Polyols are one of the dominant reactants in polyurethane (PU) synthesis. However, polyols from Sapium sebiferum oil prepared by epoxidation–hydroxylation have an inferiority of secondary alcohol groups and large non-functional branches. Their lower reactivity, which in turn limits the properties of the generated PU. In this study, the optimal reaction conditions for the synthesis of polyols with primary alcohol groups by lipase hydrolysis have been investigated by single factorial experiments and response surface methodology. The optimized conditions for lipase hydrolysis were identified as a molar ratio of 2.2 : 1, a reaction time of 11.2 h, and a temperature of 47.2 °C. The highest hydroxyl value of the obtained polyol with primary alcohol groups reached 211 mg KOH per g. Furthermore, a novel PU was successfully synthesized from the synthetic polyol and isophorone diisocyanate by an in situ polymerization method. The generated PU showed a glass transition temperature of 60.6 °C, an initial decomposition temperature of 307.2 °C, a tensile strength of 12.5 MPa, and a Young's modulus of 22.3 MPa. These good thermal and mechanical properties of the PU prepared from the modified polyol by lipase hydrolysis can be attributed to its greater number of chemical interactions and cross-linked networks.

•For the fisrt time note AlgR directly binds rsmZ to regulate lipA expression mainly at transcriptional level in P. protegens Pf-5.Pseudomonas lipases are well studied enzymes. However, few studies have been conducted to explore the mechanism underlying the regulation of lipases expression. AlgR, a global regulator, controls the expression of multiple genes, regulates bacterial peristalsis, and participates in the regulation of quorum-sensing (QS) system, and so on. In this study, the effect of AlgR on lipase expression was investigated by knocking out the algR and rsmZ genes or overexpressing them. It is found out that AlgR can regulate the expression of lipA at both transcriptional and translational levels, but the transcriptional level was dominant. AlgR is also able to regulate the expression of rsmX/rsmY/rsmZ. Additionally, using algR/rsmZ double gene knock-out, it showed that AlgR could directly bind to the promoter sequence of rsmZ to regulate lipA activity. In conclusion, this study for the first time indicates that AlgR directly binds to rsmZ to regulates the expression of lipA via regulating transcription of rsmZ, and mainly regulates the expression of lipA at transcriptional level in P. protegens Pf-5.

Microcystins (MCs) produced by cyanobacteria have been recognized as a major public health threat. However, the toxicity of MCs to humans is still largely unknown. In this study, we examined the changes in pancreatic islet function in fishers exposed to ambient levels of MCs at Lake Taihu and, using a mouse model, explored the molecular mechanisms involved in toxicity. MCs content in the serum of fishers tested positive, with a range from 0.10 to 0.64 μg/L. Both lower blood insulin levels (2.26 ± 0.96 μIU/mL) and impaired fasting glucose were found in participants from the Meiliang Bay area in Lake Taihu, where MC-LR levels were substantially greater than the MC threshold established by WHO for drinking water. Animal experiments showed that glucose level increased by 27.9% in mice exposed to 5 μg/kg bw and decreased by 41.5% in mice exposed to 20 μg/kg bw. Blood insulin levels declined by 21.9% and 56.2% in mice exposed to 5 and 20 μg/kg bw MC-LR, respectively, which was consistent with the results observed in fishers. Furthermore, the diabetes gene pdx1 and several other proteins (such as Ppp3ca, Ide, Marcks, Pgk1, Suclg1, Ndufs4) involved in insulin secretion were identified for the first time in mice following MC-LR exposure; these biomarkers were considered responsible for MC-LR induced islet dysfunction. This study suggests that subchronic exposure to environmental levels of MCs may increase the risk of the occurrence of diabetes in humans.

A new hybrid nanoflower was synthesized using the organic component of Burkholderia cepacia lipase and inorganic component of calcium phosphate. Under the optimum conditions, the nanobiocatalyst exhibited an activity of 849.8 U, 308% folds of the free one, with relatively good stability, highlighting its potential for industrialization.

•The relationship of N content and magnetism of APTES modified m-MWCNTs was studied.•RML was oriented-immobilized based on the 3D structure analysis of molecule.•m-MWCNTs-PAMAM-lipase was easily recovered and recovery activity up to 2808%.•Biodiesel yield reached 94% and had no significant decrease after 10 cycles.A polyamidoamine (PAMAM) dendrimer was grafted onto magnetic multi-walled carbon nanotubes (m-MWCNTs) to combine magnetic properties with a large surface functionalized with amino groups. Based on three dimensional structural (3D) analysis of enzyme, oriented-immobilization of Rhizomucor miehei lipase (RML) on the obtained m-MWCNTs-PAMAM matrix was achieved. The recovery activity of the immobilized lipase was up to 2808% and the corresponding esterification activity was 27-fold higher than that of the free enzyme. The immobilized enzyme was employed to catalyze biodiesel production from waste vegetable oil in a tert-butanol solvent system. Biodiesel conversion reached 94% under optimal conditions. Moreover, the immobilized lipase could be easily recovered and there was no significant decrease in conversion rates after 10 cycles of reuse. The results suggested that the immobilized RML is a potential catalyst with high stability and excellent operational reusability for biodiesel production.

With the development of civil engineering, the demand for suitable cementation materials is increasing rapidly. However, traditional cementation methods are not eco-friendly enough and more sustainable approach such as biobased cementation is required. To meet such demand, Euk.cement, a living eukaryotic cell-based biological autocementation kit, was created in this work. Through the surface display of different silica binding peptides on the fungus Yarrowia lipolytica, Euk.cement cells can immobilize onto any particles with a silica containing surface with variable binding intensity. Meanwhile, recombinant MCFP3 released from the cells will slowly consolidate this binding of cells to particles. The metabolism of immobilized living cells will finally complete the carbonate sedimentation and tightly stick the particles together. The system is designed to be initiated by blue light, making it controllable. This autocementation kit can be utilized for industrial and environmental applications that fit our concerns on making the cementation process eco-friendly.Keywords: autocementation; silica binding peptides; surface display; Yarrowia lipolytica;

Genetic modifications are considered as one of the most important technologies for improving fermentative hydrogen yield. Herein, we overexpress fhlA and pncB genes from Klebsiella HQ-3 independently to enhance hydrogen molar yield. HQ-3-fhlA/pncB strain is developed by manipulation of pET28-Pkan/fhlA Kanr and pBBR1-MCS5/pncB Gmr as expression vectors to examine the synchronous effects of fhlA and pncB. Optimization of anaerobic batch fermentations is achieved and the maximum yield of biohydrogen (1.42 mol H2/mol of glucose) is produced in the range of pH 6.5–7.0 at 33–37 °C. Whole cell H2 yield is increased up to 40 % from HQ-3-fhlA/pncB, as compared with HQ-3-fhlA 20 % and HQ-3-pncB 12 % keeping HQ-3-C as a control. Mechanism of improved H2 yield is studied in combination with metabolic flux analysis by measuring glucose consumption and other metabolites including formate, succinate, 2,3 butanediol, lactate, acetate, ethanol, and hydrogen. The results suggest that under transient conditions, the increase in the total level of NAD by NAPRTase can enhance the rate of NADH-dependent pathways, and therefore, final distribution of metabolites is changed. Combined overexpression of fhlA and pncB eventually modifies the energy and carbon balance leading to enhanced H2 production from FHL as well as by NADH pathway.

•ROL-catalyzed biodiesel production was enhanced by a synergic effect.•Non-regioselective lipases were systematically screened.•Enzymatic reaction time was shortened from 60 h to 21 h.•Approximately 80% of the biodiesel yield was retained after 20 cycles.Industrialization of enzyme-catalyzed biodiesel production has been hindered by low conversion efficiency and long reaction time. As a representative example, Rhizopus oryzae lipase (ROL) exhibited a poor performance in biodiesel production. However, higher yields and shorter reaction time could be achieved by screening different lipases that could synergically catalyze the reaction with ROL. The results showed that Novozym 435 combined with ROL displayed the best performance, with a biodiesel yield that was 30% higher than that of ROL alone in 30 h. Hence, the use of a synergic strategy was investigated systematically. Under optimized conditions, the biodiesel yield was as high as 98.3% and the reaction time was successfully shortened from 60 h to 21 h. Moreover, the combined lipases retained a yield of about 80% after 20 cycles in a solvent-free system. In addition to ROL, the performance of other lipases whose regioselectivity were similar to ROL was improved when they were combined with Novozym 435. In conclusion, synergic catalysis is a promising strategy for enhancing biodiesel yield and minimizing reaction time for ROL.

The physicochemical properties and fatty acid profile of natural Sapium sebiferum oil (SSO) were analyzed and found to have a high iodine value of 186.8 g/100 g. Then, a novel SSO-based polyurethane (PU) was successfully synthesized via an in situ polymerization method, and multi-walled carbon nanotubes (CNTs) were modified by an acid mixture and ethylenediamine (EDA) to further reinforce the PU matrix. The microstructure and the properties of the functionalized CNTs and the PU/CNT composites were characterized by Fourier transform infrared (FTIR), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The results showed that amino-functionalized CNTs could homogeneously disperse in the PU matrix and significantly improved the thermal and mechanical properties of the composite. Compared with pure PU, the glass transition temperature and initial decomposition temperature of the PU matrix with amino-functionalized CNTs were respectively enhanced by 17.1 and 32.5 °C. Meanwhile, 295% improvement in the tensile strength, 111.3% enhancement in the Young's modulus and 22.4% increment in the elongation at break of the composite were observed. The properties of the PU/CNT composites indicate the great potential applications of SSO in polymer materials.

Novel Sapium sebiferum oil-based polyurethane (PU) nanocomposites with different contents of nano-SiO2 were successfully synthesized via an in situ polymerization method. Firstly, Sapium sebiferum polyol (SSP) was prepared in a continuous two-step process of epoxidation and hydroxylation, and nano-SiO2 particles were modified with 3-aminopropyltriethoxysilane (AMEO). Furthermore, SSP and isophorone diisocyanate (IPDI) reacted with a certain amount of the modified nano-SiO2 to enhance the physical properties of PU nanocomposites. The characterization of the structure and the properties of the surface modified nano-SiO2 and the PU/SiO2 nanocomposites were analyzed by Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), solid-state 29Si nuclear magnetic resonance (NMR), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The results demonstrate that nano-SiO2 particles can be homogeneously dispersed in the PU matrix with a loading amount less than 5 wt%. Compared with the pure PU, the glass transition temperatures and initial decomposition temperatures of the PU/SiO2 nanocomposites were respectively enhanced by 20.5 °C and 43.5 °C with 3 wt% nano-SiO2 content. Moreover, the tensile strength of the PU/SiO2 nanocomposites was improved at 170%, and the water and toluene resistance properties of PU/SiO2 were also significantly enhanced.

Biomass-based new materials have attracted wide attention due to their renewable characteristics. In this study, the synthesis of dimeric acid polyester polyol (DAPP) was conducted through the polymerization of dimeric acid methyl ester (DAME) and ethylene glycol (EG) using Novozym 435 as a catalyst. DAME was synthesized from Chinese tallow kernel oil biodiesel and purified via molecular distillation. To examine the effects of different parameters on the polymerization reaction, both single factorial experiments and response surface methodology (RSM) were employed. The optimized conditions were a Novozym 435 dosage of 2.9% (w/w), reaction temperature of 70 °C, molar ratio of EG–DAME of 2.2:1.0, and reaction time of 9.7 h. The highest hydroxyl value of the obtained DAPP was 87.47 mg KOH g−1. Its molecular weight and acid value were 1275 g mol−1 and 0.56 mg KOH g−1. The product was further confirmed by FTIR and NMR. Then, the synthesized DAPP was refined into polyurethane (PU) with isophorone diisocyanate (IPDI). The TGA analysis of the synthetic polyurethane showed good thermostability. At the initial heating stage, no volatile constituents escaped. With an increase in temperature, thermal decomposition was divided into two stages: the first stage at 240–370 °C and the second at 370–480 °C. When the temperature reached 480 °C, the polyurethane was completely decomposed without any residue. DSC analysis also indicated that polyurethane had good performance at lower temperatures, with a low glass transition temperature of −52 °C, and there was only one peak, suggesting that the polyurethane is suitable for use in the coating industry.

•NAD synthetase overexpression increased NAD(H) pool, reduced NADH/NAD+ ratio.•Low NADH/NAD+ ratio improved glucose uptake, enhanced hydrogen yield.•High level NAD(H) pool promoted hydrogen production.•Double modification strategy exhibited positive synergistic effect.•The mutant strain produced 2.89 mol H2/mol glucose and 5.1 L H2/L.The effects of combining two strategies, recycling NAD and improving the availability of NADH, on hydrogen production in Enterobacter aerogenes were investigated. The NAD synthetase encoded by nadE gene was homologously overexpressed in AB91002-O, which had been obtained previously, to increase the intracellular concentration of the NAD(H/+) pool. This overexpression was duplicated in mutant strains in which the phosphoenolpyruvate carboxylase (PEPC) gene (ppc) and hybO gene were knocked out, yielding AB91102-OP (ΔhybO/Δppc), AB91102-ON (ΔhybO/nadE), and AB91102-OP/N (ΔhybO/Δppc/nadE). Chemostat experiments showed that the total NAD(H) pool size in AB91102-ON increased 2-fold compared with the control strain AB91102-OC, but the NADH/NAD+ ratio decreased by 24%. Metabolic analysis of batch experiments indicated that a larger NAD(H/+) pool and inactivation of PEPC led to a significant shift in metabolic patterns, whereas a smaller NADH/NAD+ ratio improved glucose uptake. Thus, compared with the control strain, the hydrogen yields per glucose of the mutant strains AB91102-OP, AB91102-ON, and AB91102-OP/N were enhanced by 36.2%, 66.0%, and 149%, respectively, and the total volumes of hydrogen production increased by 27%, 165%, and 301%, respectively. The maximum hydrogen production of 5.1 L/L was achieved by AB91102-OP/N, suggesting that the double modification strategy exhibits markedly positive synergistic effects on hydrogen production.

Enzymatic biodiesel production was investigated in solvent-free and isooctane systems using Burkholderia cenocepacia lipase (BCL) immobilized on macroporous resin NKA as a biocatalyst. A total of 98% biodiesel yield was obtained under the optimized conditions of methanol/oil molar ratio 4:1 with the addition of methanol in three steps at intervals of 2 h, enzyme dosage 2.5 wt % (based on the oil weight), moisture concentration 7 wt % (based on oil weight), reaction temperature 40 °C, reaction duration 8 h, stirring rate 300 rpm, and isooctane amount 50 wt % (based on the oil weight). Compared to tert-butanol and solvent-free systems, the highest biodiesel yield was achieved in the isooctane system. BCL−NKA showed high operational stability with no obvious loss in lipase activity for transesterification in the isooctane system even after 50 cycles (400 h) of repeated usage. It has been revealed that BCL−NKA-catalyzed transesterification in the isooctane system is a promising alternative for biodiesel production.

•Metal ions chelated magnetic nanoparticles were successfully synthesized.•β-Glucosidase was successfully immobilized on magnetic nanoparticles.•The immobilized β-glucosidase showed enhanced activity and good reusability.•The immobilized β-glucosidase was promising in application.A novel magnetic Fe3O4 nanoparticles (MNPs) coupled with agarose (AMNPs) was synthesized using co-precipitation via alkaline condition and span-80 surfactants in organic solvent. Iminodiacetate was first attached to the MNPs through epichlorohydrin agent and then chelated with metal ions. The morphology and chemical properties of these prepared supports were characterized by scanning electron microscopy (SEM), X-ray power diffraction (XRD), vibrating sample magnetometer (VSM), and Fourier transform infrared spectroscopy (FT-IR). Among them, the Co2+-chelated AMNPs (AMNPs-ECH-IDA-Co2+) showed the second highest enzyme adsorption capacity of 1.81 mg/g particles, and achieved the largest activity recovery of 117% per protein gram in immobilization of β-glucosidase (BGL). The Michaelis constant (Km) and Vmax of the immobilized BGL were 0.904 mM and 0.057 μmol/min, respectively, and its activation energy was much lower than the free form. Moreover, the immobilized enzyme exhibited enhanced thermostability and operational stability. It still retained more than 90% of its initial activity after being operated for 15 successive batches. This study demonstrates that the immobilized β-glucosidase has a good prospect in industrial applications.

•Genes encoding hydrogenase-3 were successfully knocked out.•Gene knockout inhibits FHL hydrogen production pathway.•Gene knockout synchronously inhibits NADH pathway.•NADH pathway proven definitely involving hydrogenase-3.In this study, the hydrogenase-3 gene cluster (hycDEFGH) was isolated and identified from Enterobacter aerogenes CCTCC AB91102. All gene products were highly homologous to the reported bacterial hydrogenase-3 (Hyd-3) proteins. The genes hycE, hycF, hycG encoding the subunits of hydrogenase-3 were targeted for genetic knockout to inhibit the FHL hydrogen production pathway via the Red recombination system, generating three mutant strains AB91102-E (ΔhycE), AB91102-F (ΔhycF) and AB91102-G (ΔhycG). Deletion of the three genes affected the integrity of hydrogenase-3. The hydrogen production experiments with the mutant strains showed that no hydrogen was detected compared with the wild type (0.886 mol/mol glucose), demonstrating that knocking out any of the three genes could inhibit NADH hydrogen production pathway. Meanwhile, the metabolites of the mutant strains were significantly changed in comparison with the wild type, indicating corresponding changes in metabolic flux by mutation. Additionally, the activity of NADH-mediated hydrogenase was found to be nil in the mutant strains. The chemostat experiments showed that the NADH/NAD+ ratio of the mutant strains increased nearly 1.4-fold compared with the wild type. The NADH-mediated hydrogenase activity and NADH/NAD+ ratio analysis both suggested that NADH pathway required the involvement of the electron transport chain of hydrogenase-3.

•MC-LR exposure alters ER morphology and insulin content in β-cells.•Genes related to ER stress-mediated apoptosis were identified after MC exposure.•PERK-eIF2α-ATF4 pathway are involved in β-cell dysfunction induced by MC-LR.Microcystins (MCs) widely distributed in freshwaters have posed a significant risk to human health. Previous studies have demonstrated that exposure to MC-LR impairs pancreatic islet function, however, the underlying mechanisms still remain unclear. In the present study, we explored the role of endoplasmic reticulum (ER) impairment in β-cell dysfunction caused by MC-LR. The result showed that MC-LR modified ER morphology evidenced by increased ER amount and size at low doses (15, 30 or 60 μM) and vacuolar and dilated ER ultrastructure at high doses (100 or 200 μM). Also, insulin content showed increased at 15 or 30 μM but declined at 60, 100, or 200 μM, which was highly accordant with ER morphological alteration. Transcriptomic analysis identified a number of factors and several pathways associated with ER protein processing, ER stress, apoptosis, and diabetes mellitus in the cells treated with MC-LR compared with non-treated cells. Furthermore, MC-LR-induced ER stress significantly promoted the expression of PERK/eIF2α and their downstream targets (ATF4, CHOP, and Gadd34), which indicates that PERK-eIF2α-ATF4 pathway is involved in MC-LR-induced insulin deficiency. These results suggest that ER impairment is an important contributor to MC-LR-caused β-cell failure and provide a new insight into the association between MCs contamination and the occurrence of human diseases.Download high-res image (185KB)Download full-size image

•A new lipase SL-4 of Burkholderia ubonensis SL-4 was more stable at 50 °C and pH 8.5.•Lipase SL-4 was activated by Ca2+ or Mn2+, but inhibited by EDTA, PMSF, DTT and β-ME.•Lipase SL-4 had non-ionic detergent- and organic solvent-stability.•Liquid lipase SL-4 could catalyze soybean oil to biodiesel at a yield rate of 92.24%.In the present study, a new lipase SL-4 from Burkholderia ubonensis SL-4, was purified by 80% ammonium sulphate precipitation, Q Sepharose FF anion exchange and Superdex 75 gel filtration chromatography finally leading to 68.5-fold purification and 13.34% recovery. It had a molecular mass of ca. 33 kDa and the whole gene (1095-bp) was cloned by using degenerate primers. Amino acid sequence analysis revealed that lipase SL-4 is a new member of subfamily I.2 lipases. Lipase SL-4 exhibited optimum activity toward p-NP myristate (C14) at pH 8.5 and 65 °C with a Km of 0.72 mM, a kcat of 391.63 s−1 and a kcat/Km of 543.93 s−1 mM−1. It had good thermostability at 50 °C and pH 8.5, and could be activated strongly by Ca2+ and Mn2+, but inhibited by some transition metal ions and EDTA, PMSF, DTT and β-ME. Additionally, lipase SL-4 possessed non-ionic detergent stability and organic solvent stability. When preliminarily employed to catalyze soybean oil for biodiesel production, the liquid lipase SL-4 could attain a conversion ratio of 92.24% in a solvent-free system. These results demonstrate that the new thermo-solvent-stable lipase possesses an attractive potential for biotechnological applications as biocatalyst, especially for biodiesel production.Download full-size image

•The CO-difference spectra of HmtT and HmtN show absorbance at 450 nm.•Instead of lying at the entrance of the active site, the exceptionally long F–G loop of HmtT takes a highly unusual conformation and extends deep into the active site. As a result, both F and G helices of HmtT are kinked.•The F/G helices adopt distinctive orientations in HmtT and HmtN, which may play a role in distinguishing subtle differences on the highly homologous substrates.Himastatin is a novel antibiotic featuring a bicyclohexadepsipeptide structure. On the himastatin biosynthesis pathway, three cytochrome P450s (HmtT, HmtN, HmtS) are responsible for the post-tailoring of the cyclohexadepsipeptide backbone. Here we report the crystal structures of HmtT and HmtN. The overall structures of these two proteins are homologous to other cytochrome P450s. However, the exceptionally long F–G loop in HmtT has a highly unusual conformation and extends deep into the active site. As a result, the F/G helices of HmtT are both kinked. In contrast, the F/G helices of HmtN are straight. Also, the F/G helices in HmtT and HmtN take distinctive orientations, which may be a contributing factor for the substrate specificity of these two enzymes.

•Mice exposed to MC-LR showed metabolic disorders with physiological aberrations.•Those metabolic disorders after MC-LR exposure are associated with thyroid dysfunction.•Molecular levels involved in metabolic disorders were significantly changed.There is growing evidence that microcystins (MCs) act as hazardous materials and can disrupt the endocrine systems of animals. However, the response of thyroid function and the related energy metabolism following MCs exposure is still unknown. In the present study, mice were injected intraperitoneally (i.p.) with doses of either 5 or 20 μg/kg MC-LR for 4 weeks. We report, for the first time, that mice exposed to 20 μg/kg MC-LR showed disrupted glucose, triglyceride and cholesterol metabolism with obvious symptoms of hyperphagia, polydipsia, and weight loss. The circulating thyroid hormone (TH) levels in mice following MC-LR exposure were detected. Significantly increased free triiodothyronine (FT3) and decreased free thyroxin (FT4) were largely responsible for the physiological aberrations and metabolic disorders observed in mice after the 20 μg/kg MC-LR exposure. Increased expression of TH receptor (Trα) and mTOR expression in the brain after the 20 μg/kg MC-LR exposure suggests that the increased FT3 enhanced mTOR signaling subsequently led to hyperphagia and elevated energy expenditure in mice. Furthermore, several genes involved in glucose homeostasis and lipid metabolism, which have been identified affected by TH, were also differentially expressed after MC-LR exposure. The above results clearly showed that mice exposed to MC-LR experienced thyroid dysfunction and its downstream functional changes, and are useful to better understand the endocrine toxicity of MC-LR to mammals or even humans.

•Most compressed CO2 treatments significantly enhanced PCL esterification activity.•High pressure treatment facilitated PCL's esterification reactions.•The secondary and tertiary structure changes were responsible for activity variations.•The stability of PCL significantly decreased in esterification after supercritical treatment.In this work, we have investigated the influences of sub- and supercritical CO2 treatment on the properties of Pseudomonas cepacia lipase (PCL), including its esterification and transesterification activities, structural changes and stability. Results demonstrated that exposure time to subcritical CO2 treatment had a negative effect on PCL transesterification activity whereas exposure time to supercritical CO2 treatment had a positive effect. But generally, most compressed treatments significantly enhanced PCL esterification activity. Conformational analysis by FT-IR and fluorescence emission spectra revealed that enhanced activities after supercritical CO2 treatment were correlated with the secondary and tertiary structural changes of PCL. Secondary structure changes also appeared to be responsible for enhancement of PCL activities by subcritical CO2 treatment. Compared to native PCL, treated PCL's esterification activity significantly decreased in hydrophilic organic media, while transesterification activity significantly increased in tert-amyl alcohol and acetone. After supercritical treatment, the thermal stability of PCL significantly decreased in esterification reactions, however, there was no significant difference in transesterification reactions.