Search Results (220)

Global energy supply remains, to this day, mainly dominated by fossil fuels, aggravating climate change. To increase and diversify the share of renewable energy sources, there is an urgent need to expand the use of biofuels that could help in decarbonizing the energy mix. Biomethane, obtained by upgrading biogas, simultaneously allows the local production of clean energy, waste valorization, and greenhouse gas emissions mitigation. Among various upgrading technologies, the use of activated carbons in adsorption-based separation systems has attracted significant attention due to their versatility, cost-effectiveness, and sustainability potential. The present review offers a comprehensive analysis of the factors that influence the efficiency of activated carbons on carbon dioxide adsorption and separation for biogas upgrading. The influence of activation methods, activation conditions, and precursors on the biogas adsorption performance of activated carbons is revised. Additionally, the role of adsorbent textural and chemical properties on gas adsorption behavior is highlighted. By synthesizing current knowledge and perspectives, this work provides guidance for future research that could help in developing more efficient, cost-effective, and sustainable adsorbents for biogas upgrading. Full article

The filamentous fungal genus Aspergillus represents an industrially significant group of eukaryotic microorganisms. For nearly a century, it has been widely utilized in the production of diverse high-value products, including organic acids, industrial enzymes, recombinant proteins, and various bioactive natural compounds. With the rapid advancement of synthetic biology, Aspergillus has been extensively exploited as a heterologous chassis for the production of heterologous proteins (e.g., sweet proteins and antibodies) and the synthesis of natural products (e.g., terpenoids and polyketides) due to its distinct advantages, such as superior protein secretion capacity, robust precursor supply, and efficient eukaryotic post-translational modifications. In this review, we provide a comprehensive summary of the advancements in the successful expression of heterologous proteins and the biosynthesis of natural products using Aspergillus platforms (including Aspergillus niger, Aspergillus nidulans, and Aspergillus oryzae) in recent years. Emphasis is placed on the applications of A. oryzae in the heterologous biosynthesis of terpenoids. More importantly, we thoroughly examine the current state of the art in utilizing CRISPR-Cas9 for genetic modifications in A. oryzae and A. niger. In addition, future perspectives on developing Aspergillus expression systems are discussed in this article, along with an exploration of their potential applications in natural product biosynthesis. Full article

Mandelic acid (MA) is a valuable α-hydroxy acid with applications in pharmaceuticals, cosmetics, and fine chemicals. While chemical synthesis is well established, concerns over toxicity and sustainability have driven interest in microbial production. Here, we engineered Escherichia coli for de novo MA biosynthesis by integrating enzyme screening, metabolic flux optimization, and pathway regulation. We first screened and identified an efficient hydroxymandelate synthase (HMAS) homolog from Actinosynnema mirum for MA synthesis, and subsequently enhanced the shikimate pathway along with the supply of the precursors erythrose-4-phosphate (E4P) and phosphoenolpyruvate (PEP). Additionally, CRISPR interference (CRISPRi) was employed to repress competing pathways and redirect flux toward MA production. High-cell-density cultivation (HCDC) in a 5 L bioreactor demonstrated the strain’s industrial potential, achieving an MA titer of 9.58 g/L, the highest reported for microbial production. This study provides a systematic metabolic engineering approach for efficient MA biosynthesis from glucose, offering a foundation for sustainable large-scale production, demonstrating not only genetic-level optimizations, but also effective process scaling through high-cell-density cultivation, highlighting the power of pathway engineering in microbial cell factories. Full article

Novel Bi₂S₃/Bi₂O₃ hybrid materials with unique mesoporous structures were successfully synthesized via a facile in situ elevated-temperature thermal oxidation method using the Bi₂S₃ as a precursor in air. The as-prepared Bi₂S₃/Bi₂O₃ heterostructure-based sensor exhibits an excellent performance for detecting sub-ppm concentrations of NO₂ at room temperature (RT). In the presence of 8 ppm NO₂, the sensor registers a response of approximately 7.85, reflecting a 3.5-fold increase compared to the pristine Bi₂S₃-based sensor. The response time is 71 s, while the recovery time is 238 s, which are reduced by 32.4% and 24.2%, respectively, compared to the pristine Bi₂S₃-based sensor. The Bi₂S₃/Bi₂O₃ heterostructure-based sensor achieves an impressively low detection limit of 0.1 ppm for NO₂, and the sensor has been demonstrated to possess superior signal repeatability, gas selectivity, and long-term stability. The optimal preparation conditions of the hybrid materials were explored, and the formation of mesoporous structure was analyzed. The obviously improved gas sensitivity of the Bi₂S₃/Bi₂O₃ heterostructure-based sensor can be assigned to the combined influence of electronic sensitization and its distinctive morphological structure. The potential gas-sensitive mechanisms were revealed by employing density functional theory (DFT). It was found that the formation of heterostructures could enhance the adsorption energies and increase the amount of electron transfer between NO₂ molecules and the hybrid materials. Furthermore, the electron redistribution driven by orbital hybridization between O and Bi atoms improves the capacity of NO₂ molecules to capture additional electrons from the Bi₂S₃/Bi₂O₃ heterostructures. The content of this work supplies an innovative design strategy for constructing NO₂ sensor with high performance and low energy consumption at RT. Full article

To better analyze the biosynthesis mechanism of cephalosporin C (CPC) in Acremonium chrysogenum, single-factor omission experiments and Plackett–Burman (PB) experimental design were employed to identify key components in the chemically defined medium. Response surface methodology (RSM) was then applied to optimize the concentrations of critical factors, achieving a final CPC titer of 4.70 g/L, which reached 59.54% of the titer obtained with complex medium. Methionine was identified as the most significant amino acid influencing CPC production during medium optimization. On the basis of these findings, transcriptomic analysis was conducted to elucidate the regulatory role of methionine. The results revealed that methionine enhances CPC biosynthesis by upregulating cysteine metabolism-related genes and activating primary metabolic pathways to supply precursors and energy for secondary metabolism. Additionally, methionine promoted hyphal swelling and arthrospore formation, leading to the upregulated expression of genes in CPC biosynthetic gene clusters. By integrating medium optimization with transcriptomic analysis, we provided more reliable insights into the regulatory role of methionine in A. chrysogenum growth and CPC biosynthesis using a chemically defined medium, offering valuable guidance for fermentation process optimization and subsequent metabolic engineering strategies. Full article

As high-quality sheep germplasm resources in China, Hu sheep are characterized by fast growth and development, high fecundity, and tolerance to drought and cold. Tibetan sheep, adapted to high-altitude environments, have developed strong environmental adaptability. To explore the differences in the interaction among rumen microbial flora, hepatic gluconeogenesis, and mitochondrial function between Tibetan sheep and Hu sheep in the Qinghai–Tibet Plateau, this study systematically compared and analyzed the rumen flora density, key enzyme activities related to hepatic gluconeogenesis and mitochondrial function, and the expression levels of related genes in Tibetan sheep and Hu sheep under identical feeding management conditions, followed by correlation analysis. The results showed that Hu sheep had significantly higher densities of Ruminobacteramylophilus (Ram) and Fibrobacter succinogenes (Fs) associated with starch and protein degradation (p < 0.01). The expression levels of Forkhead box O1 (FOXO1), pyruvate carboxylase (PC) activity, and adenosine triphosphate (ATP) content were also significantly higher than those in Tibetan sheep (p < 0.01). In contrast, Tibetan sheep had higher densities of Butyrivibrio fibrisolvens (Bf), Ruminococcus albus (Ra), Ruminococcus flavefaciens (Rf), etc., related to cellulose degradation (p < 0.01). The gluconeogenesis-related genes, Glucose-6-phosphatase catalytic subunit 1 (G6PC1) and phosphoenolpyruvate carboxykinase1 (PCK1), and the activities of phosphoenolpyruvate carboxykinase (PEPCK) and fructose-1,6-bisphosphatase (FBPase) were significantly higher in Tibetan sheep than in Hu sheep (p < 0.01). Mitochondrial function-related genes Mitofusin-1 (Mfn1), Mitofusin-2 (Mfn2), subunit 6 of ATP synthase (ATP6), cytochrome b (Cytb), etc., also showed significantly higher expression in Tibetan sheep (p < 0.01). While no significant differences were observed in the contents of citric acid (CA), pyruvic acid (PA), glucose (Glu), etc. (p > 0.05). Correlation analysis indicated that rumen flora was associated with the key enzyme activities and gene expressions of hepatic gluconeogenesis and mitochondrial function to varying degrees. In summary, Tibetan sheep exhibit strong fiber degradation capacity, the efficient utilization of gluconeogenic intermediates, and mitochondrial oxidative phosphorylation (OXPHOS) ability, forming adaptive strategies for high-altitude environments. By contrast, Hu sheep show efficient protein and starch degradation capacity, thereby enhancing the supply of gluconeogenic precursors. It is indicated that when introducing Hu sheep to high-altitude areas, dietary intervention can be used to regulate rumen microorganisms, such as increasing fiber-decomposing bacteria or enhancing mitochondrial oxidative capacity, to counteract metabolic limitations induced by hypoxia. Full article

Cold stress critically restricts maize seedling growth in Northeast China, yet the mechanism by which cold priming (CP) enhances cold tolerance through proline–nitrogen metabolic networks remains unclear. This study systematically investigated CP’s synergistic regulation in cold-tolerant (Heyu27) and cold-sensitive (Dunyu213) maize using a two-phase temperature regime (priming induction/stress response) with physiological and multivariate analyses. CP alleviated cold-induced photosynthetic inhibition while maintaining a higher chlorophyll and photosynthetic rate, though biomass responses showed varietal specificity, with Heyu27 minimizing growth loss through optimized carbon–nitrogen allocation. Antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) were pre-activated during early stress, effectively scavenging reactive oxygen species (ROS) and reducing malondialdehyde (MDA) accumulation, with Heyu27 showing superior redox homeostasis. CP enhanced proline accumulation via bidirectional enzyme regulation (upregulating ∆¹-pyrroline-5-carboxylate synthase/reductase [P5CS/P5CR], inhibiting proline dehydrogenase [ProDH]) and reprogrammed nitrogen metabolism through glutamate dehydrogenase/isocitrate dehydrogenase (GDH/ICDH)-mediated ammonium conversion to glutamate, alleviating nitrogen dysregulation while supplying proline precursors. Principal component analysis revealed divergent strategies: Heyu27 prioritized proline–antioxidant synergy, whereas Dunyu213 emphasized photosynthetic adjustments. These findings demonstrate that CP establishes “metabolic memory” through optimized proline–nitrogen coordination, synergistically enhancing osmoregulation, reactive oxygen species (ROS) scavenging, and nitrogen utilization. This study elucidates C₄-specific cold adaptation mechanisms, advancing cold-resistant breeding and stress-resilient agronomy. Full article

The demand for L-tryptophan (L-Trp) has been rapidly increasing across various industries, including pharmaceuticals, food, and animal feed. However, traditional production methods have been unable to efficiently meet this growing demand. Hence, this study aimed to develop strategies for enhancing L-Trp production in Escherichia coli. Firstly, an L-Trp-producing strain was selected and subjected to atmospheric and room temperature plasma (ARTP) mutagenesis to generate a mutant library. This was followed by high-throughput screening using an L-Trp-specific riboswitch and a yellow fluorescent protein (YFP)-based biosensor in a flow cytometric cell sorting (FACS) system. Among the screened mutants, GT3938 exhibited a 1.94-fold increase in L-Trp production. Subsequently, rational metabolic engineering was applied to GT3938 by knocking out the L-Trp intracellular transporter gene (tnaB), enhancing the expression of the aromatic amino acid exporter (YddG) and optimizing precursor supply pathways. The resulting strain, zh08, achieved an L-Trp titer of 3.05 g/L in shake-flask fermentation, representing a 7.71-fold improvement over the original strain. This study demonstrated an effective strategy for industrial strain development by integrating biosensor-assisted, high-throughput screening with rational metabolic engineering. Full article

Vibrio natriegens (V. natriegens) is an emerging synthetic biology chassis characterized by rapid growth, and its potential for the synthesis of sesquiterpenes (such as pentalenene) has not been developed. In this study, heterologous pentalenene biosynthesis was successfully established in V. natriegens via metabolic engineering. The optimization of gene dosage and culture conditions led to an increase in pentalenene yield from 0.75 mg/L to 39.4 mg/L, representing the highest titer reported in V. natriegens to date, though still markedly lower than yields achieved in conventional microbial hosts. Transcriptome analysis demonstrated that the exogenous mevalonate (MVA) pathway effectively activated terpenoid precursor synthesis, as evidenced by the up-regulation of key pathway genes. However, the endogenous methylerythritol 4-phosphate (MEP) pathway remained inactive, and genes involved in oxidative phosphorylation, the pentose phosphate pathway, and thiamine biosynthesis were down-regulated, leading to limited availability of ATP, NADPH, and acetyl-CoA. Competition for cofactors, particularly NADPH, further constrained precursor supply and pathway efficiency. This study confirmed the potential of V. natriegens as a pentalenene production platform and revealed its metabolic bottleneck, providing a theoretical basis for subsequent engineering optimization. Full article

Currently, various types of myoglobins and hemoglobins are widely used in the fields of food additives and biocatalytic applications. However, the limited availability of heme constrains the biosynthesis of these high-activity hemoproteins in microbial chassis cells. In this work, a new heme synthetic pathway was reconstructed in the mitochondria by eliminating the spatial barrier during heme synthesis in Saccharomyces cerevisiae, resulting in a significant enhancement in intracellular heme supply. To further enhance the supply of the essential precursor for heme synthesis (5-aminolevulinate, ALA), the special ALA exporter in the mitochondrial membrane (Ort1p) was identified and knocked out. Moreover, the mitochondrial heme exporter (Ygr127wp) was overexpressed to promote the transport of heme to the cytoplasm to participate in the synthesis of various myoglobins and hemoglobins. Based on these strategies in the engineered strain, the binding ratios of heme in porcine myoglobin (52.4 ± 4.9%) and soybean hemoglobin (75.5 ± 2.8%) were, respectively, increased by 2.4-fold and 3.6-fold, and the titers of porcine myoglobin (130.5 ± 2.8 mg·L⁻¹) and soybean hemoglobin (152.8 ± 2.6 mg·L⁻¹), respectively, increased by 31.1% and 42.1%. Furthermore, the engineered strain presents great potential in the efficient synthesis of other heme-binding proteins and enzymes in S. cerevisiae. Full article

Isoflavones are important secondary metabolites in leguminous plants with significant physiological functions and economic value. However, the genetic variation, transcriptional regulation, and metabolic pathways governing isoflavone biosynthesis in Trifolium pratense remain largely unexplored. In this study, we systematically analyzed 500 accessions of T. pratense for isoflavone content and performed RNA-seq-based transcriptomic profiling to investigate the molecular mechanisms underlying isoflavone biosynthesis. Cluster analysis revealed significant genetic variation, with distinct transcriptional profiles between high- (H1, H2, H3) and low-isoflavone (L1, L2, L3) groups. GO and KEGG pathway enrichment analyses identified key metabolic pathways, including phenylpropanoid metabolism, flavonoid biosynthesis, carbohydrate metabolism, and hormone signaling, which play crucial roles in isoflavone regulation. Weighted gene co-expression network analysis (WGCNA) identified three key gene modules—MEblue, MEturquoise, and MEyellow—strongly correlated with isoflavone content. The MEturquoise and MEyellow modules were upregulated in high-isoflavone groups and were enriched in phenylpropanoid biosynthesis, lipid metabolism, and transcriptional regulation, suggesting that these pathways actively promote isoflavone accumulation. Conversely, the MEblue module, highly expressed in low-isoflavone groups, was enriched in sugar metabolism and MAPK signaling, indicating a potential metabolic flux shift away from secondary metabolism. Moreover, key rate-limiting enzymes (PAL, C4H, 4CL, CHS, and IFS) exhibited higher expression in high-isoflavone groups, highlighting their importance in precursor supply and enzymatic catalysis. Additionally, transcription factors such as MYB, WRKY, and NAC were identified as potential regulators of isoflavone biosynthesis, indicating a complex interplay between hormonal, circadian, and environmental signals. This study provides a comprehensive molecular framework for understanding isoflavone biosynthesis in T. pratense and identifies key regulatory genes and metabolic pathways that could be targeted for genetic improvement, metabolic engineering, and molecular breeding. The findings offer valuable insights into enhancing isoflavone production in legumes for agricultural, nutritional, and pharmaceutical applications. Full article

Sustainable bio-based epoxy technology is developed by using bio-based epoxy materials instead of conventional fossil-derived ones. Significant progress in new bio-based epoxy material development on bio-based epoxy resins, curing agents, and additives, as well as bio-based epoxy formulated products, has been achieved recently not only in fundamental academic studies but also in industrial product development. There are mainly two types of bio-based epoxy resins: conventional epoxy resins and novel epoxy resins, depending on the epoxy resin building-block type used. Bio-based conventional epoxy resins are prepared by using the bio-based epichlorohydrin to replace conventional fossil-based epichlorohydrin. Bio-based novel epoxy resins are usually prepared from epoxidation of renewable precursors such as unsaturated vegetable oils, saccharides, tannins, cardanols, terpenes, rosins, and lignin. Typical bio-based curing agents are bio-based polyamines, polyamides, amidoamines, and cardanol-based phenalkamine-type curing agents. Cardanol is a typical bio-based reactive additive available commercially. Certain types of partially bio-based formulated epoxy products have been developed and supplied for use in bonding, coating, casting, composite, and laminating applications. Full article

This review examines the relationship between cholesterol and bone resorption. It seeks to elucidate the dependence of bone turnover on cholesterol metabolism by highlighting the common inhibitory effect of both statins and nitrogen-containing bisphosphonates on cholesterol biosynthesis and bone resorption as well as on bone density. Moreover, this paper also discusses the epidemiologic studies of the effects of nitrogen-containing bisphosphonates on all-cause and cardiovascular mortality using the latest publications to reinforce the relationship between bone resorption and cardiovascular disease. This review will also discuss the role of lipoproteins in supplying cholesterol to both osteoclasts and osteoblasts and the effects of doing so on both of these bone cells and their precursors. As inflammation is a major factor in both bone resorption and cardiovascular calcification, this article will also discuss the role of cholesterol in triggering inflammatory responses. Finally, this paper will raise questions unanswered to date that bear on the relationship between lipid metabolism, bone resorption, and cardiovascular disease. Full article

Soybean production is currently insufficient to meet global demand, highlighting the need for strategies to enhance growth. Melatonin (MT) has emerged as a promising solution due to its growth-promoting properties. This study investigated the effects of a dual MT treatment—combining seed soaking and foliar spraying—on soybean carbon and nitrogen metabolism using metabolomics analysis. The results demonstrated that MT treatment significantly upregulated the TCA cycle, providing energy and precursors for amino acid and carbohydrate synthesis. Key amino acid pathways, including histidine and phenylalanine metabolism, were enhanced, with histidine metabolism stimulating purine synthesis to improve biological nitrogen fixation and phenylalanine metabolism promoting secondary metabolite production to support growth. Additionally, carbohydrate pathways such as starch and sucrose metabolism and glycolysis/gluconeogenesis were positively regulated, ensuring energy supply and carbon homeostasis. Overall, dual MT treatment enhanced soybean metabolic capacity by promoting amino acid and carbohydrate metabolism, stimulating purine and secondary metabolite production, and maintaining carbon and nitrogen balance. These findings underscore melatonin’s regulatory role in soybean growth and provide insights for improving crop productivity. Full article

For industrial CO₂ utilization, the supply of concentrated CO₂ within a continuous, high-volume stream at high temperatures remains a substantial requirement. Membrane processes offer a simple and efficient method to provide CO₂ in this form. While several organo-silica-based membranes have been developed for CO₂/N₂ separation under these conditions, there is no standardized framework guiding comparability and optimization. Therefore, we present these membranes in a Robeson-like plot across various temperatures. Utilizing a standard 1,2-bis(triethoxysilyl)-ethane (BTESE) precursor and a simplified sol–gel method, we prepared a microporous membrane layer and characterized it for an exemplary comparison. This characterization includes key parameters for mixed-gas applications: (1) temperature-dependent single- and mixed-gas permeances to observe interactions, (2) the impact of the driving forces in mixtures (vacuum and concentration) to distinguish between permselectivity and the separation factor clearly, and (3) influence of the support structure to enable permeability calculations at elevated temperatures. Furthermore, a quick interpretation method for assessing the membrane’s microstructure is presented. A qualitative microstructure assessment can be achieved by analyzing the temperature dependencies of the three major diffusion mechanisms that simultaneously occur—Knudsen, surface, and activated diffusion. Full article