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Plastics derived from fossil fuels are used ubiquitously owing to their exceptional physicochemical characteristics. However, the extensive and short-term use of plastics has caused environmental challenges. The biotechnological plastic conversion can help address the challenges related to plastic pollution, offering sustainable alternatives that can operate using bioeconomic concepts and promote socioeconomic benefits. In this context, using soil from a plastic-contaminated landfill, two consortia were established (ConsPlastic-A and -B) displaying versatility in developing and consuming polyethylene or polyethylene terephthalate as the carbon source of nutrition. The ConsPlastic-A and -B metagenomic sequencing, taxonomic profiling, and the reconstruction of 79 draft bacterial genomes significantly expanded the knowledge of plastic-degrading microorganisms and enzymes, disclosing novel taxonomic groups associated with polymer degradation. The microbial consortium was utilized to obtain a novel Pseudomonas putida strain (BR4), presenting a striking metabolic arsenal for aromatic compound degradation and assimilation, confirmed by genomic analyses. The BR4 displays the inherent capacity to degrade polyethylene terephthalate (PET) and produce polyhydroxybutyrate (PHB) containing hydroxyvalerate (HV) units that contribute to enhanced copolymer properties, such as increased flexibility and resistance to breakage, compared with pure PHB. Therefore, BR4 is a promising strain for developing a bioconsolidated plastic depolymerization and upcycling process. Collectively, our study provides insights that may extend beyond the artificial ecosystems established during our experiments and supports future strategies for effectively decomposing and valorizing plastic waste. Furthermore, the functional genomic analysis described herein serves as a valuable guide for elucidating the genetic potential of microbial communities and microorganisms in plastic deconstruction and upcycling.

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The enzyme PETase fromIdeonella sakaiensis (IsPETase) strain 201-F6 can catalyze the hydrolysis of polyethylene terephthalate (PET), mainly converting it into mono(2-hydroxyethyl) terephthalic acid (MHET). In this study, we used quantum mechanics/molecular mechanics (QM/MM) simulations to explore the molecular details of the catalytic reaction mechanism of IsPETase in the formation of MHET. The QM region was described with AM1d/PhoT and M06-2X/6-31+G(d,p) potential. QM/MM simulations unveil the complete enzymatic PET hydrolysis mechanism and identify two possible reaction pathways for acylation and deacylation steps. The barrier obtained at M06-2X/6-31+G(d,p)/MM potential for the deacylation step corresponds to 20.4 kcal/mol, aligning with the experimental value of 18 kcal/mol. Our findings indicate that deacylation is the rate-limiting step of the process. Furthermore, per-residue interaction energy contributions revealed unfavorable contributions to the transition state of amino acids located at positions 200-230, suggesting potential sites for targeted mutations. These results can contribute to the development of more active and selective enzymes for PET depolymerization.

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OBJECTIVE: The purpose of this retrospective study was to compare accuracy of arch expansion using two different thermoplastic materials in Invisalign aligners: EX30® (Polyethylene Terephthalate Glycol, or PETG) and SmartTrack® (polyurethane). METHODS: The study sample comprised 65 adult patients consecutively treated with Invisalign from two private practices: group 1 - treated with EX30® (358 teeth) and group 2 - treated with SmartTrack® (888 teeth). Six hundred and twenty-three measurements were assessed in three digital models throughout treatment: model 1 - initial, model 2 - predicted tooth position, and model 3 - achieved position. Sixteen reference points per arch were marked and, after best alignment, 2 points per tooth were copied from one digital model to another. Linear values of both arches were measured for canines, premolars, and first molars: on lingual gingival margins and cusp tips of every tooth. Comparisons were performed by Wilcoxon and Mann-Whitney test. RESULTS: Both termoplastic materials presented significant differences between predicted and achieved values for all measurements, except for the lower molar cusp tip in the SmartTrack® group. There is no statistical difference in the accuracy of transverse expansion between these two materials. Overall accuracy for EX30® aligners in maxilla and mandible were found to be 37 and 38%, respectively; and Smarttrack® presented an overall accuracy of 56.62% in the maxilla and 68.72% in the mandible. CONCLUSIONS: It is not possible to affirm one material expands better than the other. Further controlled clinical studies should be conducted comparing SmartTrack® and EX30® under similar conditions.

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The overwhelming use of PET plastic in various day-to-day activities led to the voluminous increase in PET waste and growing environmental hazards. A plethora of methods have been used that are associated with secondary pollutants. Therefore, microbial degradation of PET provides a sustainable approach due to its versatile metabolic diversity and capacity. The present work highlights the cutinase enzyme's role in PET degradation. This study focuses on the bacterial cutinases homologs screened from 43 reported phylum of bacteria. The reported bacterial cutinases for plastic degradation have been chosen as reference sequences, and 917 sequences have shown homology across the bacterial phyla. The dienelactone hydrolase (DLH) domain was identified for attaining specificity towards PET binding in 196 of 917 sequences. Various computational tools have been used for the physicochemical characterization of 196 sequences. The analysis revealed that most selected sequences are hydrophilic, extracellular, and thermally stable. Based on this analysis, 17 sequences have been further pursued for three-dimensional structure prediction and validation. The molecular docking studies of 17 selected sequences revealed efficient PET binding with the three sequences derived from the phylum Bacteroidota, the lowest binding energy of -5.9 kcal/mol, Armatimonadota, and Nitrososphaerota with -5.8 kcal/mol. The two enzyme sequences retrieved from the phylum Bacteroidota and Armatimonadota are metagenomically derived. Therefore, the present studies concluded that there is a high probability of finding cutinase homologs in various environmental resources that can be further explored for PET degradation.

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The environmental presence of nano- and micro-plastic particles (NMPs) is suspected to have a negative impact on human health. Environmental NMPs are difficult to sample and use in life science research, while commercially available plastic particles are too morphologically uniform. Additionally, this NMPs exposure exhibited biological effects, including cell internalization, oxidative stress, inflammation, cellular adaptation, and genotoxicity. Therefore, developing new methods for producing heterogenous NMPs as observed in the environment is important as reference materials for research. Thus, we aimed to generate and characterize NMPs suspensions using a modified ultrasonic protocol and to investigate their biological effects after exposure to different human cell lines. To this end, we produced polyethylene terephthalate (PET) NMPs suspensions and characterized the particles by dynamic light scattering and scanning electron microscopy. Ultrasound treatment induced polymer degradation into smaller and heterogeneous PET NMPs shape fragments with similar surface chemistry before and after treatment. A polydisperse suspension of PET NMPs with 781 nm in average size and negative surface charge was generated. Then, the PET NMPs were cultured with two human cell lines, A549 (lung) and HaCaT (skin), addressing inhalation and topical exposure routes. Both cell lines interacted with and have taken up PET NMPs as quantified via cellular granularity assay. A549 but not HaCaT cell metabolism, viability, and cell death were affected by PET NMPs. In HaCaT keratinocytes, large PET NMPs provoked genotoxic effects. In both cell lines, PET NMPs exposure affected oxidative stress, cytokine release, and cell morphology, independently of concentration, which we could relate mechanistically to Nrf2 and autophagy activation. Collectively, we present a new PET NMP generation model suitable for studying the environmental and biological consequences of exposure to this polymer.

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Polyethylene terephthalate (PET) is a commonly used thermoplastic in industry due to its excellent malleability and thermal stability, making it extensively employed in packaging manufacturing. Inadequate disposal of PET packaging in the environment and natural physical-chemical processes leads to the formation of smaller particles known as PET micro and nanoplastics (MNPs). The reduced dimensions enhance particle bioavailability and, subsequently, their reactivity. This study involved chemical degradation of PET using trifluoroacetic acid to assess the impact of exposure to varying concentrations of PET MNPs (0.5, 1, 5, 10, and 20 mg/L) on morphological, functional, behavioral, and biochemical parameters during the early developmental stages of zebrafish (Danio rerio). Characterization of the degraded PET revealed the generated microplastics (MPs) ranged in size from 1305 to 2032 µm, and that the generated nanoplastics (NPs) ranged from 68.06 to 955 nm. These particles were then used for animal exposure. After a six-day exposure period, our findings indicate that PET MNPs can diminish spontaneous tail coiling (STC), elevate the heart rate, accumulate on the chorion surface, and reduce interocular distance. These results suggest that PET exposure induces primary toxic effects on zebrafish embryo-larval stage of development.

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Several hydrolases have been described to degrade polyethylene terephthalate (PET) at moderate temperatures ranging from 25°C to 40°C. These mesophilic PET hydrolases (PETases) are less efficient in degrading this plastic polymer than their thermophilic homologs and have, therefore, been the subject of many protein engineering campaigns. However, enhancing their enzymatic activity through rational design or directed evolution poses a formidable challenge due to the need for exploring a large number of mutations. Additionally, evaluating the improvements in both activity and stability requires screening numerous variants, either individually or using high-throughput screening methods. Here, we utilize instead the design of chimeras as a protein engineering strategy to increase the activity and stability of Mors1, an Antarctic PETase active at 25°C. First, we obtained the crystal structure of Mors1 at 1.6 Å resolution, which we used as a scaffold for structure- and sequence-based chimeric design. Then, we designed a Mors1 chimera via loop exchange of a highly divergent active site loop from the thermophilic leaf-branch compost cutinase (LCC) into the equivalent region in Mors1. After restitution of an active site disulfide bond into this chimera, the enzyme exhibited a shift in optimal temperature for activity to 45°C and an increase in fivefold in PET hydrolysis when compared with wild-type Mors1 at 25°C. Our results serve as a proof of concept of the utility of chimeric design to further improve the activity and stability of PETases active at moderate temperatures.

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The excessive consumption of plastic packaging, especially those produced with polyethylene terephthalate (PET), and the fact that most of them are destined for garbage have made such packaging a worrying environmental liability. Their inadequate disposal promotes the pollution of soils, watercourses, and oceans, and even the presence of component materials of these packages in the human body, in the form of microplastics, has been observed. As research in the area advances, greater concerns arise, as more problems arising from the excessive use and disposal of plastics are identified. Looking for an alternative for the destination of this material, a technology was developed for the production of materials with characteristics similar to 3D graphene. This carbon material has qualities and versatility that allow its wide use in several applications and is produced using PET as a carbon precursor. This work presents this production technology with possible variables, the characterization of the produced materials, and their potential applications. For the electronics area, such as supercapacitors, improvement points needed for validation were observed. For application as an adsorbent and use in the treatment of industrial effluents when using sand covered by carbon material, the results demonstrated efficiency. The material proved to be a potential destination for PET, as an alternative to reduce this environmental liability.

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Antimony is present in different types of plastics as a catalyzer residue and/or as a synergistic fire retardant; relatively high concentrations of this element reported in polyethylene terephthalate (PET) bottles and wrappers as well as its migration to the edible products or to different environment compartments are of concern. In this work, Sb determination is such products had been undertaken using hydride generation - microwave plasma - atomic emission spectrometry. To avoid harsh conditions typically reported for the digestion of PET, alkaline methanolysis was introduced whereas water samples were analyzed directly. Another original approach was to perform quantification by partial least squares regression (PLS1), taking spectral data from 2-nm range that comprised two emission lines (217.581 nm and less intense 217.919 nm). For PET, the calibration solutions contained Sb-free digest and covered the Sb concentration range 80-230 µg L-1. For the analysis of water, the calibration range was 0.5-10 µg L-1 and aqueous standard solutions were used. PLS1 provided reliable prediction, eliminating spectral interferences detected in the presence of PET digests and compensating for the spectral changes observed at low Sb concentrations. After standard addition to the real-world samples, the percentage recoveries were in the range 93.8-99.3% and 68-102% for PET and for bottled water, respectively. The method quantification limit for PET was 10 mg kg-1 and for water it corresponded to 0.20 µg L-1. The concentrations of Sb found in the analyzed samples were: 154-279 mg kg-1 for PET bottles and <0.5-5.30 µg L-1 for water.

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Para garantia da segurança dos consumidores muitas decisões na indústria alimentícia são tomadas com "margem de segurança", uma delas é a dispersão de partículas alergênicas em contaminações cruzadas. Em estoques de bebidas embaladas, diversas unidades que não possuem ingredientes alergênicos ou traços são descartadas quando um produto alergênico entra em contato, mesmo que pela parte externa. O presente estudo teve como objetivo avaliar se a partícula alergênica externa migra pela embalagem de PET e contamina a bebida não alergênico. Para isso, um produto em embalagem PET sem ingredientes ou partículas alergênicas (água) teve sua parte externa exposta a um ingrediente alergênico (soja) em meio aquoso e oleoso por 1, 24, 48 e 72 horas, demonstrando que não há migração para a parte interna.

To ensure the safety of consumers, many decisions in the food industry are made with "margin of safety", one is the dispersion of allergenic particles in cross-contamination. In stocks of packaged beverages, several units that do not contain allergenic ingredients or traces are discarded when an allergenic product comes into contact, even out of pack. The objective of this study is to evaluate whether the external allergenic particle migrates through the PET packaging and contaminates the non-allergenic food. A product in PET packaging without allergenic ingredients or particles (water) has your external part exposed to an allergenic ingredient (soy) in an aqueous and oily medium for 1, 24, 48 and 72 hours, and tested if are migration.

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Several microorganisms have been reported as capable of acting on poly(ethylene terephthalate) (PET) to some extent, such as Yarrowia lipolytica, which is a yeast known to produce various hydrolases of industrial interest. The present work aims to evaluate PET depolymerization by Y. lipolytica using two different strategies. In the first one, biocatalysts were produced during solid-state fermentation (SSF-YL), extracted and subsequently used for the hydrolysis of PET and bis(2-hydroxyethyl terephthalate) (BHET), a key intermediate in PET hydrolysis. Biocatalysts were able to act on BHET, yielding terephthalic acid (TPA) (131.31 µmol L-1), and on PET, leading to a TPA concentration of 42.80 µmol L-1 after 168 h. In the second strategy, PET depolymerization was evaluated during submerged cultivations of Y. lipolytica using four different culture media, and the use of YT medium ((w/v) yeast extract 1%, tryptone 2%) yielded the highest TPA concentration after 96 h (65.40 µmol L-1). A final TPA concentration of 94.3 µmol L-1 was obtained on a scale-up in benchtop bioreactors using YT medium. The conversion obtained in bioreactors was 121% higher than in systems with SSF-YL. The results of the present work suggest a relevant role of Y. lipolytica cells in the depolymerization process.

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We assessed microplastics (MPs) contamination in water, sediments, and tissues (gills, digestive tract, and muscle) of two intertidal crab species with different ecological traits and commercial importance (Menippe mercenaria and Callinectes sapidus), from a coastal lagoon in the southeastern Gulf of Mexico. There were significant differences between MP abundances in the abiotic matrices and between crab species. The burrower, sedentary and carnivorous M. mercenaria bioaccumulates 50 % more MPs than the free-swimming, omnivorous C. sapidus. However, no differences were observed between species' tissues. Fragments were the predominant shape in the tissues of both species, with the exception in the digestive tract of M. mercenaria. We identified polyethylene, and polyethylene terephthalate in water samples and Silopren® in sediment. In both crab species, Silopren and polyethylene predominated. Differences in ecological traits resulted in different bioaccumulation patterns in intertidal crabs.

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Poly(ethylene terephthalate) (PET) is one of the main synthetic plastics produced worldwide. The extensive use of this polymer causes several problems due to its low degradability. In this scenario, biocatalysts dawn as an alternative to enhance PET recycling. The enzymatic hydrolysis of PET results in a mixture of terephthalic acid (TPA), ethylene glycol (EG), mono-(2-hydroxyethyl) terephthalate (MHET) and bis-(2-hydroxyethyl) terephthalate (BHET) as main products. This work developed a new methodology to quantify the hydrolytic activity of biocatalysts, using BHET as a model substrate. The protocol can be used in screening enzymes for PET depolymerization reactions, amongst other applications. The very good fitting (R2 = 0.993) between experimental data and the mathematical model confirmed the feasibility of the Michaelis-Menten equation to analyze the effect of BHET concentration (8-200 mmol L-1) on initial hydrolysis rate catalyzed by Humicola insolens cutinase (HiC). In addition to evaluating the effects of enzyme and substrate concentration on the enzymatic hydrolysis of BHET, a novel and straightforward method for MHET synthesis was developed using an enzyme load of 0.025 gprotein gBHET-1 and BHET concentration of 60 mmol L-1 at 40 °C. MHET was synthesized with high selectivity (97 %) and yield (82 %). The synthesized MHET properties were studied using differential scanning calorimetry (DSC), thermogravimetry (TGA), and proton nuclear magnetic resonance (1H NMR), observing the high purity of the final product (86.7 %). As MHET is not available commercially, this synthesis using substrate and enzyme from open suppliers adds new perspectives to monitoring PET hydrolysis reactions.

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While atmospheric microplastics have attracted scientific attention as a significant source of microplastic contamination in the environment, studies in large population centers remain sparse. Here we present the first report on the occurrence and distribution of atmospheric microplastics in Mexico City (Latin America's second most densely populated city), collected using PM10 and PM2.5 active samplers at seven monitoring stations (urban, residential, and industrial) during the dry and wet seasons of 2020. The results showed that microplastics were detected in all of the samples examined, with mean microplastic concentrations (items m-3) of 0.205 ± 0.061 and 0.110 ± 0.055 in PM10 and PM2.5, respectively. The spatial distribution of microplastics showed seasonal variation, with greater abundances in locations closer to industrial and urban centers. There was also a significant difference in microplastic concentrations in PM10 and PM2.5 between the dry and wet seasons. The mean PM2.5/PM10 ratio was 0.576, implying that microplastics were partitioned more towards PM2.5 than PM10 in Mexico City. Fibers were the most prominent shape (>75 %), and blue was the most common color (>60 %). The size characteristics indicated microplastics of varying lengths, ranging from 39 to 5000 µm, with 66 % being <500 µm. Metal contaminants such as aluminum, iron, and titanium were detected using SEM-EDX on randomly selected microplastics. The microplastics were identified as cellophane, polyethylene, polyethylene terephthalate, polyamide, and cellulose (rayon) using ATR-FTIR spectral analysis. Our findings unravel the extent and characteristics of atmospheric microplastics in the Mexico City metropolitan area, which will aid future research to better understand their fate, transport, and potential health risks, demanding more investigations and close monitoring.

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Cachaça is a beverage of great cultural and economic importance for Brazil. It is made up of several substances that are responsible for the flavor of the beverage. Countless substances of a toxic nature can also be present, such as polycyclic aromatic hydrocarbons (PAHs). These contaminants are commonly found in beverages and food. They have been studied because their toxicity is related to their mutagenic and carcinogenic properties, and they pose a risk to human health. The PAHs can be formed in cachaça during different stages of processing. In this work, the presence of PAHs (naphthalene, acenaphene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benzo[a]anthracene, acephenylene, and benzo[a]pyrene) was investigated during the storage of the beverage in plastic containers. Thus, samples from five producers of cachaça in the state of Minas Gerais were stored for up to 8 months in polyethylene terephthalate (PET) packaging from three different manufacturers. Samples stored for 4 and 8 months were analyzed by high-performance liquid chromatography, and 10 PAHs (naphthalene, acenaphene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benzo[a]anthracene, acephenylene, and benzo[a]pyrene) were identified and quantified. An increase in PAH concentration in cachaça samples with the storage time in plastic containers was observed. The three different packages contributed to the contamination of the cachaça samples with different PAHs. The highest concentration (approximately 11.0 µg L-1 ) of fluorene was observed in sample A from the three packages and during the two storage times. Thus, it can be inferred that the storage of cachaça in bottles of PET is inadequate for maintaining the quality of the beverage. PRACTICAL APPLICATION: Therefore, it can be inferred from the results of the analysis that PET packages are sources of PAHs, and the storage time in these packages contributed to the increase in the concentration of these contaminants in the beverage. These results suggest that a review of the legislation regarding the use of PET packaging for beverage storage is necessary, as these compounds are carcinogenic.

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The contamination of water by pharmaceutical pollutants is a major issue these days due to excessive use of these ingredients in modern life. This study evaluated the adsorption and effectiveness of a low-cost composite prepared from heavy sugarcane ash (HSA) fused with polyethylene terephthalate (PET) and functionalized with iron (Fe3+) in a dynamic system through a fixed-bed column. The solution of synthetic drugs was prepared and placed in a reservoir, using a peristaltic pump the solution is run onto the fixed bed column at a flow rate of 2 mL min-1. Saturation time and adsorption capacity were evaluated by centrifugation and extraction after a regular interval of 2 h from the adsorption column. The samples were analyzed using high-performance liquid chromatography (HPLC) and the data was modeled for quantification. For DIC removal, an adsorption capacity of 324.34 µg. g-1 and a saturation time of 22 h were observed, while the adsorption capacity of NAP was 956.49 µg. g-1, with a saturation time of 8 h. Thus, the PETSCA/Fe3+ adsorbent proved to be quite efficient for removing the pharmaceutical pollutants, with a longer period of operation for DIC removal. These findings suggested that a highly efficient bed column made from a less expensive waste material and could be used to remove hazardous pharmaceutical contaminants.

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This research aimed to evaluate the effect of adding different polymeric waste percentages and types on the physical, mechanical, thermal, and durability properties of soil-cement bricks. Tire and polyethylene terephthalate (PET) waste were evaluated at 1.5 and 3.0% (mass/mass). The soil was characterized in terms of shrinkage, compaction, consistency limits, particle size, and chemical analyses, whereas the waste particles were submitted to morphological characterization. The bricks were produced in an automatic press with a 90:10 (mass/mass) soil:cement ratio. The soil-cement bricks were characterized by density, moisture, water absorption, loss of mass by immersion, compressive strength, thermal conductivity, and microstructural analysis. PET waste stood out for its use as reinforcement in soil-cement bricks. The best performance was obtained for bricks reinforced with 1.5% PET, which showed a significant compressive strength improvement, meeting the marketing standards criteria, even after the durability test, as well as obtaining the lowest thermal conductivity values. The percentage increase from 1.5 to 3.0% fostered a significant water absorption and loss of mass increase, as well as a significant compressive strength reduction of the bricks.

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Polyethylene terephthalate (PET) is one of the most widely used synthetic plastics in the packaging industry, and consequently has become one of the main components of plastic waste found in the environment. However, several microorganisms have been described to encode enzymes that catalyze the depolymerization of PET. While most known PET hydrolases are thermophilic and require reaction temperatures between 60°C and 70°C for an efficient hydrolysis of PET, a partial hydrolysis of amorphous PET at lower temperatures by the polyester hydrolase IsPETase from the mesophilic bacterium Ideonella sakaiensis has also been reported. We show that polyester hydrolases from the Antarctic bacteria Moraxella sp. strain TA144 (Mors1) and Oleispira antarctica RB-8 (OaCut) were able to hydrolyze the aliphatic polyester polycaprolactone as well as the aromatic polyester PET at a reaction temperature of 25°C. Mors1 caused a weight loss of amorphous PET films and thus constitutes a PET-degrading psychrophilic enzyme. Comparative modeling of Mors1 showed that the amino acid composition of its active site resembled both thermophilic and mesophilic PET hydrolases. Lastly, bioinformatic analysis of Antarctic metagenomic samples demonstrated that members of the Moraxellaceae family carry candidate genes coding for further potential psychrophilic PET hydrolases. IMPORTANCE A myriad of consumer products contains polyethylene terephthalate (PET), a plastic that has accumulated as waste in the environment due to its long-term stability and poor waste management. One promising solution is the enzymatic biodegradation of PET, with most known enzymes only catalyzing this process at high temperatures. Here, we bioinformatically identified and biochemically characterized an enzyme from an Antarctic organism that degrades PET at 25°C with similar efficiency to the few PET-degrading enzymes active at moderate temperatures. Reasoning that Antarctica harbors other PET-degrading enzymes, we analyzed available data from Antarctic metagenomic samples and successfully identified other potential enzymes. Our findings contribute to increasing the repertoire of known PET-degrading enzymes that are currently being considered as biocatalysts for the biological recycling of plastic waste.

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O osteossarcoma é uma das neoplasias ósseas mais comumente relatadas na medicina veterinária, principalmente em cães de raça grande e gigante, sendo que a forma vertebral possui importante cenário clínico apresentando 5% do total de relatos. Este possui um prognóstico desfavorável e tempo de sobrevida pequeno. A apresentação clínica é variável e podem ser observados sinais de dor intensa a déficits neurológicos em decorrência do envolvimento medular progressivo. O diagnóstico pode ser realizado por imagens através de radiografia ou tomografia computadorizada, e por análises laboratoriais de citopatologia ou histopatologia, sendo o último preferível para classificação de tumores. A ressecção tumoral parcial é uma forma paliativa de tratamento, indicada em alguns casos para aliviar temporariamente os sinais clínicos relacionados a dor e déficits neurológicos. Contudo, quando há possibilidade terapêutica, a excisão completa fornece melhor prognóstico e tempo de sobrevida, principalmente quando associada a quimioterapia ou radioterapia. Mediante procedimento de vertebrectomia, a estabilização cirúrgica é necessária, podendo ser realizada respeitando os princípios para estabilização vertebral por trauma, sendo necessária a colocação de um espaçador vertebral para evitar o colabamento medular. Diversos materiais foram propostos para a confecção do espaçador vertebral. A manufatura aditiva, também conhecida como impressão 3D, tem transformado o conceito de prototipagem rápida em realidade, devido a habilidade de fabricar peças geométricas específicas de alta complexidade e de forma rápida, permitindo elaborar protótipos para uso pré ou transoperatórios em cirurgias ortopédicas de alta complexidade. O polietileno tereftalato glicol (PETG), por ser um termoplástico de alta resistência, não-biodegradável, biocompatível e de baixo custo é foco desse trabalho no desenvolvimento do espaçador vertebral como estabilizador em um procedimento de vertebrectomia em cão.

Osteosarcoma is one of the most commonly reported bone neoplasms in veterinary medicine, especially in large and giant breed dogs, and the vertebral form has an important clinical scenario presenting 5% of the total reports. This has an unfavorable prognosis and a short survival time. The clinical presentation is variable and signs of severe pain to neurological deficits can be observed as a result of progressive spinal cord involvement. The diagnosis can be made by imaging with radiography or computed tomography, and by laboratory analysis of cytopathology or histopathology, the latter being preferable for tumor classification. Partial tumor resection is a palliative form of treatment, indicated in some cases to temporarily relieve clinical signs related to pain and neurological deficits. However, when there is therapeutic possibility, complete excision provides better prognosis and survival time, especially when associated with chemotherapy or radiotherapy. Through the vertebrectomy procedure, surgical stabilization is necessary and can be performed following the principles for vertebral stabilization due to trauma, with the placement of a vertebral spacer being necessary to prevent spinal collapse. Several materials have been proposed for the manufacture of the spinal spacer. Additive manufacturing, also known as 3D printing, has transformed the concept of rapid prototyping into reality, due to its ability to quickly manufacture specific geometric parts of high complexity, allowing the elaboration of prototypes for pre- or trans-operative use in highly complex orthopedic surgeries. Polyethylene terephthalate glycol (PETG), being a high-strength, non-biodegradable, biocompatible and low-cost thermoplastic, is the focus of this work in the development of the vertebral spacer as a stabilizer in a vertebrectomy procedure in a dog.

El osteosarcoma es una de las neoplasias óseas más comúnmente reportadas en medicina veterinaria, principalmente en perros de raza grande y gigante, siendo que la forma vertebral tiene importante escenario clínico presentando el 5% del total de reportes. Tiene un pronóstico desfavorable y un tiempo de supervivencia corto. La presentación clínica es variable y pueden observarse desde signos de dolor intenso hasta déficits neurológicos como resultado de la afectación medular progresiva. El diagnóstico puede realizarse mediante imágenes con radiografía o tomografía computarizada, y mediante análisis de laboratorio de citopatología o histopatología, siendo este último preferible para la clasificación del tumor. La resección parcial del tumor es una forma de tratamiento paliativo, indicada en algunos casos para aliviar temporalmente los signos clínicos relacionados con el dolor y los déficits neurológicos. Sin embargo, cuando hay posibilidad terapéutica, la escisión completa proporciona un mejor pronóstico y tiempo de supervivencia, principalmente cuando se asocia con quimioterapia o radioterapia. Mediante el procedimiento de la vertebrectomía, es necesaria la estabilización quirúrgica, que puede realizarse respetando los principios para la estabilización vertebral por traumatismo, siendo necesaria la colocación de un espaciador vertebral para evitar el colapso medular. Se han propuesto varios materiales para la fabricación del espaciador vertebral. La fabricación aditiva, también conocida como impresión 3D, ha transformado el concepto de prototipado rápido en una realidad, debido a la capacidad de fabricar piezas geométricas específicas de gran complejidad y con rapidez, lo que permite la elaboración de prototipos para su uso pre o trans-operatorio en cirugías ortopédicas de gran complejidad. El polietileno tereftalato glicol (PETG), por ser un termoplástico de alta resistencia, no biodegradable, biocompatible y de bajo costo es el foco de este trabajo en el desarrollo del espaciador vertebral como estabilizador en un procedimiento de vertebrectomía en un perro.

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The environmental impact arising from poly(ethylene terephthalate) (PET) waste is notable worldwide. Enzymatic PET hydrolysis can provide chemicals that serve as intermediates for value-added product synthesis and savings in the resources. In the present work, some reaction parameters were evaluated on the hydrolysis of post-consumer PET (PC-PET) using a cutinase from Humicola insolens (HiC). The increase in PC-PET specific area leads to an 8.5-fold increase of the initial enzymatic hydrolysis rate (from 0.2 to 1.7 mmol L-1 h-1), showing that this parameter plays a crucial role in PET hydrolysis reaction. The effect of HiC concentration was investigated, and the enzymatic PC-PET hydrolysis kinetic parameters were estimated based on three different mathematical models describing heterogeneous biocatalysis. The model that best fits the experimental data (R2 = 0.981) indicated 1.68 mgprotein mL-1 as a maximum value of the enzyme concentration to optimize the reaction rate. The HiC thermal stability was evaluated, considering that it is a key parameter for its efficient use in PET degradation. The enzyme half-life was shown to be 110 h at 70 ºC and pH 7.0, which outperforms most of the known enzymes displaying PET hydrolysis activity. The results evidence that HiC is a very promising biocatalyst for efficient PET depolymerization.

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