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Fish are excellent bioindicators and can reveal the presence of plastic in the environment. Diagnosing the composition and abundance of polymers in the fish diet makes it possible to evaluate their point sources and possible trophic transfers. We aimed to use the gastrointestinal contents of Poecilia reticulata in subtropical urban streams to detect the occurrence, shape, color, size, and chemical composition of polymers. For this, the diet of 240 individuals was analyzed using the volumetric method, and the microplastics (MPs; < 5 mm) recorded were characterized using Raman spectroscopy. Individuals predominantly consumed organic detritus and aquatic macroinvertebrates, with higher proportions of Diptera. A total of 111 plastic particles (< 0.5 to 12 mm) were recorded, and a subset of 14.4% was subjected to a micro-Raman spectrometer (830 nm excitation). The occurrence of polyethylene terephthalate (PET) and polypropylene (PP) with phthalocyanine dye was recorded. Some fragments could not be identified by Raman, but they contained indigo blue dye. Poecilia reticulata had a predominantly detritivorous diet with a record of plastic consumption, reflecting environmental pollution. Our results demonstrate that individuals of P. reticulata have ingested MPs in urban streams. This reinforces the need for future studies on the relationship between the presence of MPs in fish and the level of pollution in streams, comparisons with species of different feeding habits, and the potentially harmful effects on the entire biota.

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New composites produced with recycled waste are needed to manufacture more sustainable construction materials. This paper aimed to analyze the hygrothermal and mechanical performance of plasterboard with a polymethylhydrosiloxane (PMHS) content, incorporating recycled PET microplastic waste and varying factors such as PMHS dose, homogenization time, and drying temperature after setting. A cube-centered experimental design matrix was performed. The crystal morphology, porosity, fluidity, water absorption, flexural strength, and thermal conductivity of plasterboards were measured. The results showed that incorporating recycled PET microplastics does not produce a significant difference in the absorption and flexural strength of plasterboards. However, the addition of recycled PET reduced the thermal conductivity of plasterboards by around 10%.

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The study aimed to obtain environmentally relevant microfibers (MFs) from polyester fabric and assess their impact on the oyster Crassostrea gasar. MFs were obtained by grinding the fabric, and their accumulation in oysters gills and digestive glands was analyzed after exposure to 0.5 mg/L for 2 and 24 h. Additionally, a 48 h depuration was conducted on the oysters exposed for 24 h. Sublethal effects were assessed in oysters exposed for 24 h and depurated for 48 h, using biomarkers like Catalase (CAT), Glutathione S-transferase (GST), and Glutathione Peroxidase (GPx), along with histological analyses. Polyester fabric grinding produced significant MFs (average length: 570 µm) with degraded surface and increased malleability. Oysters showed increased MF accumulation in digestive glands post-exposure, with no impact on antioxidant enzymes. Depuration decreased MFs accumulation. Histological analysis revealed accumulation in the stomach and brown cells, possibly indicating inflammation. This raises concerns about MFs bioaccumulation in marine organisms, impacting the food chain and safety.

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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 disposal of plastics and metal-derived compounds results in the contamination of the environment with nano/microparticles, leading to the exposure of various organisms to these harmful particles. However, the impacts of these particles on pollinating insects, which provide relevant ecosystem services, are not well understood. The aim of this study was to assess the effects of microscopic particles on the tropical pollinator Partamona helleri (Apinae: Meliponini), specifically evaluating the toxicity of plastic microparticles (polystyrene - PS, and polyethylene terephthalate - PET) and nanoparticles of a metal oxide (titanium dioxide - TiO2) via larval ingestion by bees reared in vitro. The survival rate of P. helleri larvae was not affected by the ingestion of particles of PS (500 ng/bee), PET (500 ng/bee), or TiO2 (10 µg/bee) compared to the non-treated diet (control or diet without the particles). Adults derived from treated larvae had increased body weight compared to the control, and the walking behavior of adults was altered by the ingestion of particles. Adults that ingested PET or TiO2 as larvae tended to rest for a longer time and interact more with other bees than the control. Hemocyte counts also changed, with a shift in the proportion of plasmatocytes and prohemocytes in treated individuals. Our findings suggest that even levels considered low for honey bees of exposure to plastic microparticles or metal nanoparticles can harm the health and behavior of stingless bees.

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Extensive plastic production has become a serious environmental and health problem due to the lack of efficient treatment of plastic waste. Polyethylene terephthalate (PET) is one of the most used polymers and is accumulating in landfills or elsewhere in nature at alarming rates. In recent years, enzymatic degradation of PET by Ideonella sakaiensis PETase (IsPETase), a cutinase-like enzyme, has emerged as a promising strategy to completely depolymerize this polymer into its building blocks. Here, inspired by the architecture of cutinases and lipases homologous to IsPETase and using 3D structure information of the enzyme, we rationally designed three mutations in IsPETase active site for enhancing its PET-degrading activity. In particular, the S238Y mutant, located nearby the catalytic triad, showed a degradation activity increased by 3.3-fold in comparison to the wild-type enzyme. Importantly, this structural modification favoured the function of the enzyme in breaking down highly crystallized (~31%) PET, which is found in commercial soft drink bottles. In addition, microscopical analysis of enzyme-treated PET samples showed that IsPETase acts better when the smooth surface of highly crystalline PET is altered by mechanical stress. These results represent important progress in the accomplishment of a sustainable and complete degradation of PET pollution.

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BACKGROUND: Occlusal splints can protect teeth during bruxism, preventing tooth wear, as well as during sports activities, shielding them from impacts. OBJECTIVES: To verify the influence of thermal cycles and disinfection on the roughness, microhardness and color of polyethylene terephthalate glycol/thermoplastic polyurethane (PETG/TPU) and poly(methyl methacrylate) (PMMA). MATERIAL AND METHODS: Thirty-six PETG/TPU samples and 36 PMMA samples were prepared (ø10 mm × 3 mm). Six groups were created according to the material and the disinfection method used (n = 12 each): PETG/TPU (glister), PETG/TPU (hypochlorite), PETG/TPU (soap), PMMA (glister), PMMA (hypochlorite), and PMMA (soap). Roughness, Knoop microhardness and color evaluations were performed before the experiments (T1), after thermocycling (T2) and after disinfection (T3). Three-way repeated measures analysis of variance (ANOVA) and Tukey's test were used for statistical evaluations. RESULTS: For roughness and color, ANOVA showed statistical significance based on the interaction between thermal cycling, material and disinfectant factors. In terms of Knoop microhardness, ANOVA showed statistical significance based on the interaction between thermal cycling and material factors. CONCLUSIONS: Roughness results were clinically acceptable in all groups at all time points, except the PETG/TPU and PMMA groups disinfected with hypochlorite. Microhardness significantly increased for both materials after thermal cycling, and at all time points, the microhardness of PMMA was significantly higher than that of PETG/TPU. After thermal cycling, the color changes were clinically unacceptable in all groups.

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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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Hot springs are extreme environments in which well-adapted microorganisms with biotechnological applications can thrive naturally. These thermal environments across Peruvian territory have, until now, remained poorly investigated. In this study, two hot springs, El Tragadero and Quilcate, located in Cajamarca (Peru) were selected in order to investigate the biotechnological potential of indigenous thermophilic bacteria. Enrichment and isolation processes were carried out using microbial mats, sediments, biofilms, and plastic polymers as samples. Screening for biosurfactants and siderophores production, as well as for polyethylene terephthalate (PET) hydrolysis was done using culture-dependent techniques. After molecular identification, Bacillus was found as the most abundant genus in both hot springs. Bacillus velezensis was found producing biosurfactants under high-level temperature. Anoxybacillus species (A. salavatliensis and A. gonensis) are here reported as siderophore-producing bacteria for the first time. Additionally, Brevibacillus and the less-known bacterium Tistrella mobilis were found demonstrating PET hydrolysis activity. Our study provides the first report of thermophilic bacteria isolated from Peruvian hot springs with biotechnological potential for the bioremediation of oil-, metal- and plastic-polluted environments.