetic analysis, and environmental assessment, this work advances the practical optimization for the polymerization of PET from MHET, providing effective support for the closed-loop biological recycling of PET.
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DOI
高影响因子
BIORESOURCE TECHNOLOGY
·
2024
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IF 9.7
Kai Xue,Zhonghu Bai,Eric Fordour,Siqi Guo,Yuxuan Zhou,Yankun Yang,Xiuxia Liu,Ye Li,Chun-Li Liu
Biological degradation of PET plastic holds great potential for plastic recycling. However, the high costs associated with preparing free enzymes for degrading PET make it unfeasible for industrial applications. Hence, we developed various cell catalysts by surface-displaying PETase mutants and MHETase using autotransporters in E. coli and P. putida . The efficiency of surface display was enhanced through modifying the host, co-expressing molecular chaperones, and evoluting the autotransporter. In strain EC9F, PET degradation rate was boosted to 3.85 mM/d, 51-fold and 23-fold increase compared to free enzyme and initial strain ED1, respectively. The reusability of cell catalyst EC9F was demonstrated with over 38 % and 30 % of its initial activity retained after 22 cycles of BHET degradation and 3 cycles of PET degradation. The highest reported PET degradation rate of 4.95 mM/d was achieved by the dual-enzyme cascade catalytic system EC9F+EM2+R, a mixture of cell catalyst EC9F and EM2 with surfactant rhamnolipid.
研究领域:
生物化学
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环境微生物学
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合成生物学
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产品关联
DOI
PubMed
高影响因子
JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
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2024
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IF 5.7
Sizhong Feng,Mengke Xue,Fang Xie,Hongyang Zhao,Yemin Xue
The gene-encoding carboxylesterase (TM1022) from the hyperthermophilic bacterium Thermotoga maritima (T. maritima) was cloned and expressed in Escherichia coli Top10 and BL21 (DE3). Recombinant TM1022 showed the best activity at pH 8.0 and 85 °C and retained 57% activity after 8 h cultivation at 90 °C. TM1022 exhibited good stability at pH 6.0–9.0, maintaining 53% activity after incubation at pH 10.0 and 37 °C for 6 h. The esterase TM1022 exhibited the optimum thermo-alkali stability and kcat/Km (598.57 ± 19.97 s–1mM–1) for pN–C4. TM1022 hydrolyzed poly(ethylene terephthalate) (PET) degradation intermediates, such as bis(2-hydroxyethyl) terephthalate (BHET) and mono(2-hydroxyethyl) terephthalate (MHET). The Km, kcat, and kcat/Km values for BHET were 0.82 ± 0.01 mM, 2.20 ± 0.02 s–1, and 2.67 ± 0.02 mM–1 s–1, respectively; those for MHET were 2.43 ± 0.07 mM, 0.04 ± 0.001 s–1, and 0.02 ± 0.001 mM–1 s–1, respectively. When purified TM1022 was added to the cutinase BhrPETase, hydrolysis of PET from drinking water bottle tops produced pure terephthalic acids (TPA) with 166% higher yield than those obtained after 72 h of incubation with BhrPETase alone as control. The above findings demonstrate that the esterase TM1022 from T. maritima has substantial potential for depolymerizing PET into monomers for reuse.
研究领域:
生物化学
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环境科学
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微生物学
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DOI
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
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2022
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IF 14.224
Kun Chen,Xiaoyan Dong,Yan Sun
Accumulation of polyethylene terephthalate (PET) has brought an enormous threat to the ecosystem. The recently reported PET hydrolase (DuraPETase) and MHET hydrolase (MHETase) can synergistically catalyze the complete PET degradation. Hence, this work was designed to develop a bienzymatic cascade catalysis by co-immobilizing the two enzymes for PET biodegradation. DuraPETase and MHETase were sequentially co-immobilized in calcium phosphate nanocrystals (CaP) through SpyTag/SpyCatcher system. MHETase-SpyCatcher was first embedded inside the nanocrystals via biomimetic mineralization , and DuraPETase-SpyTag was then conjugated on the outlayer (~1.5 µm). The bienzyme compartmentalization facilitated DuraPETase interaction with the solid substrate, and the layered structures of the nanocrystals protected the enzymes, thus enhancing their stability. The high specific surface area of the nanocrystals and the proximity effects from the bienzymatic cascade were beneficial to the improved enzyme activity . Experimental data and molecular dynamics simulations revealed the activation effect of Ca 2+ on DuraPETase. Taken together, the final results indicate that the PET degradation efficiency of [email protected] increased by 6.1 and 1.5 times over the free bienzyme system within 10 d at 40 °C and 50 °C, with weight losses at 32.2% and 50.3%, respectively. The bienzymatic cascade with [email protected] can completely degrade PET, contributing to the recycling of PET.
研究领域:
生物技术
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环境科学
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纳米技术
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酶学
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DOI
PubMed
高影响因子
Synthetic and Systems Biotechnology
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2024
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IF 4.4
Haixia Wang,Jiahong Zhu,Meng Sun,Mengjie Gu,Xiya Xie,Tongtong Ying,Zeling Zhang,Weihong Zhong
The waste pollution problem caused by polyethylene terephthalate (PET) plastics poses a huge threat to the environment and human health. As plasticizers, Phthalate esters (PAEs) are widely used in PET production and become combined pollutants with PET. Synthetic biology make it possible to construct engineered cells for microbial degradation of combined pollutants of PET and PAEs. PET hydroxylase (PETase) and monohydroxyethyl terephthalate hydroxylase (MHETase) isolated from Ideonella sakaiensis 201-F6 exhibit the capability to depolymerize PET. However, PET cannot enter cells, thus enzymatic degradation or cell surface displaying technology of PET hydrolase are the potential strategies. In this study, Pseudomonas sp. JY-Q was selected as a chassis strain, which exhibits robust stress tolerance. First, a truncated endogenous outer membrane protein cOmpA and its variant Signal (OprF)-cOmpA were selected as anchor motifs for exogenous protein to display on the cell surface. These anchor motifs were fused at the N-terminal of PET hydrolase and MHETase and transformed into Pseudomonas sp. JY-Q, the mutant strains successfully display the enzymes on cell surface, after verification by green fluorescent protein labeling and indirect immunofluorescence assay. The resultant strains also showed the catalytic activity of co-displaying PETase and MHETase for PET biodegradation. Then, the cell surface displaying PET degradation module was introduced to a JY-Q strain which genome was integrated with PAEs degrading enzymes and exhibited PAEs degradation ability. The resultant strain JY-Q-R1-R4-SFM-TPH have the ability of degradation PET and PAEs simultaneously. This study provided a promising strain resource for PET and PAEs pollution control.
研究领域:
环境科学
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微生物学
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合成生物学
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生物技术
✓ 已验证
产品关联
DOI
PubMed
高影响因子
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