Monomethyl Terephthalate Research Articles

PARP1 promotes tumor proliferation in lenalidomide-resistant multiple myeloma via the downregulation of microRNA-192-5p-AKT signaling.

Lenalidomide-based therapies are recommended as first-line treatment for multiple myeloma (MM) patients, regardless of the transplant eligibility. Resistance to lenalidomide is a clinical problem that urgently needs to be addressed. The expression of poly(ADP-ribose) polymerase 1 (PARP1) is abnormally high in a variety of tumor tissues including MM. However, in lenalidomide-resistant MM, it is not yet known whether the abnormally high expression of PARP1 is involved in the occurrence of drug resistance, and whether the inhibition of PARP1 can reverse lenalidomide resistance. The aim of this study was to investigate the mechanism of PARP1 promoting lenalidomide-resistant in MM patients. Samples of bone marrow from patients with MM who were sensitive or resistant to lenalidomide were collected. The expression levels of PARP1 at the messenger RNA and protein levels were detected through polymerase chain reaction and western blot. MM cell lines were cultivated in vitro, cell lines resistant to lenalidomide were screened out, and the expression levels of PARP1 in the resistant cell lines were detected. The apoptosis level was also detected in the lenalidomide-resistant MM cell lines treated with a PARP1 inhibitor. The proliferation rates of the two groups of cells at different time points were evaluated by mono-methyl terephthalate (MMT) experiments. Finally, the effect of PARP1 on the proliferation of lenalidomide-resistant MM through the microRNA-192-5p-AKT signaling pathway was analyzed. In the lenalidomide-resistant cell lines, the expression level of PARP1 was higher, the proliferation more rapid, and the apoptosis rate was lower than lenalidomide-sensitive cell lines. Additionally, the activated AKT pathway was suppressed by downregulating the expression of microRNA-192-5p. MM resistance can be inhibited to some extent by impacting PARP1. PARP1 is involved in the production of lenalidomide resistance in MM, and could serve as a potential target for the treatment of MM in the future.

Kinetic modelling and mechanism elucidation of catalyst-free dimethyl terephthalate hydrolysis process intensification by reactive distillation

Polyethylene terephthalate (PET) is a widely used thermoplastic polymer in the packaging and materials industries, and is predicted to have continuous market growth in the future. Methods such as glycolysis and methanolysis of PET have been identified as promising approaches in sustainable chemical recycling of PET. The latter produces dimethyl terephthalate (DMT), which can be easily hydrolyzed to terephthalic acid (TPA) at elevated temperatures and pressures, and further reused for PET production. The aim of this study was to develop a kinetic model for the hydrolysis of dimethyl terephthalate, using the experimental data. Various reaction conditions (temperature, pressure, time) have been investigated and used to calculate the activation energies and reaction rate constants, while the variation in reactor setup with methanol (MeOH) removal was conducted to show its detrimental effect on the efficiency of the reaction and selectivity towards terephthalic acid. The first reaction step of DMT to monomethyl terephthalate (MMT) is relatively irreversible, while the second reaction step of MMT to TPA ceases, as soon as the equilibrium is reached. Highest yields of TPA (76.7 %) were obtained after 40 min at 265 °C, with MeOH removal, and the activation energy was calculated to be 95 and 64 kJ mol−1 for the first and second hydrolysis reaction step, respectively.

Biodegradation of polyethylene terephthalate (PET) by Brucella intermedia IITR130 and its proposed metabolic pathway.

Accumulation of polyethylene terephthalate (PET) polyester in ecosystems across the globe is a major pollution of concern. Microbial degradation recently generated novel insights into the biodegradation of varieties of plastics. In this study, a PET degrading bacterium Brucella intermedia IITR130 was isolated from a contaminated lake ecosystem at Pallikaranai, Chennai, India. Incubation of the bacterium along with the PET sheet (0.1mm thickness) for 60 days resulted in 26.06% degradation, indicating a half-life of 137.8 days. Considerable changes in the surface morphology of the PET sheet were found as holes, pits, and cracks on incubation with strain IITR130, as revealed by scanning electron microscopy (SEM). After bacterial treatment of PET, the formation of new functional groups, most notably in the area of 3326cm-1 suggestive of O-H stretch, leading to carboxylic acid and alcohol as products were suggested by fourier transform infrared (FTIR) analysis. Monomethyl terephthalate (MMT) and terephthalic acid (TPA) were identified by gas chromatography-mass spectrometry (GC-MS) analysis as PET degradation metabolites. Tributyrin clearance assay confirmed the presence of a lipase/esterase enzyme in the strain IITR130. In this study, a degradation pathway for PET by an isolated and identified bacterium Brucella intermedia IITR130 was characterized in detail.

Characterization of non-volatile organic contaminants in coking wastewater using non-target screening: Dominance of nitrogen, sulfur, and oxygen-containing compounds in biological effluents

While abundant volatile compounds (VOCs) have been identified in coking wastewater, the structures and occurrence of non-volatile organic compounds (non-VOCs) have remained unknown. In this study, 3966 non-VOCs belonging to 24 groups were tentatively identified for the first time in wastewater from four biological coking wastewater treatment systems in northern China using a non-target screening technique. A total of 227 compounds with CHNO, CHO, CHOS, and CHNOS elemental compositions were assigned with level 2 identification confidence, and 19 of them were confirmed with authentic standards, with 9-methyl-9H-carbazole-3-carbaldehyde (1706.3–2032.7 μg/L) and 3-Indolyl acetic acid monomethyl terephthalate (773.7–1449.9 μg/L) as the top two compounds in the influents, and 9-methyl-9H-carbazole-3-carbaldehyde (31.8–130.1 μg/L) and monomethyl terephthalate (13.9–196.6 μg/L) as the top two in the effluents. The four groups of substances accounted for 93.4% and 71.5% of the total responses of tentatively identified compounds in the influents and biological effluents, respectively, and were estimated to contribute 32.3–48.9% of the chemical oxygen demand in the biological effluents. In comparison with those in the influent, abundant S-containing compounds (CHOS and CHNOS, 35.2% of the total responses) were observed in the biological effluents, suggesting their highly bio-refractory characteristics. The advanced treatment process using synchronized oxidation-adsorption could almost completely remove the CHOS and CHNOS compounds from the biological effluents.

Catalytic Degradation of Polyethylene Terephthalate Using a Phase‐Transitional Zirconium‐Based Metal–Organic Framework

AbstractPolyethylene terephthalate (PET) is utilized as one of the most popular consumer plastics worldwide, but difficulties associated with recycling PET have generated a severe environmental crisis with most PET ending its lifecycle in landfills. We report that zirconium‐based metal–organic framework (Zr‐MOF) UiO‐66 deconstructs waste PET into the building blocks terephthalic acid (TA) and mono‐methyl terephthalate (MMT) within 24 hours at 260 °C (total yield of 98 % under 1 atm H2 and 81 % under 1 atm Ar). Extensive structural characterization studies reveal that during the degradation process, UiO‐66 undergoes an intriguing transformation into MIL‐140A, which is another Zr‐MOF that shows good catalytic activity toward PET degradation under similar reaction conditions. These results illustrate the diversity of applications for Zr‐MOFs and establish MOFs as a new class of polymer degradation catalysts with the potential to address long‐standing challenges associated with plastic waste.

Catalytic Degradation of Polyethylene Terephthalate Using a Phase-Transitional Zirconium-Based Metal-Organic Framework.

Polyethylene terephthalate (PET) is utilized as one of the most popular consumer plastics worldwide, but difficulties associated with recycling PET have generated a severe environmental crisis with most PET ending its lifecycle in landfills. We report that zirconium-based metal-organic framework (Zr-MOF) UiO-66 deconstructs waste PET into the building blocks terephthalic acid (TA) and mono-methyl terephthalate (MMT) within 24 hours at 260 °C (total yield of 98 % under 1 atm H2 and 81 % under 1 atm Ar). Extensive structural characterization studies reveal that during the degradation process, UiO-66 undergoes an intriguing transformation into MIL-140A, which is another Zr-MOF that shows good catalytic activity toward PET degradation under similar reaction conditions. These results illustrate the diversity of applications for Zr-MOFs and establish MOFs as a new class of polymer degradation catalysts with the potential to address long-standing challenges associated with plastic waste.

Potential of esterase DmtH in transforming plastic additive dimethyl terephthalate to less toxic mono-methyl terephthalate

Dimethyl terephthalate (DMT) is a primary ingredient widely used in the manufacture of polyesters and industrial plastics; its environmental fate is of concern due to its global use. Microorganisms play key roles in the dissipation of DMT from the environment; however, the enzymes responsible for the initial transformation of DMT and the possible altered toxicity due to this biotransformation have not been extensively studied. To reduce DMT toxicity, we identified the esterase gene dmtH involved in the initial transformation of DMT from the AOPP herbicide-transforming strain Sphingobium sp. C3. DmtH shows 24–41% identity with α/β-hydrolases and belongs to subfamily V of bacterial esterases. The purified recombinant DmtH was capable of transforming DMT to mono-methyl terephthalate (MMT) and potentially transforming other p-phthalic acid esters, including diallyl terephthalate (DAT) and diethyl terephthalate (DET). Using C. elegans as an assay model, we observed the severe toxicity of DMT in inducing reactive oxygen species (ROS) production, decreasing locomotion behavior, reducing lifespan, altering molecular basis for oxidative stress, and inducing mitochondrial stress. In contrast, exposure to MMT did not cause obvious toxicity, induce oxidative stress, and activate mitochondrial stress in nematodes. Our study highlights the usefulness of Sphingobium sp. C3 and its esterase DmtH in transforming p-phthalic acid esters and reducing the toxicity of DMT to organisms.

Enhanced electroluminescent performance by doping organic conjugated ionic compound into graphene oxide hole-injecting layer

Organic conjugated ionic compound 10,10′-dimethyl-9,9′-biacridinum bis(monomethyl terephthalate) (MMT) is doped into graphene oxide (GO) hole-injecting layer to enhance the electroluminescent performance of organic light-emitting diodes (OLEDs). The composite films are characterized in detail by FTIR, SEM, XPS, and UPS. The XPS result indicates the evident π–π stacking interaction between the conjugated structures of GO and MMT. The UPS result shows the decrease in ionization potential of GO due to MMT-doping. As a result, at the optimal doping ratio of 4 wt%, the maximum luminous efficiency of OLEDs is increased to 15.46 cd/A, which is 3.4 times as 4.55 cd/A of the control device. Besides, the luminance is also enhanced to 19950 cd/m2, while the turn-on voltage is decreased to 2.5 V. Doping organic conjugated ionic compound into the GO hole-injecting layer is a facile and efficient approach to improve the electroluminescent performance of OLEDs.

Optimization of the post-acquisition data processing for the non-targeted screening of trace leachable residues from reusable plastic bottles by high performance liquid chromatography coupled to hybrid quadrupole time of flight mass spectrometry

Food safety regulations for food contact materials (FCM) usually rely on the assessment of chemical migration in order to reduce human exposure to chemical residues that could leach from the FCM into the food. In this field, there is a need for non-targeted analytical tools which can identify unknown or unexpected leachable residues, and therefore avoid unwanted human exposure. In this study, a method based on high performance liquid chromatography coupled to hybrid quadrupole time of flight mass spectrometry (HPLC-QTOF-MS) was developed and optimized to investigate leachable residues from 30 reusable plastic bottles. Firstly, a method was validated for the targeted analysis of the 11 bisphenol analogues. None of the bisphenols were detected in the food simulants (ethanol/water; 50:50 v/v), indicating that all tested bottles are free of BPA, and that bisphenol analogues were not applied as BPA replacement in bottle manufacture. The effect of post-acquisition data processing parameters on the feature extraction in non-targeted analysis was then systematically investigated. Several parameters significantly reduced the number of correct identifications of some target trace residues, which confirms that data post-processing has to be carefully optimized to decrease the risk of false negatives. The optimized method was effectively applied to the 30 bottle samples, and monomethyl terephthalate was identified at trace level in food simulants in contact with Tritan™ bottles (migration rate of 0.054 ± 0.002–0.53 ± 0.021 µg cm−2 per 10 days at 40 °C). This method can therefore be applied to study the leachable residues from other FCMs and offer some novel information for human risk assessments.

Sodium Methoxide Catalyzed Depolymerization of Waste Polyethylene Terephthalate Under Microwave Irradiation

Chemical recycling of polyethylene terephthalate (PET) to produce terephthalic acid (TPA) was studied using in situ hydrolysis with sodium methoxide in methanol and dimethyl sulfoxide (DMSO) as solvent under microwave irradiation. The microwave-assisted reaction was carried out at different temperatures, and reaction time between 5 to 30 min. High degrees of depolymerization were examined at temperature near 70°C at microwave power 300 W. The reaction was carried out in a sealed microwave reactor in which the time and temperature were controlled and recorded. The products were mainly monomers such as TPA and ethylene glycol (EG) which were isolated and purified for further analysis. Monomethyl terephthalate, dimethyl terephthalate, and terephthalic acid were formed initially then converted to TPA as a single monomer product. Purified, TPA was analyzed and identified by NMR, TGA, DSC and FTIR. It was observed that the reaction greatly depends on the amount of sodium methoxide, the volume of methanol and DMSO used, the reaction time, and temperature. Compared to conventional heating methods, the time needed to achieve complete degradation of PET was significantly reduced to 5 min by using microwave irradiation and sodium methoxide catalyst. This has led to substantial saving in energy and cost supporting the conclusion that this proposed recycling process is very beneficial for the recycling of PET wastes.

Sodium Methoxide Catalyzed Depolymerization of Waste Polyethylene Terephthalate under Microwave Irradiation

Chemical recycling of polyethylene terephthalate (PET) to produce terephthalic acid (TPA) was studied using in situ hydrolysis with sodium methoxide in methanol and dimethyl sulfoxide (DMSO) as solvent under microwave irradiation. The microwave-assisted reaction was carried out at different temperatures, and reaction time between 5 to 30 min. High degrees of depolymerization were examined at temperature near 70 °C at microwave power 300 W. The reaction was carried out in a sealed microwave reactor in which the time and temperature were controlled and recorded. The products were mainly monomers such as TPA and ethylene glycol (EG) which were isolated and purified for further analysis. Monomethyl terephthalate, dimethyl terephthalate, and terephthalic acid were formed initially then converted to TPA as a single monomer product. Purified, TPA was analyzed and identified by NMR, TGA, DSC and FTIR. It was observed that the reaction greatly depends on the amount of sodium methoxide, the volume of methanol and DMSO used, the reaction time, and temperature. Compared to conventional heating methods, the time needed to achieve complete degradation of PET was significantly reduced to 5 min by using microwave irradiation and sodium methoxide catalyst. This has led to substantial saving in energy and cost supporting thus the conclusion that this proposed recycling process is very beneficial for the recycling of PET wastes.

Transformation of dimethyl phthalate esters (DMPEs) by a marine red yeast Rhodotorula mucilaginosa isolated from deep sea sediments of the Atlantic Ocean

A marine red yeast capable of degrading dimethyl phthalate esters (DMPEs) was isolated from deep-sea sediments of the Atlantic Ocean using enrichment culture technique. The yeast was identified as Rhodotorula mucilaginosa Mar-Y3 based on internal transcribed spacer (ITS) gene sequence analysis. The biochemical degradation pathways of three DMPE isomers, namely dimethyl phthalate (DMP), dimethyl isophthalate (DMI), and dimethyl terephthalate (DMT), were investigated using this yeast. The yeast cannot completely mineralize DMPEs, but can transform them to respective phthalate monoester or phthalic acid. R. mucilaginosa Mar-Y3 also degraded different DMPE isomers through varied metabolism pathways and biodegradation rates. The yeast performed one-step ester hydrolysis with a relatively low degradation rate to transform DMP and DMI to the respective monoester; however, monomethyl phthalate (MMP) and monomethyl isophthalate (MMI) were the dead-end products and further metabolism did not proceed. The yeast carried out sequential ester hydrolysis with a relatively high degradation rate to transform DMT to terephthalic acid (TA) via monomethyl terephthalate (MMT), but TA was resistant to further metabolism. These results suggested that phthalate esterases produced by the deep-sea yeast R. mucilaginosa Mar-Y3 had a very high substrate specificity for different DMPE isomers, and that the degradation of DMPEs by this yeast involved distinct esterases responsible for the hydrolysis of two identical carboxylic ester bonds.

Study of thermal decomposition of a zinc(II) monomethyl terephthalate complex, [Zn(CH3O–CO–C6H4COO)2(OH2)3]·2H2O

In this contribution, we report the thermal decomposition and thermo-X-ray diffraction analyses of a ZnII monomethyl terephthalate complex, [Zn(CH3O–CO–C6H4COO)2(OH2)3]·2H2O. Both XRD and temperature-dependent T-XRD patterns for the title compound in the thermal decomposition process (temperature range 30–300 °C) present diffraction peaks reminiscent of ordered, crystalline structure of the starting complex [Zn(CH3O–CO–C6H4COO)2(OH2)3]·2H2O. Crystallization and coordination water molecules of the title complex are eliminated in successive steps, and then the anhydrous complex decomposes to ZnO (the total experimental mass loss of 84.80 % versus the theoretical mass loss, 84.23 %). The formation of ZnO of wurtzite structure (hexagonal phase, space group P63 mc) as spherical nanoparticles with average size of 58 nm has been confirmed by XRD, SEM and EDX analyses performed on the final product.

Specific detection of intramitochondrial superoxide produced by either cell activation or apoptosis by employing a newly developed cell-permeative lucigenin derivative, 10,10′-dimethyl-9,9′-biacridinium bis(monomethyl terephthalate)

Here we developed a new cell-permeative lucigenin derivative, 10,10′-dimethyl-9,9′-biacridinium bis(monomethyl terephthalate) (MMT), to detect intracellular superoxide production. Both MMT and lucigenin were specific to superoxide among reactive oxygen species tested. Although lucigenin barely penetrated into cells, MMT accumulated in mitochondria in a variety of cells such as neutrophils. By employing MMT, we found that, upon activation of neutrophils with phorbol myristate acetate, superoxide was generated extracellularly as well as intramitochondrially and that such intramitochondrial superoxide production was dependent on oxidative phosphorylation. We also found that, during apoptosis, superoxide was gradually produced in mitochondria in association with phosphatidylserine exposure and that the kinetics of superoxide production was very heterogeneous at the single-cell level. Thus this study demonstrates that MMT could serve as a specific probe for intramitochondrial superoxide in either activated or apoptotic cells.

Solubility of Dimethyl Terephthalate and Monomethyl Terephthalate in the Methanol Aqueous Solution and Its Application To Recycle Monomethyl Terephthalate from Crude Dimethyl Terephthalate

The solubilities of dimethyl terephthalate (DMT) and monomethyl terephthalate (MMT) in methanol aqueous solutions were determined in the temperature range of 280–336 K. The solute-free mass fractions of methanol extended from 0.3 to 1.0. Both the solubilities of DMT and MMT in aqueous methanol solution increase with the temperature and the addition of methanol. The experimental data were correlated with the Wilson and the NRTL models. The root-mean-square deviations for the system of (DMT + methanol + water) were 1.30 and 1.33 K calculated by the Wilson and the NRTL models, respectively, while for the system of (MMT + methanol + water), the root-mean-square deviations were 0.55 and 0.82 K. The melting points and the enthalpy of fusion of DMT and MMT were detected by the differential scanning calorimetry (DSC). A simple purification and recycling process was designed to separate MMT from the esterification reaction product according to the solubility difference between DMT and MMT.

A Novel Alkaline Esterase fromSporosarcinasp. nov. Strain eSP04 Catalyzing the Hydrolysis of a Wide Variety of Aryl-carboxylic Acid Esters

A novel esterase showing activity specific for esters of aryl-carboxylic acids was discovered in Sporosarcina sp. nov., which was identified by the 16S rDNA sequencing method in addition to morphological and physiological analyses. The aryl-carboxylesterase (named EstAC) was purified 780-fold from crude cell extracts by a 5-step procedure. EstAC was characterized as a monomeric protein with a molecular weight of 43,000, an optimum pH of around 9.0, and an optimum temperature of 40 °C. The pH optimum and the effects of inhibitors together with an internal amino acid sequence suggested that EstAC is a member of family VIII esterases. EstAC was found to be highly active on a wide variety of substrates such as alkyl benzoates, alkyl phenylacetates, ethyl α- or β-substituted phenylpropionates, dialkyl terephthalates, dimethyl isophthalate, and ethylene glycol dibenzoate. However, monomethyl terephthalate was not hydrolyzed. It was suggested that EstAC had 4-hydroxybenzoyl and cinnamoyl esterase activities as well.

Comparison of initial hydrolysis of the three dimethyl phthalate esters (DMPEs) by a basidiomycetous yeast, Trichosporon DMI-5-1, from coastal sediment

Dimethyl phthalate esters (DMPEs) are a group of plasticizers commonly detected in the environment with potential adverse human health impact. The degradation of DMPEs by fungal systems has been studied to a limited extent, particularly by yeasts. In this study, a basidiomycetous yeast Trichosporon DMI-5-1 capable of degrading DMPEs was obtained and the degradation pathways were investigated. A DMPE-degrading yeast was isolated from costal sediment by enrichment culture technique and was identified as Trichosporon sp. DMI-5-1 based on microscopic morphology and 18S rDNA sequence. Comparative investigations on biodegradation of three isomers of DMPEs, namely dimethyl phthalate (DMP), dimethyl isophthalate (DMI), and dimethyl terephthalate (DMT), were carried out with this yeast strain. Trichosporon sp. DMI-5-1 could not mineralize DMPEs completely but transform them to respective monomethyl phthalate or phthalic acid. Biochemical degradation pathways for the three DMPE isomers by Trichosporon sp. DMI-5-1 were apparently different. The yeast carried out one-step ester hydrolysis of DMP and DMI to respective monoesters (monomethyl phthalate and monomethyl isophthalate, respectively) and no further metabolism of these two monoesters. Meanwhile, DMT was transformed by the yeast to monomethyl terephthalate and subsequently to terephthalic acid by stepwise hydrolysis of the two ester bonds. This study shows that different catalytic processes are involved in the transformation of DMPEs by the basidiomycetous yeast Trichosporon sp. DMI-5-1 and suggests that its esterases, responsible for the initial hydrolyzing the two ester bonds of DMPEs, are highly substrate specific.

The synthesis of poly(butylene terephthalate) from terephthalic acid, part II: Assessment of the first stage of the polymerization process

AbstractThe production of poly(butylene terephthalate) (PBT) struggles with the formation of substantial amounts of tetrahydrofuran (THF). When PBT is synthesized from terephthalic acid (TPA) instead of dimethyl terephthalate (DMT), even more THF is formed, mainly during the first stage of the melt polymerization process. Although a lot of literature reports on the existence of this side reaction in both processes, to the best of our knowledge, a comparison, which reveals the importance of the acidity and insolubility of TPA on the THF formation, was never described. Finally, an interesting study was performed on the THF formation during the synthesis of PBT from mixtures of DMT and TPA as well as from the completely soluble monomethyl terephthalate (MMT). © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Degradability of dimethyl terephthalate by Variovorax paradoxus T4 and Sphingomonas yanoikuyae DOS01 isolated from deep-ocean sediments

Two strains of bacteria were isolated from deep-ocean sediments of the South China Sea using enrichment culturing technique and they were identified as Sphingomonas yanoikuyae DOS01 (AY878409) and Variovorax paradoxus T4 (AY878410) based on 16S rRNA gene sequences. S. yanoikuyae DOS01 was only capable of transforming dimethyl terephthalate (DMTP) to monomethyl terephthalate (MMTP) without further degradation while V. paradoxus T4 exhibited ability in mineralizing DMTP as the sole source of carbon and energy. The biochemical pathway of DMTP degradation was through MMTP and terephthalic acid (TA) as major detectable degradation intermediates in the culture media by both microorganisms. V. paradoxus T4 utilized DMTP and MMTP via hydrolysis of diester and monoester in the initial steps in degradation as confirmed by total organic carbon analysis of the culture medium and esterase activity assay of the lysed cells and fraction. The specific hydrolysis activity of esterase induced by DMTP or MMTP showed that greater hydrolysis of p-nitrophenyl acetate by esterase induced by DMTP-grown cells than that induced by MMTP. Results of this research suggest that the cleavage of the two identical carboxylic ester groups of phthalate diester are carried out by highly specific esterases of the same bacteria in the environment.

Biodegradation of dimethyl terephthalate by Pasteurella multocida Sa follows an alternative biochemical pathway

Pasteurella multocida Sa, a bacterial strain isolated from mangrove sediment by enrichment technique, was capable of transforming dimethyl terephthalate (DMT). Biodegradation of DMT was shown to take place as a series of sequential steps involving the hydrolysis of two ester linkages between the carboxyl groups of the terephthalate and the methyl side-chain initially to produce mono-methyl terephthalate (MMT) and then terephthalic acid (TA), respectively. However, with ethanol as the carrying solvent, there was a formation of one metabolite previously not observed. The two metabolites were characterized by high performance-liquid chromatography-electron ionization mass spectrometry as MMT and mono-ethyl terephthalate (MET), suggesting the existence of an alternative biochemical pathway in the degradation of DMT by P. multocida Sa. Since the presence of MMT and ethanol in culture inoculated with P. multocida Sa was prerequisites for the formation of MET, biologically mediated trans-esterification was proposed as a mechanism for the novel biochemical process observed.