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1.
Appl Microbiol Biotechnol ; 108(1): 404, 2024 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-38953996

RESUMO

Polyethylene terephthalate (PET) is a major component of plastic waste. Enzymatic PET hydrolysis is the most ecofriendly recycling technology. The biorecycling of PET waste requires the complete depolymerization of PET to terephthalate and ethylene glycol. The history of enzymatic PET depolymerization has revealed two critical issues for the industrial depolymerization of PET: industrially available PET hydrolases and pretreatment of PET waste to make it susceptible to full enzymatic hydrolysis. As none of the wild-type enzymes can satisfy the requirements for industrialization, various mutational improvements have been performed, through classical technology to state-of-the-art computational/machine-learning technology. Recent engineering studies on PET hydrolases have brought a new insight that flexibility of the substrate-binding groove may improve the efficiency of PET hydrolysis while maintaining sufficient thermostability, although the previous studies focused only on enzymatic thermostability above the glass transition temperature of PET. Industrial biorecycling of PET waste is scheduled to be implemented, using micronized amorphous PET. Next stage must be the development of PET hydrolases that can efficiently degrade crystalline parts of PET and expansion of target PET materials, not only bottles but also textiles, packages, and microplastics. This review discusses the current status of PET hydrolases, their potential applications, and their profespectal goals. KEY POINTS: • PET hydrolases must be thermophilic, but their operation must be below 70 °C • Classical and state-of-the-art engineering approaches are useful for PET hydrolases • Enzyme activity on crystalline PET is most expected for future PET biorecycling.


Assuntos
Hidrolases , Polietilenotereftalatos , Polietilenotereftalatos/metabolismo , Polietilenotereftalatos/química , Hidrolases/metabolismo , Hidrolases/química , Hidrolases/genética , Hidrólise , Engenharia de Proteínas/métodos , Biodegradação Ambiental , Reciclagem
2.
Dental Press J Orthod ; 29(2): e2423212, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38865514

RESUMO

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.


Assuntos
Desenho de Aparelho Ortodôntico , Polietilenotereftalatos , Poliuretanos , Técnicas de Movimentação Dentária , Humanos , Estudos Retrospectivos , Adulto , Feminino , Técnicas de Movimentação Dentária/instrumentação , Masculino , Poliuretanos/uso terapêutico , Polietilenoglicóis , Arco Dental , Aparelhos Ortodônticos Removíveis , Adulto Jovem
3.
World J Microbiol Biotechnol ; 40(8): 247, 2024 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-38904858

RESUMO

Phthalate isomers are key intermediates in the biodegradation of pollutants including waste polyethylene terephthalate (PET) plastics and plasticizers. So far, an increasing number of phthalate isomer-degrading strains have been isolated, and their degradation pathways show significant diversity. In this paper, we comprehensively review the current status of research on the degrading bacteria, degradation characteristics, aerobic and anaerobic degradation pathways, and degradation genes (clusters) of phthalate isomers, and discuss the current shortcomings and challenges. Moreover, the degradation process of phthalate isomers produces many important aromatic precursor molecules, which can be used to produce higher-value derivative chemicals, and the modification of their degradation pathways holds good prospects. Therefore, this review also highlights the current progress made in modifying the phthalate isomer degradation pathway and explores its potential for high-value applications.


Assuntos
Bactérias , Biodegradação Ambiental , Ácidos Ftálicos , Ácidos Ftálicos/metabolismo , Bactérias/metabolismo , Bactérias/genética , Bactérias/classificação , Isomerismo , Plastificantes/metabolismo , Poluentes Ambientais/metabolismo , Redes e Vias Metabólicas , Polietilenotereftalatos/metabolismo , Polietilenotereftalatos/química
4.
Sci Rep ; 14(1): 14449, 2024 06 24.
Artigo em Inglês | MEDLINE | ID: mdl-38914665

RESUMO

As genomic databases expand and artificial intelligence tools advance, there is a growing demand for efficient characterization of large numbers of proteins. To this end, here we describe a generalizable pipeline for high-throughput protein purification using small-scale expression in E. coli and an affordable liquid-handling robot. This low-cost platform enables the purification of 96 proteins in parallel with minimal waste and is scalable for processing hundreds of proteins weekly per user. We demonstrate the performance of this method with the expression and purification of the leading poly(ethylene terephthalate) hydrolases reported in the literature. Replicate experiments demonstrated reproducibility and enzyme purity and yields (up to 400 µg) sufficient for comprehensive analyses of both thermostability and activity, generating a standardized benchmark dataset for comparing these plastic-degrading enzymes. The cost-effectiveness and ease of implementation of this platform render it broadly applicable to diverse protein characterization challenges in the biological sciences.


Assuntos
Escherichia coli , Robótica , Robótica/métodos , Escherichia coli/genética , Engenharia de Proteínas/métodos , Ensaios de Triagem em Larga Escala/métodos , Ensaios de Triagem em Larga Escala/economia , Hidrolases/metabolismo , Hidrolases/química , Hidrolases/genética , Polietilenotereftalatos/química , Reprodutibilidade dos Testes
5.
Ecotoxicol Environ Saf ; 280: 116540, 2024 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-38833982

RESUMO

The widespread utilization of polyethylene terephthalate (PET) has caused a variety of environmental and health problems. Compared with traditional thermomechanical or chemical PET cycling, the biodegradation of PET may offer a more feasible solution. Though the PETase from Ideonalla sakaiensis (IsPETase) displays interesting PET degrading performance under mild conditions; the relatively low thermal stability of IsPETase limits its practical application. In this study, enzyme-catalysed PET degradation was investigated with the promising IsPETase mutant HotPETase (HP). On this basis, a carbohydrate-binding module from Bacillus anthracis (BaCBM) was fused to the C-terminus of HP to construct the PETase mutant (HLCB) for increased PET degradation. Furthermore, to effectively improve PET accessibility and PET-degrading activity, the truncated outer membrane hybrid protein (FadL) was used to expose PETase and BaCBM on the surface of E. coli (BL21with) to develop regenerable whole-cell biocatalysts (D-HLCB). Results showed that, among the tested small-molecular weight ester compounds (p-nitrophenyl phosphate (pNPP), p-Nitrophenyl acetate (pNPA), 4-Nitrophenyl butyrate (pNPB)), PETase displayed the highest hydrolysing activity against pNPP. HP displayed the highest catalytic activity (1.94 µM(p-NP)/min) at 50 °C and increased longevity at 40 °C. The fused BaCBM could clearly improve the catalytic performance of PETase by increasing the optimal reaction temperature and improving the thermostability. When HLCB was used for PET degradation, the yield of monomeric products (255.7 µM) was ∼25.5 % greater than that obtained after 50 h of HP-catalysed PET degradation. Moreover, the highest yield of monomeric products from the D-HLCB-mediated system reached 1.03 mM. The whole-cell catalyst D-HLCB displayed good reusability and stability and could maintain more than 54.6 % of its initial activity for nine cycles. Finally, molecular docking simulations were utilized to investigate the binding mechanism and the reaction mechanism of HLCB, which may provide theoretical evidence to further increase the PET-degrading activities of PETases through rational design. The proposed strategy and developed variants show potential for achieving complete biodegradation of PET under mild conditions.


Assuntos
Biodegradação Ambiental , Burkholderiales , Escherichia coli , Polietilenotereftalatos , Polietilenotereftalatos/química , Polietilenotereftalatos/metabolismo , Burkholderiales/enzimologia , Escherichia coli/genética , Bacillus anthracis/enzimologia , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/química , Engenharia de Proteínas
6.
J Hazard Mater ; 474: 134838, 2024 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-38850944

RESUMO

Microplastics (MPs) pose an emerging threat to soil ecological function, yet effective solutions remain limited. This study introduces a novel approach using magnetic biochar immobilized PET hydrolase (MB-LCC-FDS) to degrade soil polyethylene terephthalate microplastics (PET-MPs). MB-LCC-FDS exhibited a 1.68-fold increase in relative activity in aquatic solutions and maintained 58.5 % residual activity after five consecutive cycles. Soil microcosm experiment amended with MB-LCC-FDS observed a 29.6 % weight loss of PET-MPs, converting PET into mono(2-hydroxyethyl) terephthalate (MHET). The generated MHET can subsequently be metabolized by soil microbiota to release terephthalic acid. The introduction of MB-LCC-FDS shifted the functional composition of soil microbiota, increasing the relative abundances of Microbacteriaceae and Skermanella while reducing Arthobacter and Vicinamibacteraceae. Metagenomic analysis revealed that MB-LCC-FDS enhanced nitrogen fixation, P-uptake and transport, and organic-P mineralization in PET-MPs contaminated soil, while weakening the denitrification and nitrification. Structural equation model indicated that changes in soil total carbon and Simpson index, induced by MB-LCC-FDS, were the driving factors for soil carbon and nitrogen transformation. Overall, this study highlights the synergistic role of magnetic biochar-immobilized PET hydrolase and soil microbiota in degrading soil PET-MPs, and enhances our understanding of the microbiome and functional gene responses to PET-MPs and MB-LCC-FDS in soil systems.


Assuntos
Carvão Vegetal , Hidrolases , Fósforo , Polietilenotereftalatos , Microbiologia do Solo , Poluentes do Solo , Hidrolases/metabolismo , Polietilenotereftalatos/química , Polietilenotereftalatos/metabolismo , Poluentes do Solo/metabolismo , Carvão Vegetal/química , Fósforo/metabolismo , Fósforo/química , Microplásticos/toxicidade , Biodegradação Ambiental , Enzimas Imobilizadas/metabolismo , Enzimas Imobilizadas/química , Nitrogênio/metabolismo , Ciclo do Nitrogênio , Microbiota/efeitos dos fármacos , Bactérias/genética , Bactérias/metabolismo , Bactérias/efeitos dos fármacos
7.
Biochemistry ; 63(13): 1599-1607, 2024 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-38907702

RESUMO

Small-scale bioreactors that are affordable and accessible would be of major benefit to the research community. In previous work, an open-source, automated bioreactor system was designed to operate up to the 30 mL scale with online optical monitoring, stirring, and temperature control, and this system, dubbed Chi.Bio, is now commercially available at a cost that is typically 1-2 orders of magnitude less than commercial bioreactors. In this work, we further expand the capabilities of the Chi.Bio system by enabling continuous pH monitoring and control through hardware and software modifications. For hardware modifications, we sourced low-cost, commercial pH circuits and made straightforward modifications to the Chi.Bio head plate to enable continuous pH monitoring. For software integration, we introduced closed-loop feedback control of the pH measured inside the Chi.Bio reactors and integrated a pH-control module into the existing Chi.Bio user interface. We demonstrated the utility of pH control through the small-scale depolymerization of the synthetic polyester, poly(ethylene terephthalate) (PET), using a benchmark cutinase enzyme, and compared this to 250 mL bioreactor hydrolysis reactions. The results in terms of PET conversion and rate, measured both by base addition and product release profiles, are statistically equivalent, with the Chi.Bio system allowing for a 20-fold reduction of purified enzyme required relative to the 250 mL bioreactor setup. Through inexpensive modifications, the ability to conduct pH control in Chi.Bio reactors widens the potential slate of biochemical reactions and biological cultivations for study in this system, and may also be adapted for use in other bioreactor platforms.


Assuntos
Reatores Biológicos , Polietilenotereftalatos , Polietilenotereftalatos/química , Polietilenotereftalatos/metabolismo , Concentração de Íons de Hidrogênio , Hidrólise , Hidrolases de Éster Carboxílico/metabolismo , Hidrolases de Éster Carboxílico/química , Burkholderiales/enzimologia , Burkholderiales/metabolismo , Software
8.
Int J Biol Macromol ; 273(Pt 1): 133049, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38857727

RESUMO

To enhance the enzymatic digestibility of polyethylene terephthalate (PET), which is highly oriented and crystallized, a polyethylene glycol (PEG) surfactant of varying molecular weights was utilized to improve the stability of mutant cutinase from Humicola insolens (HiC) and to increase the accessibility of the enzyme to the substrate. Leveraging the optimal conditions for HiC hydrolysis of PET, the introduction of 1 % w/v PEG significantly increased the yield of PET hydrolysis products. PEG600 was particularly effective, increasing the yield by 64.58 % compared to using HiC alone. Moreover, the mechanisms by which PEG600 and PEG6000 enhance enzyme digestion were extensively examined using circular dichroism and fluorescence spectroscopy. The results from CD and fluorescence analyses indicated that PEG alters the protein conformation, thereby affecting the catalytic effect of the enzyme. Moreover, PEG improved the affinity between HiC and PET by lowering the surface tension of the solution, substantially enhancing PET hydrolysis. This study suggests that PEG holds considerable promise as an enzyme protector, significantly aiding in the hydrophilic modification and degradation of PET in an environmentally friendly and sustainable manner.


Assuntos
Hidrolases de Éster Carboxílico , Polietilenoglicóis , Polietilenotereftalatos , Tensoativos , Polietilenotereftalatos/química , Polietilenoglicóis/química , Hidrólise , Tensoativos/química , Hidrolases de Éster Carboxílico/química , Hidrolases de Éster Carboxílico/metabolismo
9.
J Environ Manage ; 363: 121360, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38850902

RESUMO

Large-volume production of poly(ethylene terephthalate) (PET), especially in the form of bottles and food packaging containers, causes problems with polymer waste management. Waste PET could be recycled thermally, mechanically or chemically and the last method allows to obtain individual monomers, but most often it is carried out in the presence of homogeneous catalysts, that are difficult to separate and reuse. In view of this, this work reports for the first time, application of bimetallic MOF-74 - as heterogeneous catalyst - for depolymerization of PET with high monomer (bishydroxyethyl terephthalate, BHET) recovery. The effect of type and amount of second metal in the MOF-74 (Mg/M) was systematically investigated. The results showed increased activity of MOF-74 (Mg/M) containing Co2+, Zn2+ and Mn2+ as a second metal, while the opposite correlation was observed for Cu2+ and Ni2+. It was found that the highest catalytic activity was demonstrated by the introduction of Mg-Mn into MOF-74 with ratio molar 1:1, which resulted in complete depolymerization of PET and 91.8% BHET yield within 4 h. Furthermore, the obtained catalyst showed good stability in 5 reaction cycles and allowed to achieve high-purity BHET, which was confirmed by HPLC analysis. The as-prepared MOF-74 (Mg/Mn) was easy to separate from the post-reaction mixture, clean and reuse in the next depolymerization reaction.


Assuntos
Polietilenotereftalatos , Catálise , Polietilenotereftalatos/química , Polimerização , Gerenciamento de Resíduos/métodos , Reciclagem , Estruturas Metalorgânicas/química
10.
Commun Biol ; 7(1): 725, 2024 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-38867087

RESUMO

The rising use of plastic results in an appalling amount of waste which is scattered into the environment. One of these plastics is PET which is mainly used for bottles. We have identified and characterized an esterase from Streptomyces, annotated as LipA, which can efficiently degrade the PET-derived oligomer BHET. The Streptomyces coelicolor ScLipA enzyme exhibits varying sequence similarity to several BHETase/PETase enzymes, including IsPETase, TfCut2, LCC, PET40 and PET46. Of 96 Streptomyces strains, 18% were able to degrade BHET via one of three variants of LipA, named ScLipA, S2LipA and S92LipA. SclipA was deleted from S. coelicolor resulting in reduced BHET degradation. Overexpression of all LipA variants significantly enhanced BHET degradation. All variants were expressed in E. coli for purification and biochemical analysis. The optimum conditions were determined as pH 7 and 25 °C for all variants. The activity on BHET and amorphous PET film was investigated. S2LipA efficiently degraded BHET and caused roughening and indents on the surface of PET films, comparable to the activity of previously described TfCut2 under the same conditions. The abundance of the S2LipA variant in Streptomyces suggests an environmental advantage towards the degradation of more polar substrates including these polluting plastics.


Assuntos
Streptomyces , Streptomyces/enzimologia , Streptomyces/genética , Microbiologia do Solo , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/química , Biodegradação Ambiental , Streptomyces coelicolor/enzimologia , Streptomyces coelicolor/genética , Esterases/metabolismo , Esterases/genética , Esterases/química , Polietilenotereftalatos/metabolismo
11.
Microb Ecol ; 87(1): 88, 2024 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-38943017

RESUMO

Plastic pollution poses a worldwide environmental challenge, affecting wildlife and human health. Assessing the biodegradation capabilities of natural microbiomes in environments contaminated with microplastics is crucial for mitigating the effects of plastic pollution. In this work, we evaluated the potential of landfill leachate (LL) and estuarine sediments (ES) to biodegrade polyethylene (PE), polyethylene terephthalate (PET), and polycaprolactone (PCL), under aerobic, anaerobic, thermophilic, and mesophilic conditions. PCL underwent extensive aerobic biodegradation with LL (99 ± 7%) and ES (78 ± 3%) within 50-60 days. Under anaerobic conditions, LL degraded 87 ± 19% of PCL in 60 days, whereas ES showed minimal biodegradation (3 ± 0.3%). PE and PET showed no notable degradation. Metataxonomics results (16S rRNA sequencing) revealed the presence of highly abundant thermophilic microorganisms assigned to Coprothermobacter sp. (6.8% and 28% relative abundance in anaerobic and aerobic incubations, respectively). Coprothermobacter spp. contain genes encoding two enzymes, an esterase and a thermostable monoacylglycerol lipase, that can potentially catalyze PCL hydrolysis. These results suggest that Coprothermobacter sp. may be pivotal in landfill leachate microbiomes for thermophilic PCL biodegradation across varying conditions. The anaerobic microbial community was dominated by hydrogenotrophic methanogens assigned to Methanothermobacter sp. (21%), pointing at possible syntrophic interactions with Coprothermobacter sp. (a H2-producer) during PCL biodegradation. In the aerobic experiments, fungi dominated the eukaryotic microbial community (e.g., Exophiala (41%), Penicillium (17%), and Mucor (18%)), suggesting that aerobic PCL biodegradation by LL involves collaboration between fungi and bacteria. Our findings bring insights on the microbial communities and microbial interactions mediating plastic biodegradation, offering valuable perspectives for plastic pollution mitigation.


Assuntos
Bactérias , Biodegradação Ambiental , Microbiota , Microplásticos , Instalações de Eliminação de Resíduos , Microplásticos/metabolismo , Bactérias/classificação , Bactérias/metabolismo , Bactérias/genética , Bactérias/isolamento & purificação , Poluentes Químicos da Água/metabolismo , Poliésteres/metabolismo , Sedimentos Geológicos/microbiologia , RNA Ribossômico 16S/genética , Estuários , Polietileno/metabolismo , Polietilenotereftalatos/metabolismo
12.
Biochemistry ; 63(13): 1663-1673, 2024 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-38885634

RESUMO

The mono(2-hydroxyethyl) terephthalate hydrolase (MHETase) from Ideonella sakaiensis carries out the second step in the enzymatic depolymerization of poly(ethylene terephthalate) (PET) plastic into the monomers terephthalic acid (TPA) and ethylene glycol (EG). Despite its potential industrial and environmental applications, poor recombinant expression of MHETase has been an obstacle to its industrial application. To overcome this barrier, we developed an assay allowing for the medium-throughput quantification of MHETase activity in cell lysates and whole-cell suspensions, which allowed us to screen a library of engineered variants. Using consensus design, we generated several improved variants that exhibit over 10-fold greater whole-cell activity than wild-type (WT) MHETase. This is revealed to be largely due to increased soluble expression, which biochemical and structural analysis indicates is due to improved protein folding.


Assuntos
Burkholderiales , Burkholderiales/enzimologia , Burkholderiales/genética , Burkholderiales/metabolismo , Ácidos Ftálicos/metabolismo , Ácidos Ftálicos/química , Hidrolases/metabolismo , Hidrolases/genética , Hidrolases/química , Solubilidade , Polietilenotereftalatos/metabolismo , Polietilenotereftalatos/química , Proteínas Recombinantes/metabolismo , Proteínas Recombinantes/genética , Proteínas Recombinantes/química , Engenharia de Proteínas/métodos , Dobramento de Proteína , Escherichia coli/genética , Escherichia coli/metabolismo , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/química , Modelos Moleculares
13.
Molecules ; 29(12)2024 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-38930935

RESUMO

Antimony (Sb) contamination poses significant environmental and health concerns due to its toxic nature and widespread presence, largely from anthropogenic activities. This study addresses the urgent need for an accurate speciation analysis of Sb, particularly in water sources, emphasizing its migration from polyethylene terephthalate (PET) plastic materials. Current methodologies primarily focus on total Sb content, leaving a critical knowledge gap for its speciation. Here, we present a novel analytical approach utilizing frontal chromatography coupled with inductively coupled plasma mass spectrometry (FC-ICP-MS) for the rapid speciation analysis of Sb(III) and Sb(V) in water. Systematic optimization of the FC-ICP-MS method was achieved through multivariate data analysis, resulting in a remarkably short analysis time of 150 s with a limit of detection below 1 ng kg-1. The optimized method was then applied to characterize PET leaching, revealing a marked effect of the plastic aging and manufacturing process not only on the total amount of Sb released but also on the nature of leached Sb species. This evidence demonstrates the effectiveness of the FC-ICP-MS approach in addressing such an environmental concern, benchmarking a new standard for Sb speciation analysis in consideration of its simplicity, cost effectiveness, greenness, and broad applicability in environmental and health monitoring.


Assuntos
Antimônio , Espectrometria de Massas , Polietilenotereftalatos , Antimônio/análise , Antimônio/química , Polietilenotereftalatos/química , Espectrometria de Massas/métodos , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/química , Monitoramento Ambiental/métodos
14.
Sci Rep ; 14(1): 11089, 2024 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-38750101

RESUMO

This investigation explored the presence of microplastics (MPs) and artificial cellulosic particles (ACPs) in commercial water marketed in single use 1.5 L poly(ethylene terephthalate) bottles. In this work we determined a mass concentration of 1.61 (1.10-2.88) µg/L and 1.04 (0.43-1.82) µg/L for MPs and ACPs respectively in five top-selling brands from the Spanish bottled water market. Most MPs consisted of white and transparent polyester and polyethylene particles, while most ACPs were cellulosic fibers likely originating from textiles. The median size of MPs and ACPs was 93 µm (interquartile range 76-130 µm) and 77 µm (interquartile range 60-96 µm), respectively. Particle mass size distributions were fitted to a logistic function, enabling comparisons with other studies. The estimated daily intake of MPs due to the consumption of bottled water falls within the 4-18 ng kg-1 day-1 range, meaning that exposure to plastics through bottled water probably represents a negligible risk to human health. However, it's worth noting that the concentration of plastic found was much higher than that recorded for tap water, which supports the argument in favour of municipal drinking water.


Assuntos
Água Potável , Microplásticos , Poluentes Químicos da Água , Microplásticos/análise , Água Potável/química , Água Potável/análise , Espanha , Poluentes Químicos da Água/análise , Celulose/química , Celulose/análise , Humanos , Tamanho da Partícula , Polietilenotereftalatos/química , Polietilenotereftalatos/análise
15.
Protein Sci ; 33(6): e4997, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38723110

RESUMO

Rieske oxygenases (ROs) are a diverse metalloenzyme class with growing potential in bioconversion and synthetic applications. We postulated that ROs are nonetheless underutilized because they are unstable. Terephthalate dioxygenase (TPADO PDB ID 7Q05) is a structurally characterized heterohexameric α3ß3 RO that, with its cognate reductase (TPARED), catalyzes the first intracellular step of bacterial polyethylene terephthalate plastic bioconversion. Here, we showed that the heterologously expressed TPADO/TPARED system exhibits only ~300 total turnovers at its optimal pH and temperature. We investigated the thermal stability of the system and the unfolding pathway of TPADO through a combination of biochemical and biophysical approaches. The system's activity is thermally limited by a melting temperature (Tm) of 39.9°C for the monomeric TPARED, while the independent Tm of TPADO is 50.8°C. Differential scanning calorimetry revealed a two-step thermal decomposition pathway for TPADO with Tm values of 47.6 and 58.0°C (ΔH = 210 and 509 kcal mol-1, respectively) for each step. Temperature-dependent small-angle x-ray scattering and dynamic light scattering both detected heat-induced dissociation of TPADO subunits at 53.8°C, followed by higher-temperature loss of tertiary structure that coincided with protein aggregation. The computed enthalpies of dissociation for the monomer interfaces were most congruent with a decomposition pathway initiated by ß-ß interface dissociation, a pattern predicted to be widespread in ROs. As a strategy for enhancing TPADO stability, we propose prioritizing the re-engineering of the ß subunit interfaces, with subsequent targeted improvements of the subunits.


Assuntos
Estabilidade Enzimática , Oxirredutases/química , Oxirredutases/metabolismo , Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/genética , Modelos Moleculares , Dioxigenases/química , Dioxigenases/metabolismo , Dioxigenases/genética , Temperatura , Escherichia coli/enzimologia , Escherichia coli/genética , Escherichia coli/metabolismo , Polietilenotereftalatos/química , Polietilenotereftalatos/metabolismo , Concentração de Íons de Hidrogênio , Complexo III da Cadeia de Transporte de Elétrons
16.
Part Fibre Toxicol ; 21(1): 26, 2024 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-38778339

RESUMO

BACKGROUND: During inhalation, airborne particles such as particulate matter ≤ 2.5 µm (PM2.5), can deposit and accumulate on the alveolar epithelial tissue. In vivo studies have shown that fractions of PM2.5 can cross the alveolar epithelium to blood circulation, reaching secondary organs beyond the lungs. However, approaches to quantify the translocation of particles across the alveolar epithelium in vivo and in vitro are still not well established. In this study, methods to assess the translocation of standard diesel exhaust particles (DEPs) across permeable polyethylene terephthalate (PET) inserts at 0.4, 1, and 3 µm pore sizes were first optimized with transmission electron microscopy (TEM), ultraviolet-visible spectroscopy (UV-VIS), and lock-in thermography (LIT), which were then applied to study the translocation of DEPs across human alveolar epithelial type II (A549) cells. A549 cells that grew on the membrane (pore size: 3 µm) in inserts were exposed to DEPs at different concentrations from 0 to 80 µg.mL- 1 ( 0 to 44 µg.cm- 2) for 24 h. After exposure, the basal fraction was collected and then analyzed by combining qualitative (TEM) and quantitative (UV-VIS and LIT) techniques to assess the translocated fraction of the DEPs across the alveolar epithelium in vitro. RESULTS: We could detect the translocated fraction of DEPs across the PET membranes with 3 µm pore sizes and without cells by TEM analysis, and determine the percentage of translocation at approximatively 37% by UV-VIS (LOD: 1.92 µg.mL- 1) and 75% by LIT (LOD: 0.20 µg.cm- 2). In the presence of cells, the percentage of DEPs translocation across the alveolar tissue was determined around 1% at 20 and 40 µg.mL- 1 (11 and 22 µg.cm- 2), and no particles were detected at higher and lower concentrations. Interestingly, simultaneous exposure of A549 cells to DEPs and EDTA can increase the translocation of DEPs in the basal fraction. CONCLUSION: We propose a combination of analytical techniques to assess the translocation of DEPs across lung tissues. Our results reveal a low percentage of translocation of DEPs across alveolar epithelial tissue in vitro and they correspond to in vivo findings. The combination approach can be applied to any traffic-generated particles, thus enabling us to understand their involvement in public health.


Assuntos
Material Particulado , Alvéolos Pulmonares , Emissões de Veículos , Humanos , Emissões de Veículos/toxicidade , Emissões de Veículos/análise , Células A549 , Material Particulado/toxicidade , Material Particulado/análise , Alvéolos Pulmonares/efeitos dos fármacos , Alvéolos Pulmonares/metabolismo , Tamanho da Partícula , Microscopia Eletrônica de Transmissão , Polietilenotereftalatos/química , Polietilenotereftalatos/toxicidade , Células Epiteliais Alveolares/efeitos dos fármacos , Células Epiteliais Alveolares/metabolismo , Poluentes Atmosféricos/toxicidade , Poluentes Atmosféricos/análise
17.
Environ Res ; 255: 119144, 2024 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-38751006

RESUMO

Currently, plastic waste and antibiotic wastewater are two of the most critical environmental problems, calling for urgent measures to take. A waste-to-wealth strategy for the conversion of polyethylene terephthalate (PET) plastic bottles into value-added materials such as carbon composite is highly recommended to clean wastewater contaminated by antibiotics. Inspired by this idea, we develop a novel PET-AC-ZFO composite by incorporating PET plastic-derived KOH-activated carbon (AC) with ZnFe2O4 (ZFO) particles for adsorptive removal of tetracycline (TTC). PET-derived carbon (PET-C), KOH-activated PET-derived carbon (PET-AC), and PET-AC-ZFO were characterized using physicochemical analyses. Central composite design (CCD) was used to obtain a quadratic model by TTC concentration (K), adsorbent dosage (L), and pH (M). PET-AC-ZFO possessed micropores (d ≈ 2 nm) and exceptionally high surface area of 1110 m2 g-1. Nearly 90% TTC could be removed by PET-AC-ZFO composite. Bangham kinetic and Langmuir isotherm were two most fitted models. Theoretical maximum TTC adsorption capacity was 45.1 mg g-1. This study suggested the role of hydrogen bonds, pore-filling interactions, and π-π interactions as the main interactions of the adsorption process. Thus, a strategy for conversion of PET bottles into PET-AC-ZFO can contribute to both plastic recycling and antibiotic wastewater mitigation.


Assuntos
Antibacterianos , Carbono , Tetraciclina , Poluentes Químicos da Água , Adsorção , Poluentes Químicos da Água/química , Poluentes Químicos da Água/análise , Tetraciclina/química , Antibacterianos/química , Carbono/química , Plásticos/química , Purificação da Água/métodos , Águas Residuárias/química , Polietilenotereftalatos/química
18.
Protein Eng Des Sel ; 372024 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-38713696

RESUMO

Plastic degrading enzymes have immense potential for use in industrial applications. Protein engineering efforts over the last decade have resulted in considerable enhancement of many properties of these enzymes. Directed evolution, a protein engineering approach that mimics the natural process of evolution in a laboratory, has been particularly useful in overcoming some of the challenges of structure-based protein engineering. For example, directed evolution has been used to improve the catalytic activity and thermostability of polyethylene terephthalate (PET)-degrading enzymes, although its use for the improvement of other desirable properties, such as solvent tolerance, has been less studied. In this review, we aim to identify some of the knowledge gaps and current challenges, and highlight recent studies related to the directed evolution of plastic-degrading enzymes.


Assuntos
Evolução Molecular Direcionada , Engenharia de Proteínas , Evolução Molecular Direcionada/métodos , Plásticos/química , Plásticos/metabolismo , Polietilenotereftalatos/química , Polietilenotereftalatos/metabolismo , Enzimas/genética , Enzimas/química , Enzimas/metabolismo
19.
Environ Pollut ; 351: 124106, 2024 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-38705445

RESUMO

Polyethylene terephthalate is a widely produced plastic polymer that exhibits considerable biodegradation resistance, making its derived microplastics ubiquitous environmental pollutants. In this study, a new yeast strain (Vanrija sp. SlgEBL5) was isolated and found to have lipase and esterase-positive capabilities for degrading polyethylene terephthalate microplastics. This isolate changed the microplastic surface charge from -19.3 to +31.0 mV and reduced more than 150 µm of its size in addition to reducing the intensity of the terephthalate, methylene, and ester bond functional groups of the polymer in 30 days. Tween 20 as a chemical auxiliary treatment combined with biodegradation increased the microplastic degradation rate from 10 to 16.6% and the thermal degradation rate from 85 to 89%. Releasing less potentially hazardous by-products like 1,2 diethyl-benzene despite the higher abundance of long-chain n-alkanes, including octadecane and tetracosane was also the result of the bio + chemical treatment. Altogether, the findings showed that Vanrija sp. SlgEBL5 has the potential as a biological treating agent for polyethylene terephthalate microplastics, and the simultaneous bio + chemical treatment enhanced the biodegradation rate and efficiency.


Assuntos
Biodegradação Ambiental , Microplásticos , Polietilenotereftalatos , Polissorbatos , Polietilenotereftalatos/metabolismo , Polietilenotereftalatos/química , Microplásticos/metabolismo , Polissorbatos/química , Leveduras/metabolismo
20.
Waste Manag ; 183: 260-270, 2024 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-38776828

RESUMO

The landfill is one of the most important sources of microplastics (MPs). The pretreatment method is a precondition of microplastics study for the presence of complex substances in landfills. Therefore, it is essential to examine the impact of different pretreatment methods on the microplastics detection. A literature review and a comparison experiment on digestion solutions were performed to establish a comprehensive identification method for MPs in landfills. When exposed to of 30 % H2O2, minimal mass reduction of PE, PP and PET were 4.00 %, 3.00 % and 3.00 % respectively, and the least surface damage was observed in MPs, while exhibiting the most optimal peak value for infrared spectral characteristics. It is demonstrated that the effect of 30 % H2O2 dissolution was superior compared to 10 % KOH and 65 % HNO3. The method was subsequently utilized to investigate the distribution of MPs in a landfill. The dominant MPs were polyethylene (PE, 18.56-23.91 %), polyethylene terephthalate (PET, 8.80-18.66 %), polystyrene (PS, 10.31-18.09 %), and polypropylene (PP, 11.60-14.91 %). The comprehensive identification method of "NaCl density separation + 30 % H2O2 digestion + NaI density separation + sampling microscope + Mirco-FTIR" is suitable for the detection of MPs in landfills.


Assuntos
Resíduos Sólidos , Instalações de Eliminação de Resíduos , Eliminação de Resíduos/métodos , Polietileno/análise , Polietilenotereftalatos/análise , Poliestirenos/análise , Polipropilenos/análise
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