Search Results (97)

Laurel (Laurus nobilis L.) is a characteristic species of the Mediterranean flora, valued for its medicinal, aromatic, and culinary uses. Many of these properties are attributed to its volatile constituents. In this study, the effect of Atmospheric Room Temperature Plasma (ARTP) pretreatment on laurel powder was evaluated, with emphasis on volatile recovery and food application. Volatile extraction was optimized using headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography–mass spectrometry (GC-MS), investigating key parameters such as salt concentration, extraction temperature, equilibration time, extraction time, and fiber type. Subsequently, critical ARTP variables (nitrogen flow, treatment duration, treatment distance, substrate thickness, and plasma power) were optimized. Response Surface Methodology was applied in both optimization processes. The results demonstrated that fiber type was the most influential factor for volatile recovery, with extraction temperature also exerting a significant effect. A more nuanced pattern emerged during ARTP pretreatment, where moderate plasma intensities enhanced the recovery of several key volatiles. This trend was not uniform across compounds, indicating that plasma-induced microstructural changes interact with the physicochemical properties of individual analytes. To demonstrate food relevance, a ready-to-use broth model prepared with laurel powder confirmed improved headspace transfer of characteristic volatiles following ARTP treatment. Taken together, these findings suggest that ARTP can serve as a practical, non-thermal pretreatment for improving volatile release, supporting its potential use in the food, pharmaceutical, and cosmetic industries. Full article

The scalable production of high-quality nanoparticles is a significant challenge for advancing nanotechnology applications. This research introduces a continuous-flow liquid-plasma discharge reactor for the synthesis of silver nanoparticles at room temperature and atmospheric pressure, utilizing D-xylose as a dual-function reducing and stabilizing agent. The reactor effectively generated uniform xylose-capped silver nanoparticles (X-Ag NPs). Optimal conditions were established utilizing argon gas at a 1:100 molar ratio of Ag precursor to D-xylose, resulting in spherical X-Ag NPs with an average size of 16.89 nm, a zeta potential of −38.87 mV, and a polydispersity index of 0.22. The formation and properties of X-Ag NPs were confirmed through characterization techniques including UV-Vis spectroscopy, dynamic light scattering (DLS), Fourier-transform infrared spectroscopy (FT-IR), and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS). The findings demonstrate that uniform particle nucleation and growth occurred due to the homogeneous distribution of high-energy electrons and reactive gas species produced in the plasma phase. This environmentally sustainable, continuous-flow method shows considerable promise for the industrial-scale production of biomass-derived silver nanoparticles. Full article

The prolonged low temperature in cold regions significantly inhibits the initiation of straw composting and lignocellulose degradation, thereby restricting straw resource utilization. In this study, 24 cellulose-degrading strains capable of stable growth under low-temperature conditions were screened. Based on multiple indicators, including carboxymethyl cellulase (CMCase) activity, strain LDT1 was identified as the best-performing isolate under low-temperature conditions and as Paenarthrobacter nitroguajacolicus. Subsequently, an efficient mutant strain, LDT1-8, was obtained through atmospheric and room-temperature plasma mutagenesis. The CMCase activity of LDT1-8 at 10 °C increased to 74.25 U/mL, representing a 21.72% increase compared to the wild-type strain. In a straw degradation system at 10 °C, LDT1-8 significantly accelerated early-stage degradation kinetics, with straw degradation rates at 3 and 6 d being 72.72% and 38.15% higher than those of the wild-type strain, respectively. Multi-enzyme profiling further indicated enhanced activities of multiple lignocellulose-degrading enzymes at low temperatures, accompanied by a partial shift in the optimal temperature of some enzymes (e.g., laccase) toward lower temperatures. Whole-genome sequencing revealed increased gene numbers related to energy, amino acid, and lipid metabolism in LDT1-8. Comparative genomic analysis suggested that mutations were mainly enriched in regulatory regions, accompanied by local structural variations. Transcriptional analyses further verified the coordinated upregulation of genes involved in cellulose and hemicellulose degradation, cold adaptation, and transcriptional and protein homeostasis processes in LDT1-8. Overall, this study provides an efficient microbial resource and a mechanistic basis for straw bioconversion in cold regions. Full article

Astaxanthin, one of the most commercially valuable carotenoids, is renowned for its potent antioxidant and anti-inflammatory properties and is experiencing growing demand across diverse industries. To enhance astaxanthin production in Paracoccus marcusii, compound mutagenesis was performed using ethyl methanesulfonate (EMS), ultraviolet (UV) radiation, and atmospheric room temperature plasma (ARTP) treatment. Subsequently, a high-throughput microbial microdroplet culture (MMC) system was employed to select fast-growing microdroplet, followed by screening for high astaxanthin-producing mutants on dual-inhibitor plates. The mutant M21 was isolated and exhibited a significant increase of 16.86% in astaxanthin content (1.53 mg/g) and a 19.81% increase in astaxanthin production (11.71 mg/L) compared with the wild type (WT) (p < 0.05). Moreover, the enhanced phenotype of M21 was genetically stable. Response surface methodology (RSM)-based optimization of fermentation conditions further increased astaxanthin content and production to 1.72 mg/g and 12.92 mg/L, respectively, corresponding to improvements of 16.44% and 23.02% over the WT, while simultaneously reducing culture time, total nitrogen requirements, and sodium lactate consumption, thereby lowering production costs. This study achieved significant enhancement of astaxanthin production through novel mutant breeding and fermentation optimization, underscoring the effectiveness of this integrated strategy for application in industrial biotechnology. Full article

Plasma-activated water (PAW) is a liquid enriched with reactive oxygen and nitrogen species (RONS), which impart antimicrobial and bioactive properties. In this study, PAW generated in liquid or gas phase under nitrogen or oxygen atmospheres was characterized in terms of pH, electrical conductivity, oxidation-reduction potential, surface tension, and concentrations of H₂O₂ and NO₂⁻. Hydroxyl radical (•OH) formation was confirmed using DIPPMPO as a spin-trapping probe, while antioxidant activity was determined directly in treated water for the first time. The stability of reactive species was assessed over three months at room temperature, 4 °C, and −18 °C. Results indicate that plasma effects on physicochemical parameters depend strongly on the process gas. From a long-term storage perspective, samples maintained at 4 °C stabilized at higher H₂O₂ and NO₂⁻ concentrations. Antioxidant activity persisted for up to 60 days, though at low levels. EPR analysis revealed that hydroxyl radical concentration increased slightly during storage, with 60-day samples showing higher signal intensities compared to fresh PAW. Overall, the findings provide new insights into PAW composition, radical dynamics, and stability, highlighting the influence of gas atmosphere and storage conditions on its properties and supporting its potential for applications in the food, agriculture, and biomedical sectors. Full article

Esters are predominant fragrance components in various traditional fermented foods. Hongqu rice wine, a beverage gaining popularity among young consumers in China, largely owes its aromatic profile to esterases derived from Monascus species. However, research on esterification characteristics of Monascus strains remains limited, constraining efforts to improve the quality and flavor of Hongqu rice wine. To better understand their esterification characteristics of commercial Monascus strains from different regions of China and further develop a high-quality esterifying Monascus strain for the liquor industry, we identified five Monascus isolates from red koji samples used in rice wine fermentation. Their esterification activity was evaluated by preparing red koji through solid-state fermentation of wheat bran under conditions simulating industrial production. Among the isolates, M. purpureus M21 exhibited the highest reported esterification activity to date, reaching 88.5 ± 8.6 U. Through atmospheric and room-temperature plasma (ARTP) mutagenesis breeding, the esterification activity of M. purpureus M21 was further enhanced by 41% to 124.8 U. In summary, this study not only figures out the properties of commercial esterifying Monascus from diverse regional sources but also significantly enhances the esterification performance of a potent esterifying Monascus strain without invoking GMO controversies. This high-performance esterifying Monascus strain presents a promising fermentation starter to enhance the flavor profile of Hongqu rice wine and diverse fermented beverages, thereby meeting evolving consumer preferences. Full article

The increasing atmospheric CO₂ concentration is one of the major environmental challenges, necessitating not only emission reduction but also effective carbon utilization. Non-thermal plasma-catalytic CO₂ conversion offers an efficient pathway under mild conditions by synergistically combining plasma activation with catalytic surface reactions. In this study, mesoporous ceria catalysts were synthesized by different methods and characterized using N₂ adsorption–desorption, SEM, XRD, XPS, CO₂-TPD, and XRF techniques. The materials exhibited distinct textural and electronic properties, including variations in surface area, pore structure, and basicity. Plasma-catalytic CO₂ dissociation experiments were conducted in a dielectric barrier discharge reactor at near-room temperature. Among the synthesized catalysts, Ce(mp)-4 demonstrated the highest CO₂ conversion of 32.3% at a 5 kV input voltage and superior energy efficiency, which can be attributed to its meso-macroporous structure that promotes microdischarge formation and enhances CO₂ adsorption–desorption dynamics. CO was the only product obtained, with near-100% selectivity. Catalyst stability testing showed no deactivation while spent catalyst characterization indicated carbon-containing species. The findings in this study highlight the critical role of tailored pore structure and basic-site distribution in optimizing plasma-catalytic CO₂ dissociation performance, offering a promising strategy for energy-efficient CO₂ utilization. Full article

Yttria-stabilized zirconia(YSZ) was introduced into the Al₂O₃-TiO₂-CeO₂ coating prepared by plasma spraying to improve the wear resistance of the coating and prolong the service life of the weathering steel. The nano-agglomerated powder was prepared by mechanical ball milling and spray-drying technology, powder was sprayed on the surface of Q355 steel substrate by atmospheric plasma sparing (APS), the Al₂O₃-TiO₂-CeO₂/YSZ composite coating was prepared, and the effects of YSZ on the phase, microstructure, and tribological properties of the composite coating were studied. The results show that nano-agglomerated powders with micron size (average size 55 μm) can be prepared by spray-drying technology, and after high-temperature sintering, the nano-agglomerated powders are denser and form the α-Al₂O₃ phase. The composite coating prepared by plasma spraying has a bimodal structure, and after adding YSZ, the phases in the coating are mainly α-Al₂O₃, γ-Al₂O₃, and t-ZrO₂, the grain size is fine, and the porosity is reduced. The specific wear rate is only 4.4 × 10⁻⁵ mm³ N⁻¹·m⁻¹, the relative wear resistance is 6.3 times higher than that of the substrate, and the wear mechanism of the coating is mainly slight adhesive wear and abrasive wear, which shows excellent friction and wear properties at room temperature. Full article

Over the past few years, naturally sourced bioactive molecules have drawn increased attention for their antioxidant capacity and wide-ranging health effects. At the same time, interest in eco-friendly extraction approaches has risen sharply. Atmospheric Room Temperature Plasma (ARTP), a novel non-thermal pretreatment method, has emerged as a promising green technology due to its minimal environmental impact, cost-effectiveness, and superior extraction efficiency compared to conventional methods. In this study, ARTP pretreatment—optimized across variables such as treatment distance, substrate thickness, power, nitrogen flow, and duration—was combined with ultrasonic-assisted extraction to enhance the recovery of bioactive compounds from Moringa oleifera leaves. Both techniques were optimized using Response Surface Methodology (RSM). Under optimal conditions, the extract yielded a total polyphenol content of approximately 40 mg gallic acid equivalents per gram of dry weight. Antioxidant activity, assessed via ferric-reducing antioxidant power (FRAP) and DPPH radical scavenging assays, reached ~280 and ~113 μmol ascorbic acid equivalents per gram dry weight, respectively, and the ascorbic acid content was ~5.3 mg/g. These findings highlight the potential of ARTP as an effective and sustainable pretreatment method for producing high-value phytochemical extracts, with promising applications in the food, pharmaceutical, and cosmetic industries. Full article

Volvariella volvacea, a fungal species of Volvariella within the Pluteaceae family, is predominantly cultivated in southern China. Polysaccharides, the primary bioactive constituents of V. volvacea, exhibit diverse pharmacological activities. However, current cultivation practices face challenges due to the genetic heterogeneity of strains, leading to inconsistent content and compositional variability of polysaccharides and other functional components. ARTP, denoting atmospheric and room-temperature plasma, is a technology capable of generating plasma jets at ambient pressure with temperatures ranging from 25 to 40 °C. These jets feature high concentrations of highly reactive species, including but not limited to excited-state helium atoms, oxygen atoms, nitrogen atoms, and OH radicals. This study aims to develop high-yielding exopolysaccharide (EPS) strains through integrated ARTP mutagenesis and genome shuffling, thereby overcoming current cultivation bottlenecks. ARTP mutagenesis and genome shuffling significantly boosted EPS production in V. volvacea. ARTP generated nine stable mutants with >20% higher EPS yields. Subsequent genome shuffling (three rounds of protoplast fusion) produced the hybrid strain SL212, which achieved 46.85 g/L of EPS, an 111.67% increase over that of the parent strain under identical conditions. Metabolomics and transcriptomics analyses revealed that differential metabolites and genes were mainly enriched in galactose metabolism, ABC transporter pathways, and the tricarboxylic acid cycle. These pathways enhance monosaccharide biosynthesis and generate ATP, providing both precursors and energy for polysaccharide polymerization, thereby driving EPS overproduction. Preliminary mechanistic analysis identified the key contributing factors driving the elevated polysaccharide biosynthesis. Full article

The increasing demand for sustainable energy has spurred the exploration of advanced technologies for biodiesel production. This paper investigates the use of Dielectric Barrier Discharge (DBD)-generated low-temperature plasmas to enhance the conversion of fatty acid methyl esters (FAMEs) into hydrogenated fatty acid methyl esters (H-FAMEs) and other high-value hydrocarbons. A key mechanistic advance is achieved via in situ distillation: at the reactor temperature, unsaturated C18 and C20 FAMEs remain liquid due to their low melting points, while the corresponding saturated C18:0 and C20:0 FAMEs (with melting points of approximately 37–39 °C and 46–47 °C, respectively) solidify and deposit on a glass substrate. This phase separation continuously exposes fresh unsaturated FAME to the plasma, driving further hydrogenation and thereby delivering high overall conversion efficiency. The non-thermal, energy-efficient nature of DBD plasmas offers a promising alternative to conventional high-pressure, high-temperature methods; here, we evaluate the process efficiency, product selectivity, and scalability of this room-temperature, atmospheric-pressure approach and discuss its potential for sustainable fuel-reforming applications. 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

Erythritol has been widely used in the food industry, which predominantly synthesizes it via microbial fermentation, in which Yarrowia lipolytica serves as the preferred candidate chassis strain. However, the wild-type strain of Y. lipolytica exhibits several limitations, including suboptimal industrial performance and elevated levels of by-products, which pose significant challenges in biomanufacturing processes. It is significant to understand the synthesis mechanism of erythritol for improving the capacity of erythritol production by Y. lipolytica. In this study, a mutant exhibiting high erythritol production and stable genetic performance was obtained via a combination of UV and atmospheric and room-temperature plasma mutagenesis. Some key genes related to erythritol production were identified through comparative transcriptome analysis of the mutant strain, revealing significant changes in their expression levels. Individual overexpression of the genes encoding ribose-5-phosphate isomerase, glucose-6-phosphate-1-epimerase, adenylate kinase, and alcohol dehydrogenase in Y. lipolytica Po1g enhanced erythritol production, demonstrating the critical role of each gene in erythritol production. This finding elucidates the molecular mechanism underlying the improved erythritol yield in the mutant strain. The Y. lipolytica mutant C1 produced 194.47 g/L erythritol in a 10 L fermenter with a productivity of 1.68 g/L/h during batch fermentation, surpassing the wild-type strain and reducing the cultivation time by 21 h. It is significant to understand the mechanism of erythritol synthesis for improving erythritol production and its application in industrial-scale production. Full article

In this study, we established a mutagenesis and high-throughput screening system to select a high-yielding glutathione (GSH)-producing strain of Saccharomyces cerevisiae. The parent strain was mutated by atmospheric and room temperature plasma (ARTP) technology and cultivated using ethionine plate cultivation. Subsequently, high-throughput screening was performed using liquid deep microtiter plates (MTPs) for cultivation and a microplate reader for rapid GSH detection. The results demonstrated the successful selection of a stable mutant strain, S-272, which exhibited significantly enhanced GSH production. Fermentation validation in 5 L bioreactors revealed that S-272 achieved a 14.7% higher final GSH concentration and a 19.5% higher intracellular GSH content compared to the parent strain. The improved performance of S-272 was attributed to enhanced ethanol utilization, elevated activity of γ-glutamylcysteine synthetase (γ-GCS), and increased intracellular trehalose content. This study presents an effective strategy for developing high GSH-yield strains using ARTP complex mutagenesis technology combined with high-throughput screening. Full article