Sulfur-Rich Norbornadiene-Derived Infrared Transparent Polymers by Inverse Vulcanization.

Infrared (IR) transparent polymer materials prepared by inverse vulcanization, as a promising candidate to replace inorganic materials, are new materials for constructing key devices in IR optics. However, it is difficult to achieve a balance between infrared optical and thermal properties in polymers due to the intrinsic infrared absorption of organic materials. Herein, our strategy is to construct a high boiling point symmetrical molecular norbornadiene derivative cross-linking agent (DMMD) which can be inverse vulcanized with molten sulfur, and obtain Poly(S-r-DMMD) with different sulfur content by controlling the feed ratio of sulfur. With the rigid core and low IR activity in DMMD, the prepared polymers exhibit tunable thermal properties (Tg: 98.3-119.8 °C) and high IR transmittance (medium-wave infrared region (MWIR): 42.9-52.6 %; long-wave infrared region (LWIR): 1.5-5.29 %). In addition, Poly(S-r-DMMD) can be used to prepare large-size free-standing Fresnel lenses for IR imaging by simple hot-pressing, which provides flexibility in the design and production of IR fine lenses. This study provides a novel strategy for balancing the thermal and optical properties of IR transparent polymer materials, while providing relevant references for balancing the IR optical and thermal properties of polymer materials.

Advanced applications in enzyme-induced electrospun nanofibers.

Electrospun nanofibers, renowned for their high specific surface area, robust mechanical properties, and versatile chemical functionalities, offer a promising platform for enzyme immobilization. Over the past decade, significant strides have been made in developing enzyme-induced electrospun nanofibers (EIEN). This review systematically summarizes the advanced applications of EIEN which are fabricated using both non-specific immobilization methods including interfacial adsorption (direct adsorption, cross-linking, and covalent binding) and encapsulation, and specific immobilization techniques (coordination and affinity immobilization). Future research should prioritize optimizing immobilization techniques to achieve a balance between enzyme activity, stability, and cost-effectiveness, thereby facilitating the industrialization of EIEN. We elucidate the rationale behind various immobilization methods and their applications, such as wastewater treatment, biosensors, and biomedicine. We aim to provide guidelines for developing suitable EIEN immobilization techniques tailored to specific future applications.

The effect of low-temperature plasma pretreatment on the biodegradability of polyethylene films.

With the increasing focus on environmental friendliness and sustainable development, extensive research has been conducted on the biodegradation of plastics. The non-hydrolyzable, highly hydrophobic, and high-molecular-weight properties of polyethylene (PE) pose challenges for cell interaction and biodegradation of PE substrates. To overcome these obstacles, PE films were treated with low-temperature plasma before biodegradation. The morphology, surface chemistry, molecular weight, and weight loss of PE films after plasma treatment and biodegradation were studied. The plasma treatment decreased the surface water contact angle, formed C-O and C = O groups, and decreased the molecular weight of PE films. With the increased pretreatment time, the biodegradation efficiency rose to 2.6% from 0.63% after 20 days of incubation. The mechanism was proposed that the surface oxygen-containing groups formed by plasma treatment can facilitate the bio-accessibility and be further decomposed and utilised by the microbes. This study provided an effective and rapid pretreatment strategy for improving biodegradation of PE.

Screening of polyurethane-degrading microbes using a quenching fluorescence probe by microfluidic droplet sorting.

Excessive use of polyurethane (PU) polymers has led contributed to serious environmental pollution. The plastic recycling technology using microorganisms and enzymes as catalysts offers a promising green and low-carbon approach for managing plastic waste. However, current methods for screening PU-degrading strains suffer from drawbacks such as being time-consuming and inefficient. Herein, we present a novel approach for screening PU-degrading microorganisms using a quenching fluorescent probe along with the fluorescence-activated droplet sorting (FADS). The FPAP could specifically recognize the 4,4'-methylenedianiline (MDA) derivates released from PU degradation, with fluorescence quenching as a response. Based on the approach, we successfully screen two PU-degrading strains (Burkholderia sp. W38 and Bacillus sp. C1). After 20 d of cultivation, strain W38 and C1 could degrade 41.58% and 31.45% of polyester-PU film, respectively. Additionally, three metabolites were identified during the degradation of PU monomer (2,4-toluene diamine, 2,4-TDA) and a proposed degradation pathway was established. Consequently, the fluorescence probe integrated with microfluidic droplet systems, demonstrates potential for the development of innovative PU-biocatalysts. Furthermore, the identification of the 2,4-TDA degradation pathway provides valuable insights that can propel advancements in the field of PU biodegradation.

Microbial biofilms as a platform for diverse biocatalytic applications.

Microbial biofilms have gained significant traction in commercial wastewater treatment due to their inherent resilience, well-organized structure, and potential for collaborative metabolic processes. As our understanding of their physiology deepens, these living catalysts are finding exciting applications beyond wastewater treatment, including the production of bulk and fine chemicals, bioelectricity generation, and enzyme immobilization. While the biological applications of biofilms in different biocatalytic systems have been extensively summarized, the applications of artificially engineered biofilms were rarely discussed. This review aims to bridge this gap by highlighting the untapped potential of engineered microbial biofilms in diverse biocatalytic applications, with a focus on strategies for biofilms engineering. Strategies for engineering biofilm-based systems will be explored, including genetic modification, synthetic biology approaches, and targeted manipulation of biofilm formation processes. Finally, the review will address key challenges and future directions in developing robust biofilm-based biocatalytic platforms for large-scale production of chemicals, pharmaceuticals, and biofuels.

BhrPETase catalyzed polyethylene terephthalate depolymerization: A quantum mechanics/molecular mechanics approach.

Polyethylene terephthalate (PET) is a widely used material in our daily life, particularly in areas such as packaging, fibers, and engineering plastics. However, PET waste can accumulate in the environment and pose a great threat to our ecosystem. Recently enzymatic conversion has emerged as an efficient and green strategy to address the PET crisis. Here, using a theoretical approach combining molecular dynamics simulation and quantum mechanics/molecular mechanics calculations, the depolymerization mechanism of the thermophilic cutinase BhrPETase was fully deciphered. Surprisingly, unlike the previously studied cutinase LCCICCG, our results indicate that the first step, catalytic triad assisted nucleophilic attack, is the rate-determining step. The corresponding Boltzmann weighted average energy barrier is 18.2 kcal/mol. Through extensive comparison between BhrPETase and LCCICCG, we evidence that key features like charge CHis@N1 and angle APET@C1-Ser@O1-His@H1 significantly impact the depolymerization efficiency of BhrPETase. Non-covalent bond interaction and distortion/interaction analysis inform new insights on enzyme engineer and may aid the recycling of enzymatic PET waste. This study will aid the advancement of the plastic bio-recycling economy and promote resource conservation and reuse.

Tandem Integration of Biological and Electrochemical Catalysis for Efficient Polyester Upcycling under Ambient Conditions.

Excessive production of waste polyethylene terephthalate (PET) poses an ecological challenge, which necessitates developing technologies to extract the values from end-of-life PET. Upcycling has proven effective in addressing the low profitability of current recycling strategies, yet existing upcycling technologies operate under energy-intensive conditions. Here we report a cascade strategy to steer the transformation of PET waste into glycolate in an overall yield of 92.6% under ambient conditions. The cascade approach involves setting up a robust hydrolase with 95.6% PET depolymerization into ethylene glycol (EG) monomer within 12 h, followed by an electrochemical process initiated by a CO-tolerant Pd/Ni(OH)2 catalyst to convert the EG intermediate into glycolate with high Faradaic efficiency of 97.5%. Techno-economic analysis and life cycle assessment indicate that, compared with the widely adopted electrochemical technology that heavily relies on alkaline pretreatment for PET depolymerization, our designed enzymatic-electrochemical approach offers a cost-effective and low-carbon pathway to upgrade PET.

Regioselective enzymatic depolymerization of aromatic-aliphatic polyester revealed by computational modelling.

Poly(butylene adipate-co-terephthalate) (PBAT) is widely utilized in the production of food packaging and mulch films. Its extensive application has contributed significantly to global solid waste, posing numerous environmental challenges. Recently, enzymatic recycling has emerged as a promising eco-friendly solution for the management of plastic waste. Here, we systematically investigate the depolymerization mechanism of PBAT catalyzed by cutinase TfCutSI with molecular docking, molecular dynamics simulations, and quantum mechanics/molecular mechanics calculations. Although the binding affinities for acid ester and terephthalic acid ester bonds are similar, a regioselective depolymerization mechanism and a "chain-length" effect on regioselectivity were proposed and evidenced. The regioselectivity is highly associated with specific structural parameters, namely Substrate@O4-Met@H7 and Substrate@C1-Ser@O1 distances. Notably, the binding mode of BTa captured by X-ray crystallography does not facilitate subsequent depolymerization. Instead, a previously unanticipated binding mode, predicted through computational analysis, is confirmed to play a crucial role in BTa depolymerization. This finding proves the critical role of computational modelling in refining experimental results. Furthermore, our results revealed that both the hydrogen bond network and enzyme's intrinsic electric field are instrumental in the formation of the final product. In summary, these novel molecular insights into the PBAT depolymerization mechanism offer a fundamental basis for enzyme engineering to enhance industrial plastic recycling.

Optimization Design of Fluoro-Cyanogen Copolymer Electrolyte to Achieve 4.7 V High-Voltage Solid Lithium Metal Battery.

Raising the charging voltage and employing high-capacity cathodes like lithium cobalt oxide (LCO) are efficient strategies to expand battery capacity. High voltage, however, will reveal major issues such as the electrolyte's low interface stability and weak electrochemical stability. Designing high-performance solid electrolytes from the standpoint of substance genetic engineering design is consequently vital. In this instance, stable SEI and CEI interface layers are constructed, and a 4.7 V high-voltage solid copolymer electrolyte (PAFP) with a fluoro-cyanogen group is generated by polymer molecular engineering. As a result, PAFP has an exceptionally broad electrochemical window (5.5 V), a high Li+ transference number (0.71), and an ultrahigh ionic conductivity (1.2 mS cm-2) at 25 °C. Furthermore, the Li||Li symmetric cell possesses excellent interface stability and 2000 stable cycles at 1 mA cm-2. The LCO|PAFP|Li batteries have a 73.7% retention capacity after 1200 cycles. Moreover, it still has excellent cycling stability at a high charging voltage of 4.7 V. These characteristics above also allow PAFP to run stably at high loading, showing excellent electrochemical stability. Furthermore, the proposed PAFP provides new insights into high-voltage resistant solid polymer electrolytes.

Novel polyurethane-degrading cutinase BaCut1 from Blastobotrys sp. G-9 with potential role in plastic bio-recycling.

Environmental pollution caused by plastic waste has become global problem that needs to be considered urgently. In the pursuit of a circular plastic economy, biodegradation provides an attractive strategy for managing plastic wastes, whereas effective plastic-degrading microbes and enzymes are required. In this study, we report that Blastobotrys sp. G-9 isolated from discarded plastic in landfills is capable of depolymerizing polyurethanes (PU) and poly (butylene adipate-co-terephthalate) (PBAT). Strain G-9 degrades up to 60% of PU foam after 21 days of incubation at 28 â„ƒ by breaking down carbonyl groups via secretory hydrolase as confirmed by structural characterization of plastics and degradation products identification. Within the supernatant of strain G-9, we identify a novel cutinase BaCut1, belonging to the esterase family, that can reproduce the same effect. BaCut1 demonstrates efficient degradation toward commercial polyester plastics PU foam (0.5 mg enzyme/25 mg plastic) and agricultural film PBAT (0.5 mg enzyme/10 mg plastic) with 50% and 18% weight loss at 37 â„ƒ for 48 h, respectively. BaCut1 hydrolyzes PU into adipic acid as a major end-product with 42.9% recovery via ester bond cleavage, and visible biodegradation is also identified from PBAT, which is a beneficial feature for future recycling economy. Molecular docking, along with products distribution, elucidates a special substrate-binding modes of BaCut1 with plastic substrate analogue. BaCut1-mediated polyester plastic degradation offers an alternative approach for managing PU plastic wastes through possible bio-recycling.

Depolymerization of the polyester-polyurethane by amidase GatA250 and enhancing the production of 4,4'-methylenedianiline with cutinase LCC.

Polyurethane (PU) is a complex polymer synthesized from polyols and isocyanates. It contains urethane bonds that resist hydrolysis, which decreases the efficiency of biodegradation. In this study, we first expressed the amidase GatA250, and then, assessed the enzymatic characterization of GatA250 and its efficiency in degrading the polyester-PU. GatA250 degraded self-synthesized thermoplastic PU film and postconsumption foam with degradation efficiency of 8.17% and 4.29%, respectively. During the degradation, the film released 14.8 µm 4,4'-methylenedianiline (MDA), but 1,4-butanediol (BDO) and adipic acid (AA) were not released. Our findings indicated that GatA250 only cleaved urethane bonds in PU, and the degradation efficiency was extremely low. Hence, we introduced the cutinase LCC, which possesses hydrolytic activity on the ester bonds in PU, and then used both enzymes simultaneously to degrade the polyester-PU. The combined system (LCC-GatA250) had higher degradation efficiency for the degradation of PU film (42.2%) and foam (13.94%). The combined system also showed a 1.80 time increase in the production of the monomer MDA, and a 1.23 and 3.62 times increase in the production of AA and BDO, respectively, compared to their production recorded after treatment with only GatA250 or LCC. This study provides valuable insights into PU pollution control and also proposes applicable solutions to manage PU wastes through bio-recycling.

Identification and characterization of a fungal cutinase-like enzyme CpCut1 from Cladosporium sp. P7 for polyurethane degradation.

Plastic degradation by biological systems emerges as a prospective avenue for addressing the pressing global concern of plastic waste accumulation. The intricate chemical compositions and diverse structural facets inherent to polyurethanes (PU) substantially increase the complexity associated with PU waste management. Despite the extensive research endeavors spanning over decades, most known enzymes exhibit a propensity for hydrolyzing waterborne PU dispersion (i.e., the commercial Impranil DLN-SD), with only a limited capacity for the degradation of bulky PU materials. Here, we report a novel cutinase (CpCut1) derived from Cladosporium sp. P7, which demonstrates remarkable efficiency in the degrading of various polyester-PU materials. After 12-h incubation at 55°C, CpCut1 was capable of degrading 40.5% and 20.6% of thermoplastic PU film and post-consumer foam, respectively, while achieving complete depolymerization of Impranil DLN-SD. Further analysis of the degradation intermediates suggested that the activity of CpCut1 primarily targeted the ester bonds within the PU soft segments. The versatile performance of CpCut1 against a spectrum of polyester-PU materials positions it as a promising candidate for the bio-recycling of waste plastics.IMPORTANCEPolyurethane (PU) has a complex chemical composition that frequently incorporates a variety of additives, which poses significant obstacles to biodegradability and recyclability. Recent advances have unveiled microbial degradation and enzymatic depolymerization as promising waste PU disposal strategies. In this study, we identified a gene encoding a cutinase from the PU-degrading fungus Cladosporium sp. P7, which allowed the expression, purification, and characterization of the recombinant enzyme CpCut1. Furthermore, this study identified the products derived from the CpCut1 catalyzed PU degradation and proposed its underlying mechanism. These findings highlight the potential of this newly discovered fungal cutinase as a remarkably efficient tool in the degradation of PU materials.

Isolation and characterization of polyester polyurethane-degrading bacterium Bacillus sp. YXP1.

Microorganisms have the potential to be applied for the degradation or depolymerization of polyurethane (PU) and other plastic waste, which have attracted global attention. The appropriate strain or enzyme that can effectively degrade PU is the key to treat PU plastic wastes by biological methods. Here, a polyester PU-degrading bacterium Bacillus sp. YXP1 was isolated and identified from a plastic landfill. Three PU substrates with increasing structure complexities, including Impranil DLN, poly (1,4-butylene adipate)-based PU (PBA-PU), and polyester PU foam, were used to evaluate the degradation capacity of Bacillus sp. YXP1. Under optimal conditions, strain YXP1 could completely degrade 0.5% Impranil DLN within 7 days. After 30 days, the weight loss of polyester PU foam by strain YXP1 was as high as 42.1%. In addition, PBA-PU was applied for degradation pathway analysis due to its clear composition and chemical structure. Five degradation intermediates of PBA-PU were identified, including 4,4'-methylenedianiline (MDA), 1,4-butanediol, adipic acid, and two MDA derivates, indicating that strain YXP1 could depolymerize PBA-PU by the hydrolysis of ester and urethane bonds. Furthermore, the extracellular enzymes produced by strain YXP1 could hydrolyze PBA-PU to generate MDA. Together, this study provides a potential bacterium for the biological treatment of PU plastic wastes and for the mining of functional enzymes.

Simulated gastrointestinal digestion of two different sources of biodegradable microplastics and the influence on gut microbiota.

Biodegradable plastics, were considered environmentally friendly, may produce more microplastic particles (MPs) within the same period and exert more pronounced adverse effects on human health than traditional non-biodegradable plastics. Thus, this study investigated the changes of two kinds of biodegradable MPs from different sources in the digestive tract by using simulated digestion and fermentation models in vitro, with particle size, scanning electron microscopy (SEM) and gel permeation chromatography (GPC) analysis, and their implications on the gut microbiota were detected by full-length bacterial 16S rRNA gene amplicon sequencing. Poly(ε-caprolactone) (PCL) MPs exhibited stability in the upper gastrointestinal tract, while poly(lactic acid) (PLA) MPs were degraded beginning in the small intestine digestion phase. Both PCL and PLA MPs were degraded and oligomerized during colonic fermentation. Furthermore, this study highlighted the disturbance of the gut microbiota induced by MPs and their oligomers. PCL and PLA MPs significantly changed the composition and reduced the α-diversity of the gut microbiota. PCL and PLA MPs exhibited the same inhibitory effects on key probiotics such as Bifidobacterium, Lactobacillus, Faecalibacterium, Limosilactobacillus, Blautia, Romboutsia, and Ruminococcus, which highlighted the potential hazards of these materials for human health. In conclusion, this study illuminated the potential biodegradation of MPs through gastrointestinal digestion and the complex interplay between MPs and the gut microbiota. The degradable characteristic of biodegradable plastics may cause more MPs and greater harm to human health.

Lighting up Pyruvate Metabolism in Saccharomyces cerevisiae by a Genetically Encoded Fluorescent Biosensor.

Monitoring intracellular pyruvate is useful for the exploration of fundamental metabolism and for guiding the construction of yeast cell factories for chemical production. Here, we employed a genetically encoded fluorescent Pyronic biosensor to light up the pyruvate metabolic state in the cytoplasm, nucleus, and mitochondria of Saccharomyces cerevisiae BY4741. A strong correlation was observed between the pyruvate fluctuation in mitochondria and cytoplasm when exposed to different metabolites. Further metabolic analysis of pyruvate uptake and glycolytic dynamics showed that glucose and fructose dose-dependently activated cytoplasmic pyruvate levels more effectively than direct exposure to pyruvate. Meanwhile, the Pyronic biosensor could visually distinguish phenotypes of the wild-type S. cerevisiae BY4741 and the pyruvate-hyperproducing S. cerevisiae TAM at a single-cell resolution, having the potential for high-throughput screening. Overall, Pyronic biosensors targeting different suborganelles contribute to mapping and studying the central carbon metabolism in-depth and guide the design and construction of yeast cell factories.

Palmitoleic acid-rich oleaginous yeast Scheffersomyces segobiensis DSM 27193 exerts anti-obesity effects by ameliorating hepatic steatosis and adipose tissue hypertrophy.

BACKGROUND: Yeast biomass, encompassing fatty acids, terpenoids, vitamins, antioxidants, enzymes, and other bioactive compounds have been extensively utilized in food-related fields. The safety and potential bioactivities of Scheffersomyces segobiensis DSM 27193, an oleaginous yeast strain, are unclear. RESULTS: Scheffersomyces segobiensis DSM 27193 accumulated large palmitoleic acid (POA) levels (43.4 g kg-1 biomass) according to the results of whole-cell components. We annotated the Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, and predicted the categories and host of the pathogen-host interactions (PHI) genes in S. segobiensis DSM 27193. However, S. segobiensis DSM 27193 did not exert toxic effects in mice. Administration of S. segobiensis DSM 27193 led to substantial weight reduction by diminishing food intake in an obesity mouse model. Additionally, it reversed hepatic steatosis and adipose tissue hypertrophy, and improved abnormalities in serum biochemical profiles such as triglyceride, total cholesterol, low-density lipoprotein cholesterol, lipopolysaccharide, tumor necrosis factor-α, interleukin-1ß, and interleukin-6. CONCLUSION: This study is the first to illustrate the safety and effects of S. segobiensis DSM 27193 against obesity and offers a scientific rationale for its application in functional food supplements. © 2023 Society of Chemical Industry.

Enzymatic Upcycling of PET Waste to Calcium Terephthalate for Battery Anodes.

Biotechnological recycling offers a promising solution to address the environmental concerns associated with waste plastics, particularly polyethylene terephthalate (PET), widely utilized in packaging materials and textiles. To advance the development of a bio-based circular plastic economy, innovative upcycling strategies capable of generating higher-value products are needed. In this study, we enhanced the enzymatic depolymerization of waste PET by incorporating highly concentrated calcium ions (up to 1 m) to the hydrolytic reaction catalyzed by the best currently known enzyme LCCICCG . The presence of calcium ions not only improved the thermal stability and activity of the biocatalyst but also significantly reduced the consumption of base required to maintain optimal pH levels. Employing optimized conditions at 80 °C for 12 h, we successfully converted ≈84 % of the waste PET (200 g L-1 ) into solid hydrated calcium terephthalate (CaTP ⋅ 3H2 O) as the primary product instead of soluble terephthalate salt. CaTP ⋅ 3H2 O was easily purified and employed as a raw material for battery electrode production, exhibiting an initial reversible specific capacity of 164.2 mAh g-1 . Through techno-economic analysis, we conclusively demonstrated that the one-pot biocatalysis-based synthesis of CaTP is a superior PET upcycling strategy than the secondary synthesis method employing recycled terephthalic acid.

Engineering Scheffersomyces segobiensis for palmitoleic acid-rich lipid production.

Palmitoleic acid (POA; C16:1) is an essential high-value ω-7-conjugated fatty acid with beneficial bioactivities and potential applications in the nutraceutical and pharmaceutical industries. Previously, the oleaginous yeast Scheffersomyces segobiensis DSM27193 has been identified as a promising production host as an alternative for POA extraction from plant or animal sources. Here, the POA-producing capacity of this host was further expanded by optimizing the fermentation process and molecular strain engineering. Specifically, a dual fermentation strategy (O-S dynamic regulation strategy) focused on the substrate and dissolved oxygen concentration was designed to eliminate ethanol and pyruvate accumulation during fermentation. Key genes influencing POA production, such as jen, dgat, ole were identified on the transcriptional level and were subsequently over-expressed. Furthermore, the phosphoketolase (Xpk)/phosphotransacetylase (Pta) pathway was introduced to improve the yield of the precursor acetyl-CoA from glucose. The resulting cell factory SS-12 produced 7.3 g/L of POA, corresponding to an 11-fold increase compared to the wild type, presenting the highest POA titre reported using oleaginous yeast to date. An economic evaluation based on the raw materials, utilities and facility-dependent costs showed that microbial POA production using S. segobiensis can supersede the current extraction method from plant oil and marine fish. This study reports the construction of a promising cell factory and an effective microbial fermentation strategy for commercial POA production.

Maximizing the benefits of biofilms in fermentation processes.

Biofilm-based fermentation has great potential, as it possesses inherent characteristics such as self-immobilization, high resistance to reactants, and long-term activity. This forum focuses on research targets for promoting biofilm engineering to maximize the beneficial features of biofilms and to effectively utilize them in biofilm-mediated fermentation.