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Nafion membranes are widely used as proton exchange membranes, but their proton conductivity deteriorates in high-temperature environments due to the loss of water molecules. To address this challenge, we propose the utilization of porous aromatic frameworks (PAFs) as a potential solution. PAFs exhibit remarkable characteristics, such as a high specific surface area and porosity, and their porous channels can be post-synthesized. Here, a novel approach was employed to synthesize a PAF material, designated as PAF-45D, which exhibits a specific surface area of 1571.9 m2·g-1 and possesses the added benefits of facile synthesis and a low cost. Subsequently, sulfonation treatment was applied to PAF-45D in order to introduce sulfonic acid groups into its pores, resulting in the formation of PAF-45DS. The successful incorporation of sulfonic groups was confirmed through TG, IR, and EDS analyses. Furthermore, a novel Nafion composite membrane was prepared by incorporating PAF-45DS. The Nyquist plot of the composite membranes demonstrates that the sulfonated PAF-45DS material can enhance the proton conductivity of Nafion membranes at high temperatures. Specifically, under identical film formation conditions, doping with a 4% mass fraction of PAF-45DS, the conductivity of the Nafion composite membrane increased remarkably from 2.25 × 10-3 S·cm-1 to 5.67 × 10-3 S·cm-1, nearly 2.5 times higher. Such promising and cost-effective materials could be envisioned for application in the field of Nafion composite membranes.
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Utilizing the ubiquitous fog in nature to create decentralized energy-harvesting devices, free from geographical and hydrological constraints, presents an opportunity to foster sustainable power generation. Extracting electrical energy from fog relies heavily on fog-digesting performance. Improving the efficiency of fogwater utilization remains a formidable challenge for existing fogwater energy-harvesting technologies. Inspired by the water-harvesting behavior of Tillandsia leaves, a smart lanceolate surface is developed to harvest triboelectric energy by rapidly digesting fog. Such a surface exhibits capabilities in fog management, encompassing precise fog capture, transportation, and critical droplet separation. Specifically, fog droplets condense at hydrophilic sites of acylated cellulose ester, subsequently migrating toward the rear under Laplace pressure, thereby producing energy as they traverse through the tail end. Such architecture yields a brief voltage restoration period (with an average of 9.36 s), can rush the capacitor to 11.59 V within 20 s, and achieves a water-digestion rate of up to 71.05 kg/m2 h. This biomimetic approach enhances the water-digestion efficacy of the atmospheric water energy apparatus and offers perspectives on mitigating deficiencies in power resources.
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In this study, we explore the mass transfer and separation mechanism of Li+ and Mg2+ confined within the flexible nanoporous zeolite imidazolate framework ZIF-8 under the influence of an electric field, employing molecular dynamics simulation. Our results highlight that the electric field accelerates the dehydration process of ions and underscore the critical importance of ZIF-8 framework flexibility in determining the separation selectivity of the ZIF-8 membrane. The electric field is shown to diminish ion hydration in the confined space of ZIF-8, notably disrupting the orientation of water molecules in the first hydration shells of ions, leading to an asymmetrical ionic hydration structure characterized by the uniform alignment of water dipoles. Furthermore, despite the geometrical constraints imposed by the ZIF-8 framework, the electric field significantly enhances ionic mobility. Notably, the less stable hydration shell of Li+ facilitates its rapid, dehydration-induced transit through ZIF-8 nanopores, unlike Mg2+, whose stable hydration shell impedes dehydration. Further investigation into the structural characteristics of the six-ring windows traversed by Li+ and Mg2+ ions reveals distinct mechanisms of passage: for Mg2+ ions, significant window expansion is necessary, while for Li+ ions, the mechanism involves both window expansion and partial dehydration. These findings reveal the profound impact of the electric field and framework flexibility on the separation of Li+ and Mg2+, offering critical insights for the potential application of flexible nanoporous materials in the selective extraction of Li+ from salt-lake brine.
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Exploring the promiscuity of native enzymes presents a promising strategy for expanding their synthetic applications, particularly for catalyzing challenging reactions in non-native contexts. In this study, we explore the promiscuous potential of old yellow enzymes (OYEs) to facilitate the Morita-Baylis-Hillman reaction (MBH reaction), leveraging substrate similarities between MBH reaction and reduction reaction. Using mass spectrometry and spectroscopic techniques, we confirm promiscuity of GkOYE in both MBH and reduction reactions. By blocking H- and H+ transfer pathways, we engineer GkOYE.8, which loses its reduction ability but enhances its MBH activity. The structural basis of MBH reaction catalyzed by GkOYE.8 is obtained through mutation studies and kinetic simulations. Furthermore, enantiocomplementary mutants GkOYE.11 and GkOYE.13 are obtained by directed evolution, exhibiting the ability to accept various aromatic aldehydes and alkenes as substrates. This study demonstrates the potential of leveraging substrate similarities to unlock enzyme functionalities, enabling the catalysis of new-to-nature reactions.
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Biocatálisis , Especificidad por Sustrato , Cinética , Aldehídos/metabolismo , Aldehídos/química , Catálisis , Mutación , Alquenos/metabolismo , Alquenos/química , Proteínas Bacterianas/metabolismo , Proteínas Bacterianas/genética , Proteínas Bacterianas/química , Ingeniería de ProteínasRESUMEN
Hyperosmotic stress tolerance is crucial for Saccharomyces cerevisiae in producing value-added products from renewable feedstock. The limited understanding of its tolerance mechanism has impeded the application of these microbial cell factories. Previous studies have shown that Med3 plays a role in hyperosmotic stress in S. cerevisiae. However, the specific function of Med3 in hyperosmotic stress tolerance remains unclear. In this study, we showed that the deletion of the mediator Med3 impairs S. cerevisiae growth under hyperosmotic stress. Phenotypic analyses and yeast two-hybrid assays revealed that Med3 interacts with the transcription factor Stb5 to regulate the expression of the genes gnd1 and ald6, which are involved in NADPH production under hyperosmotic stress conditions. The deletion of med3 resulted in a decrease in intracellular NADPH content, leading to increased oxidative stress and elevated levels of intracellular reactive oxygen species under hyperosmotic stress, thereby impacting bud formation. These findings highlight the significant role of Med3 as a regulator in maintaining NADPH generation and redox homeostasis in S. cerevisiae during hyperosmotic stress.IMPORTANCEHyperosmotic stress tolerance in the host strain is a significant challenge for fermentation performance in industrial production. In this study, we showed that the S. cerevisiae mediator Med3 is essential for yeast growth under hyperosmotic conditions. Med3 interacts with the transcription factor Stb5 to regulate the expression of genes involved in the NADPH-generation system during hyperosmotic stress. Adequate NADPH ensures the timely removal of excess reactive oxygen species and supports bud formation under these conditions. This work highlights the crucial role of Med3 as a regulator in maintaining NADPH generation and redox homeostasis in S. cerevisiae during hyperosmotic stress.
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NADP , Presión Osmótica , Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/crecimiento & desarrollo , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , NADP/metabolismo , Factores de Transcripción/metabolismo , Factores de Transcripción/genética , Regulación Fúngica de la Expresión Génica , Estrés Oxidativo , Complejo Mediador/metabolismo , Complejo Mediador/genética , Especies Reactivas de Oxígeno/metabolismoRESUMEN
BACKGROUND Simethicone can improve bowel preparation quality, but the optimal timing of oral simethicone before colonoscopy has not been determined. This study aimed to explore the effect of the time interval between oral simethicone and the start of colonoscopy (S-C) on bowel preparation quality. MATERIAL AND METHODS A total of 364 patients undergoing colonoscopy at our department from August 1, 2021 to November 30, 2021 were included in the training cohort, and 420 consecutive patients from December 15, 2021 to January 31, 2022 comprised the validation cohort. They were classified into short and long S-C groups according to the median S-C. Bowel preparation quality evaluated by the Boston Bowel Preparation Scale was compared between the 2 groups. Logistic regression analyses were performed to explore the correlation between S-C and bowel preparation quality, and we explored the effect of run-way time and time of starting colonoscopy on bowel preparation quality. RESULTS In the training cohort, 182 and 182 patients were classified into the short and long S-C groups, respectively; in the validation cohort, 210 and 210 patients were classified into the 2 groups, respectively. In the 2 cohorts, the short S-C group had a significantly higher rate of adequate/excellent bowel preparation than the long S-C group. Logistic regression analyses showed that shorter S-C, shorter run-way time, and colonoscopy in the morning were all correlated with adequate/excellent bowel preparation. CONCLUSIONS Bowel preparation quality may be affected by S-C, run-way time, and time of starting colonoscopy. S-C shortening should be given equal importance as run-way time shortening.
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Catárticos , Colonoscopía , Simeticona , Humanos , Colonoscopía/métodos , Masculino , Femenino , Simeticona/administración & dosificación , Persona de Mediana Edad , Catárticos/administración & dosificación , Administración Oral , Anciano , Adulto , Factores de TiempoRESUMEN
Understanding the interaction between metal ions as catalytic centers and supramolecular scaffolds as chiral substrates plays an important role in developing chiral supramolecular catalysts with high enantioselectivity. Herein, we found that compared with l-norleucine chiral amphiphile (l-NorC16), l-methionine chiral amphiphile (l-MetC16) with the only heteroatom of S site difference in the hydrophilic group can form a similar supramolecular chiral nanoribbon (NR) with the bilayer structure through the self-assembly approach; yet, the interaction between the Cu(II) ion catalytic centers and supramolecular scaffolds is reinforced, favoring the chirality transfer and therefore enhancing their catalytic enantioselectivity of Diels-Alder reaction from 23% [l-NorC16-NR-Cu(II)] to 78% [l-MetC16-NR-Cu(II)]. Our work demonstrates a new strategy from the perspective of strengthening the metal ion-supramolecular scaffold interaction for the preparation of chiral supramolecular catalysts with good catalytic enantioselectivity.
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Keloid formation has been linked to abnormal fibroblast function, such as excessive proliferation and extracellular matrix (ECM) production. Serum deprivation protein response (SDPR) is a crucial regulator of cellular function under diverse pathological conditions, yet its role in keloid formation remains unknown. The current work investigated the function of SDPR in regulating the proliferation, motility, and ECM production of keloid fibroblasts (KFs), as well as to decipher the mechanisms involved. Analysis of RNA sequencing data from the GEO database demonstrated significant down-regulation of SDPR in KF compared to normal fibroblasts (NFs). This down-regulation was also observed in clinical keloid specimens and isolated KFs. Overexpression of SDPR suppressed the proliferation, motility, and ECM production of KFs, while depletion of SDPR exacerbated the enhancing impact of TGF-ß1 on the proliferation, motility, and ECM production of NFs. Mechanistic studies revealed that SDPR overexpression repressed TGF-ß/Smad signal cascade activation in KFs along with decreased levels of phosphorylated Samd2/3, while SDPR depletion exacerbated TGF-ß/Smad activation in TGF-ß1-stimulated NFs. SDPR overexpression also repressed ERK1/2 activation in KFs, while SDPR depletion exacerbated ERK1/2 activation in TGF-ß1-stimulated NFs. Inhibition of ERK1/2 abolished SDPR-depletion-induced TGF-ß1/Smad activation, cell proliferation, motility, and ECM production in NFs. In conclusion, SDPR represses the proliferation, motility, and ECM production in KFs by blocking the TGF-ß1/Smad pathway in an ERK1/2-dependent manner. The findings highlight the role of SDPR in regulating abnormal behaviors of fibroblasts associated with keloid formation and suggest it as a potential target for anti-keloid therapy development.
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Movimiento Celular , Proliferación Celular , Matriz Extracelular , Fibroblastos , Queloide , Sistema de Señalización de MAP Quinasas , Proteínas Smad , Factor de Crecimiento Transformador beta1 , Humanos , Queloide/patología , Queloide/metabolismo , Queloide/genética , Fibroblastos/efectos de los fármacos , Fibroblastos/metabolismo , Proliferación Celular/efectos de los fármacos , Movimiento Celular/efectos de los fármacos , Factor de Crecimiento Transformador beta1/metabolismo , Matriz Extracelular/metabolismo , Matriz Extracelular/efectos de los fármacos , Proteínas Smad/metabolismo , Sistema de Señalización de MAP Quinasas/efectos de los fármacos , Sistema de Señalización de MAP Quinasas/fisiología , Transducción de Señal , Células Cultivadas , Proteína Quinasa 1 Activada por Mitógenos/metabolismo , Masculino , Femenino , Proteína Quinasa 3 Activada por Mitógenos/metabolismo , AdultoRESUMEN
Para-hydroxybenzoic acid (PHBA) is extensively used as an additive in the food and cosmetics industries, significantly enhancing product shelf life and stability. While microbial fermentation offers an environment-friendly and sustainable method for producing PHBA, the titer and productivity are limited due to product toxicity and complex metabolic flux distributions. Here, we initially redesigned a L-phenylalanine-producing Escherichia coli by employing rational metabolic engineering strategies, resulting in the production of PHBA reached the highest reported level of 14.17 g/L. Subsequently, a novel accelerated evolution system was devised comprising deaminase, the alpha subunit of RNA polymerase, an uracil-DNA glycosylase inhibitor, and the PHBA-responsive promoter PyhcN. This system enabled us to obtain a mutant strain exhibiting a 47% increase in the half-inhibitory concentration (IC50) for PHBA within 15 days. Finally, the evolved strain achieved a production of 21.35 g/L PHBA in a 5-L fermenter, with a yield of 0.19 g/g glucose and a productivity rate of 0.44 g/L/h. This engineered strain emerges as a promising candidate for industrial production of PHBA through an eco-friendly approach.
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Escherichia coli , Fermentación , Ingeniería Metabólica , Parabenos , Escherichia coli/genética , Escherichia coli/metabolismo , Parabenos/metabolismoRESUMEN
We conducted a study on the trajectory-dependent threshold effects of proton stopping power in LiF nanosheets using time-dependent density functional theory non-adiabatically coupled to the molecular dynamics. This study covered protons with initial velocities in the range of 0.1-1.0 a.u., offering a vast amount of detailed information on the electronic structure during the stopping process with superior spatial and temporal resolution. Our results show that the impact parameters of incident protons play a crucial role in determining the threshold behavior of proton stopping power in LiF nanosheets. Most importantly, we found that close collisions do not exhibit a discernible threshold. In addition, the research results also revealed the time dependence of the number of electrons occupying the atomic orbitals of F and Li as protons pass through the nanosheets.
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Noncontact sensing technology serves as a pivotal medium for seamless data acquisition and intelligent perception in the era of the Internet of Things (IoT), bringing innovative interactive experiences to wearable human-machine interaction perception networks. However, the pervasive limitations of current noncontact sensing devices posed by harsh environmental conditions hinder the precision and stability of signals. In this study, the triboelectric nanopaper prepared by a phase-directed assembly strategy is presented, which possesses low charge transfer mobility (1618 cm2 V-1 s-1) and exceptional high-temperature stability. Wearable self-powered noncontact sensors constructed from triboelectric nanopaper operate stably under high temperatures (200 °C). Furthermore, a temperature warning system for workers in hazardous environments is demonstrated, capable of nonintrusively identifying harmful thermal stimuli and detecting motion status. This research not only establishes a technological foundation for accurate and stable noncontact sensing under high temperatures but also promotes the sustainable intelligent development of wearable IoT devices under extreme environments.
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The brown planthopper (Nilaparvata lugens) is a major destructive rice pest in Asia. High levels of insecticide resistance have been frequently reported, and the G932C mutation in the chitin synthase 1 (CHS1) gene has been found to mediate buprofezin resistance. However, there has been no direct evidence to confirm the functional significance of the single G932C substitution mutation leading to buprofezin resistance in N. lugens. Here, we successfully constructed a knock-in homozygous strain (Nl-G932C) of N. lugens using CRISPR/Cas9 coupled with homology-directed repair (HDR). Compared with the background strain susceptible to buprofezin (Nl-SS), the knock-in strain (Nl-G932C) showed a 94.9-fold resistance to buprofezin. Furthermore, resistant strains (Nl-932C) isolated from the field exhibited a 2078.8-fold resistance to buprofezin, indicating that there are other mechanisms contributing to buprofezin resistance in the field. Inheritance analysis showed that the resistance trait is incomplete dominance. In addition, the Nl-G932C strain had a relative fitness of 0.33 with a substantially decreased survival rate, emergence rate, and fecundity. This study provided in vivo functional evidence for the causality of G932C substitution mutation of CHS1 with buprofezin resistance and valuable information for facilitating the development of resistance management strategies in N. lugens. This is the first example of using CRISPR/Cas9 gene-editing technology in a hemipteran insect to directly confirm the role of a candidate target site mutation in insecticide resistance.
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Sistemas CRISPR-Cas , Quitina Sintasa , Hemípteros , Resistencia a los Insecticidas , Insecticidas , Tiadiazinas , Animales , Hemípteros/genética , Resistencia a los Insecticidas/genética , Tiadiazinas/farmacología , Quitina Sintasa/genética , Insecticidas/farmacología , Mutación , Proteínas de Insectos/genética , Proteínas de Insectos/metabolismo , Técnicas de Sustitución del Gen , Femenino , MasculinoRESUMEN
Aromatic d-amino acids (d-AAs) play a pivotal role as important chiral building blocks and key intermediates in fine chemical and drug synthesis. Meso-diaminopimelate dehydrogenase (DAPDH) serves as an excellent biocatalyst in the synthesis of d-AAs and their derivatives. However, its strict substrate specificity and the lack of efficient engineering methods have hindered its widespread application. Therefore, this study aims to elucidate the catalytic mechanism underlying DAPDH from Proteus vulgaris (PvDAPDH) through the examination of its crystallographic structure, computational simulations of potential energies and molecular dynamics simulations, and site-directed mutagenesis. Mechanism-guided computational design showed that the optimal mutant PvDAPDH-M3 increased specific activity and catalytic efficiency (kcat/Km) for aromatic keto acids up to 124-fold and 92.4-fold, respectively, compared to that of the wild type. Additionally, it expanded the substrate scope to 10 aromatic keto acid substrates. Finally, six high-value-added aromatic d-AAs and their derivatives were synthesized using a one-pot three-enzyme cascade reaction, exhibiting a good conversion rate ranging from 32 to 84% and excellent stereoselectivity (enantiomeric excess >99%). These findings provide a potential synthetic pathway for the green industrial production of aromatic d-AAs.
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Aminoácido Oxidorreductasas , Aminoácidos Aromáticos , Simulación de Dinámica Molecular , Mutagénesis Sitio-Dirigida , Aminoácido Oxidorreductasas/metabolismo , Aminoácido Oxidorreductasas/genética , Aminoácido Oxidorreductasas/química , Especificidad por Sustrato , Aminoácidos Aromáticos/metabolismo , Aminoácidos Aromáticos/biosíntesis , Proteus vulgaris/enzimología , Proteus vulgaris/genética , Biocatálisis , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Proteínas Bacterianas/químicaRESUMEN
The hydroxylation of remote C(sp3)-H bonds in aliphatic amino acids yields crucial precursors for the synthesis of high-value compounds. However, accurate regulation of the regioselectivity of remote C(sp3)-H bonds hydroxylation in aliphatic amino acids continues to be a common challenge in chemosynthesis and biosynthesis. In this study, the Fe(II)/α-ketoglutarate-dependent dioxygenase from Bacillus subtilis (BlAH) was mined and found to catalyze hydroxylation at the γ and δ sites of aliphatic amino acids. Crystal structure analysis, molecular dynamics simulations, and quantum chemical calculations revealed that regioselectivity was regulated by the spatial effect of BlAH. Based on these results, the spatial effect of BlAH was reconstructed to stabilize the transition state at the δ site of aliphatic amino acids, thereby successfully reversing the γ site regioselectivity to the δ site. For example, the regioselectivity of L-Homoleucine (5 a) was reversed from the γ site (1 : 12) to the δ site (>99 : 1). The present study not only expands the toolbox of biocatalysts for the regioselective functionalization of remote C(sp3)-H bonds, but also provides a theoretical guidance for the precision-driven modification of similarly remote C(sp3)-H bonds in complex molecules.
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Aminoácidos , Bacillus subtilis , Dioxigenasas , Ácidos Cetoglutáricos , Hidroxilación , Bacillus subtilis/enzimología , Dioxigenasas/metabolismo , Dioxigenasas/química , Ácidos Cetoglutáricos/metabolismo , Ácidos Cetoglutáricos/química , Aminoácidos/química , Aminoácidos/metabolismo , Estereoisomerismo , Compuestos Ferrosos/química , Compuestos Ferrosos/metabolismo , Simulación de Dinámica MolecularRESUMEN
Microbial synthetic epigenetics offers significant opportunities for the design of synthetic biology tools by leveraging reversible gene control mechanisms without altering DNA sequences. However, limited understanding and a lack of technologies for thorough analysis of the mechanisms behind epigenetic modifications have hampered their utilization in biotechnological applications. In this review, we explore advancements in developing epigenetic-based synthetic gene regulatory tools at both transcriptional and post-transcriptional levels. Furthermore, we examine strategies developed to construct epigenetic-based circuits that provide controllable and stable gene regulation, aiming to boost the performance of microbial chassis cells. Finally, we discuss the current challenges and perspectives in the development of synthetic epigenetic tools.
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Epigénesis Genética , Biología Sintética , Biología Sintética/métodos , Epigénesis Genética/genética , Bacterias/genética , Redes Reguladoras de Genes/genética , Biotecnología/métodosRESUMEN
BACKGROUND: Perihematomal edema (PHE) after post-intracerebral hemorrhage (ICH) has complex pathophysiological mechanisms that are poorly understood. The complicated immune response in the post-ICH brain constitutes a crucial component of PHE pathophysiology. In this study, we aimed to characterize the transcriptional profiles of immune cell populations in human PHE tissue and explore the microscopic differences between different types of immune cells. METHODS: 9 patients with basal ganglia intracerebral hemorrhage (hematoma volume 50-100 ml) were enrolled in this study. A multi-stage profile was developed, comprising Group1 (n = 3, 0-6 h post-ICH, G1), Group2 (n = 3, 6-24 h post-ICH, G2), and Group3 (n = 3, 24-48 h post-ICH, G3). A minimal quantity of edematous tissue surrounding the hematoma was preserved during hematoma evacuation. Single cell RNA sequencing (scRNA-seq) was used to map immune cell populations within comprehensively resected PHE samples collected from patients at different stages after ICH. RESULTS: We established, for the first time, a comprehensive landscape of diverse immune cell populations in human PHE tissue at a single-cell level. Our study identified 12 microglia subsets and 5 neutrophil subsets in human PHE tissue. What's more, we discovered that the secreted phosphoprotein-1 (SPP1) pathway served as the basis for self-communication between microglia subclusters during the progression of PHE. Additionally, we traced the trajectory branches of different neutrophil subtypes. Finally, we also demonstrated that microglia-produced osteopontin (OPN) could regulate the immune environment in PHE tissue by interacting with CD44-positive cells. CONCLUSIONS: As a result of our research, we have gained valuable insight into the immune-microenvironment within PHE tissue, which could potentially be used to develop novel treatment modalities for ICH.
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Edema Encefálico , Hemorragia Cerebral , Progresión de la Enfermedad , Análisis de Secuencia de ARN , Análisis de la Célula Individual , Humanos , Edema Encefálico/inmunología , Edema Encefálico/patología , Edema Encefálico/genética , Edema Encefálico/metabolismo , Edema Encefálico/etiología , Hemorragia Cerebral/inmunología , Hemorragia Cerebral/patología , Hemorragia Cerebral/genética , Masculino , Femenino , Persona de Mediana Edad , Análisis de Secuencia de ARN/métodos , Anciano , Hematoma/patología , Hematoma/inmunología , Hematoma/genéticaRESUMEN
The widespread attention towards 1,4-butanediol (BDO) as a key chemical raw material stems from its potential in producing biodegradable plastics. However, the efficiency of its biosynthesis via current bioprocesses is limited. In this study, a dual-pathway approach for 1,4-BDO production from succinic acid was developed. Specifically, a double-enzyme catalytic pathway involving carboxylic acid reductase and ethanol dehydrogenase was proposed. Optimization of the expression levels of the pathway enzymes led to a significant 318 % increase in 1,4-BDO titer. Additionally, the rate-limiting enzyme MmCAR was engineered to enhance the kcat/KM values by 50 % and increase 1,4-BDO titer by 46.7 %. To address cofactor supply limitations, an NADPH and ATP cycling system was established, resulting in a 48.9 % increase in 1,4-BDO production. Ultimately, after 48â hours, 1,4-BDO titers reached 201â mg/L and 1555â mg/L in shake flask and 5â L fermenter, respectively. This work represents a significant advancement in 1,4-BDO synthesis from succinic acid, with potential applications in the organic chemical and food industries.
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Butileno Glicoles , Escherichia coli , Ácido Succínico , Butileno Glicoles/metabolismo , Butileno Glicoles/química , Ácido Succínico/metabolismo , Ácido Succínico/química , Escherichia coli/metabolismo , Escherichia coli/genética , Biocatálisis , Alcohol Deshidrogenasa/metabolismo , Oxidorreductasas/metabolismo , Oxidorreductasas/genética , FermentaciónRESUMEN
Cadaverine is a critical C5 monomer for the production of polyamides. Pyridoxal 5'-phosphate (PLP), as a crucial cofactor for the key enzyme lysine decarboxylase in the cadaverine biosynthesis pathway, has seen a persistent shortage, leading to limitations in cadaverine production. To address this issue, a dual-pathway strategy was implemented, synergistically enhancing both endogenous and heterologous PLP synthesis modules and resulting in improved PLP synthesis. Subsequently, a growth-stage-dependent molecular switch was introduced to balance the precursor competition between PLP synthesis and cell growth. Additionally, a PLP sensor-based negative feedback circuit was constructed by integrating a newly identified PLP-responsive promoter PygjH and an arabinose-regulated system, dynamically regulating the expression of the PLP synthetic genes and preventing excessive intracellular PLP accumulation. The optimal strain, L18, cultivated in the minimal medium AM1, demonstrated cadaverine production with a titer, yield, and productivity of 64.03 g/L, 0.23 g/g glucose, and 1.33 g/L/h, respectively. This represents the highest titer reported to date in engineered Escherichia coli by fed-batch fermentation in a minimal medium.
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Cadaverina , Medios de Cultivo , Escherichia coli , Ingeniería Metabólica , Fosfato de Piridoxal , Cadaverina/metabolismo , Cadaverina/biosíntesis , Fosfato de Piridoxal/metabolismo , Escherichia coli/genética , Escherichia coli/metabolismo , Ingeniería Metabólica/métodos , Medios de Cultivo/química , Regiones Promotoras Genéticas , Carboxiliasas/genética , Carboxiliasas/metabolismoRESUMEN
l-Phenylalanine (l-Phe) is widely used in the food and pharmaceutical industries. However, the biosynthesis of l-Phe using Escherichia coli remains challenging due to its lower tolerance to high concentration of l-Phe. In this study, to efficiently synthesize l-Phe, the l-Phe biosynthetic pathway was reconstructed by expressing the heterologous genes aroK1, aroL1, and pheA1, along with the native genes aroA, aroC, and tyrB in the shikimate-producing strain E. coli SA09, resulting in the engineered strain E. coli PHE03. Subsequently, adaptive evolution was conducted on E. coli PHE03 to enhance its tolerance to high concentrations of l-Phe, resulting in the strain E. coli PHE04, which reduced the cell mortality to 36.2% after 48 h of fermentation. To elucidate the potential mechanisms, transcriptional profiling was conducted, revealing MarA, a DNA-binding transcriptional dual regulator, as playing a crucial role in enhancing cell membrane integrity and fluidity for improving cell tolerance to high concentrations of l-Phe. Finally, the titer, yield, and productivity of l-Phe with E. coli PHE05 overexpressing marA were increased to 80.48 g/L, 0.27 g/g glucose, and 1.68 g/L/h in a 5-L fed-batch fermentation, respectively.
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Escherichia coli , Fermentación , Ingeniería Metabólica , Fenilalanina , Escherichia coli/genética , Escherichia coli/metabolismo , Fenilalanina/metabolismo , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Vías BiosintéticasRESUMEN
Rapid advancements in flexible electronics technology propel soft tactile sensing devices toward high-level biointegration, even attaining tactile perception capabilities surpassing human skin. However, the inherent mechanical mismatch resulting from deficient biomimetic mechanical properties of sensing materials poses a challenge to the application of wearable tactile sensing devices in human-machine interaction. Inspired by the innate biphasic structure of human subcutaneous tissue, this study discloses a skin-compliant wearable iontronic triboelectric gel via phase separation induced by competitive hydrogen bonding. Solvent-nonsolvent interactions are used to construct competitive hydrogen bonding systems to trigger phase separation, and the resulting soft-hard alternating phase-locked structure confers the iontronic triboelectric gel with Young's modulus (6.8-281.9 kPa) and high tensile properties (880%) compatible with human skin. The abundance of reactive hydroxyl groups gives the gel excellent tribopositive and self-adhesive properties (peel strength > 70 N m-1). The self-powered tactile sensing skin based on this gel maintains favorable interface and mechanical stability with the working object, which greatly ensures the high fidelity and reliability of soft tactile sensing signals. This strategy, enabling skin-compliant design and broad dynamic tunability of the mechanical properties of sensing materials, presents a universal platform for broad applications from soft robots to wearable electronics.