Search Results (622)

β-Galactosidase is an important enzyme for lactose hydrolysis because it catalyzes the conversion of lactose into glucose and galactose. In this study, Aspergillus niger C18, which showed β-galactosidase-producing ability during preliminary screening, was selected as the gene source. A β-galactosidase gene from this strain was cloned into the pET28a vector and heterologously expressed in Escherichia coli. Solid-state fermentation conditions were optimized to produce the native enzyme as a reference for comparison. The enzymatic properties of the recombinant enzyme were then systematically characterized and compared with those of the native enzyme. The recombinant β-galactosidase exhibited favorable thermal and pH stability. After incubation for 2 h at its optimal pH and optimal temperature, the recombinant enzyme retained 88.9% and 94.1% of its initial activity, respectively; specifically, 88.9% corresponded to pH stability and 94.1% corresponded to thermal stability. These results indicate favorable stability of the recombinant enzyme under the tested conditions. Thin-layer chromatography and high-performance liquid chromatography analyses confirmed that the recombinant enzyme efficiently hydrolyzed lactose in a model lactose solution, achieving more than 99.0% lactose degradation after 12 h of reaction. These findings suggest that β-galactosidase derived from A. niger C18 is a promising candidate for lactose hydrolysis. Full article

Cobalt occupies an irreplaceable strategic position in renewable energy and high-end advanced industries. As high-grade mineral resources gradually deplete, associated sulfide minerals have attracted increasing attention as alternative sources of cobalt. This study investigated a selective extraction of cobalt from low-grade cobalt-bearing pyrite using oxygen-pressure acid leaching. The Gibbs free energy (ΔG) of key chemical reactions in the leaching system was calculated to verify the thermodynamic feasibility of the process. The effects of critical parameters, including oxygen pressure, initial acidity, stirring speed, leaching time, and temperature, on cobalt leaching efficiency and phase transformation characteristics were systematically investigated. Under optimal conditions of oxygen pressure 1.5 MPa, H₂SO₄ initial acidity 7.36 g·L⁻¹ (0.82 mol/L), stirring speed 300 rpm, leaching duration 120 min, and temperature 230 °C, the cobalt leaching rate reached 98.2%, whereas the leaching rates of iron and aluminum were only 19.79% and 28.11%, respectively. Combined with SEM-EDS, XRD, and XPS characterization results, oxygen pressure acid leaching effectively destroyed the lattice structure of cobalt-bearing pyrite and liberates lattice-hosted cobalt, thereby facilitating efficient cobalt leaching. At high-temperature and oxygen pressure conditions, Fe³⁺ underwent hydrolysis and precipitated as hematite (Fe₂O₃) or hydronium jarosite (H₃O)Fe₃(SO₄)₂(OH)₆, enabling the selective extraction of cobalt. Aluminum in cobalt-bearing pyrite primarily occurred as the stable boehmite (AlOOH) phase, exhibiting excellent acid resistance and low dissolution during leaching. This study broadens the utilization pathway of low-grade cobalt resources and provides valuable insights and a scientific theoretical basis for the efficient treatment of cobalt-containing sulfide concentrates and tailings. Full article

The structure, functionality, nutritional value, and sensory properties of food are significantly influenced by interactions between proteins and carbohydrates. These interactions occur through hydrogen bonding, electrostatic forces, hydrophobic interactions, and, in many cases, the covalent attachment of sugars to proteins via the Maillard reaction. High starch content in food matrices promotes interactions between proteins and starch components such as amylose and amylopectin, affecting gelation, retrogradation, and thickening. These interactions improve shelf stability and product quality. Additionally, protein–carbohydrate interactions regulate nutrient digestibility and glycemic response, playing a crucial role in the development of functional foods for diabetes and weight management. In silico studies have demonstrated that dietary fibers like pectin and cellulose can improve water retention and textural properties in processed meat products. Furthermore, processing techniques such as enzymatic hydrolysis, fermentation, pulsed electric fields (PEF), and low-temperature drying have been found to improve the functional properties and shelf life of food products. This review synthesizes recent findings on protein–carbohydrate interactions and highlights their potential in creating healthier, more appealing, and sustainable foods that align with modern consumer preferences. Full article

Gelatin is a valuable hydrocolloid produced by partial hydrolysis of collagen from mainly mammalian and fish sources. The rheological properties of fish gelatin differ from those of mammalian species in terms of gel strength, viscosity, and other rheological characteristics, even from different fish species and parts of the fish with different properties. Fish gelatin is sustainable for the environment and easy for people to accept for cultural reasons. Owing to these properties, gelatin is used across food, biomedical, pharmaceutical, and health sectors, where 3D printing enables customization and functional performance. Key determinants of print fidelity include gelatin concentration, rheological properties, temperature, gelling behavior, water content, and printing parameters. Suitability for 3D printing is typically assessed via physicochemical characterization, particularly rheology and gelling mechanisms/kinetics. Gelatin-based 3D printing systems offer various advantages due to their biocompatibility, low cost, and controllable rheological properties, and they have potential applications in the food, healthcare, biomedical, tissue engineering, and drug delivery system areas. Using gelatin in combination with other additives can improve printing accuracy and mechanical strength parameters, overcome the limitations of gelatin’s inherent mechanical strength, and develop higher printing accuracy and performance systems. This allows for the development of functional, innovative, and high-value-added products while ensuring safe use. Full article

The treatment of high-salinity, low-carbon marine aquaculture wastewater poses significant challenges for biological denitrification. This study systematically evaluated the performance of a polycaprolactone (PCL)-based aerobic denitrification biofilter under varying temperatures (15 °C and 25 °C) and PCL addition levels (282, 564, 846, 1128, and 1410 g). Optimal nitrogen removal, total nitrogen (TN) removal efficiency exceeding 92%, was achieved with 1128 g PCL at 15 °C (HRT 10 h) and 1410 g PCL at 25 °C (HRT 8 h), significantly outperforming the low-PCL baseline treatment. Microbial community analysis revealed that increased PCL dosage promoted the dominance of the hydrolytic genus Flavobacterium over Simplicispira, enhancing polymer degradation capacity and system stability. Metagenomic sequencing further elucidated the complete PCL degradation pathway, wherein hydrolysis products were oxidized to generate NADH and FADH₂, serving as electron donors for denitrification. Key functional genes (narG, nirK, nosZ) and enzymes associated with both PCL decomposition and nitrate reduction were significantly enriched in high-performance reactors (e.g., AT15H6, AT25H6, ET15H10, ET25H10), correlating strongly with observed nitrogen removal rates. By integrating reactor performance with microbial ecology and functional genetics, this work provides a comprehensive “material–microorganism–gene–performance” framework, offering both practical strategies and mechanistic insights for enhancing denitrification in saline aquaculture systems. Full article

Hydrogen-fueled internal combustion engines (H₂-ICEs) impose unique challenges on engine lubrication because water is an inevitable combustion product. This review summarizes the current understanding of water-induced degradation mechanisms in engine oils for H₂-ICEs, with emphasis on physicochemical property variation, additive depletion, tribofilm evolution, and tribological performance. Water present in dissolved, emulsified, or free states can significantly alter lubricant viscosity, destabilize additive systems, and accelerate oxidative aging. In particular, water promotes the depletion of zinc dialkyldithiophosphate (ZDDP) through tribofilm removal and competitive adsorption at rubbing interfaces, while also inducing additive hydrolysis that transforms long-chain phosphates into shorter-chain species with inferior film-forming capability. These processes inhibit tribofilm growth and reduce the mechanical integrity of protective films, thereby deteriorating anti-wear performance. Although substantial progress has been made in understanding the role of liquid water in lubrication, the tribochemical effects of high-temperature water vapor under realistic H₂-ICE operating conditions remain largely unexplored. Future research should therefore focus on water vapor-dominated lubrication environments representative of hydrogen combustion, aiming to elucidate the underlying tribochemical mechanisms and support the development of dedicated lubricants for durable and reliable H₂-ICE operation. Full article

Proteases, enzymes that catalyze the hydrolysis of peptide bonds in peptides and proteins, have widespread industrial applications, particularly in milk coagulation for cheese production. Microbial enzymes have been employed as alternatives to animal rennet, offering advantages such as cost-effectiveness, availability, and compliance with dietary, cultural, and religious requirements. Solid-state fermentation (SSF) is widely employed for microbial enzyme production because of its low operational costs, reduced water and energy requirements, high product concentrations, and the ability to utilize agro-industrial residues as low-cost substrates, thereby contributing to both process sustainability and waste valorization. We report the production and characterization of a novel milk-clotting protease produced by Trichoderma koningii FFT13. The protease was produced by SSF using wheat bran as the substrate, an agro-industrial residue. It was classified as a chymotrypsin-like serine protease and exhibited a specific caseinolytic activity of 9861 U/mg. The enzyme coagulated both reconstituted skim milk and pasteurized whole milk in the presence or absence of calcium. Coagulation was enhanced by increasing temperature, reaction time, enzyme concentration, and calcium levels. Scanning electron microscopy revealed destabilization of casein micelles, their progressive aggregation, and the formation of a well-defined gel network, confirming the effectiveness of the protease in milk coagulation. Therefore, these results demonstrate that the chymotrypsin-like protease from T. koningii is a promising enzyme for milk coagulation, with potential application in cheese production. The enzyme obtained constitutes an alternative to traditional coagulants, overcoming limitations related to animal rennet while potentially offering additional advantages in terms of process sustainability and industrial scalability. Full article

Hemp seed protein hydrolysate (HSPH), despite its high digestibility and solubility, exhibits severely impaired gelation properties due to extensive hydrolysis, thereby limiting its food applications. This study analyzed the effect of homogeneously incorporating commercial hemp seed protein concentrate (HSPC) into HSPH on physicochemical and structural properties of the resultant composite gels. As the HSPC concentration increased from 100 to 150 mg/mL, the composite gels exhibited a significant enhancement in hardness (p < 0.05), increasing from 1.63 to 5.74 N, along with an improvement in water-holding capacity (WHC) from 45.52 to 55.46 g/g. Concurrently, the storage modulus (G′) and gelation temperature increased, with the latter rising from 65 to 78 °C. SDS-PAGE analysis suggested that the enhanced composite gel properties were attributed to its high-molecular-weight protein fractions (10–15 kDa and 40–50 kDa) of HSPC, which functioned as the primary structural components of the gel network. In addition, the formation of denser yet irregular microstructures was observed by scanning electron microscopy (SEM) analysis when HSPC incorporation increased from 0 to 200 mg/mL. Fourier-transform infrared (FTIR) further suggested that these improvements were due to increases in β-turn and random coil contents by approximately 9.60 and 7.73%, respectively. These findings provided insights into the utilization of HSPH and HSPC in plant-based foods and contributed to food security and sustainable agriculture. Full article

Starch-degrading enzymes are key biocatalysts in industrial applications, particularly when derived from thermophilic microorganisms with potential to operate under elevated temperatures. In this study, three recombinant starch-degrading enzymes were heterologously produced, purified, and biochemically characterized: an α-amylase from Geobacillus kaustophilus, and an α-glucosidase and a type I pullulanase from Geobacillus sp. G4, a thermophilic strain isolated from a geothermal field in southern Peru. The three enzymes were successfully expressed in soluble form in Escherichia coli and purified by one-step affinity chromatography. Biochemical characterization showed that α-glucosidase and α-amylase displayed optimum activity at pH 6–7, whereas pullulanase exhibited a broader pH profile, retaining high activity up to pH 9. All three enzymes reached maximum activity at 60 °C, although their thermal stability profiles differed markedly, with pullulanase showing the highest thermostability. Metal ion assays revealed enzyme-dependent effects, with pullulanase being stimulated by Ca²⁺ and Mg²⁺, while α-amylase and α-glucosidase showed limited responses to divalent ions. Kinetic analysis using soluble potato starch indicated that α-amylase had the most favorable catalytic profile, with the lowest K_m and the highest catalytic efficiency among the three enzymes. Functional hydrolysis assays demonstrated that all enzymes were active on soluble starch and pretreated potato peel, while the enzymatic mixture consistently released the highest concentration of reducing sugars. These results expand the biochemical knowledge of thermophilic amylolytic enzymes from Geobacillus and support their potential use in future enzymatic systems for the conversion of starch-rich residues. Full article

Neutralization residue results from the hydrometallurgical extraction of magnesium in serpentine, and contains abundant Fe³⁺, Mg²⁺, and Al³⁺. The recovery of these metals involves acid leaching and precipitation. Fe³⁺ often causes co-precipitation and makes separation difficult. The reduction of Fe³⁺ into Fe²⁺ can separate iron from other metals. The reduction kinetics of Fe³⁺ by SO₂ in the acidic leachate from the neutralization residue was studied systematically within the temperature range of 323 to 363 K. The results indicate that SO₂ reduction follows first-order kinetics with respect to Fe³⁺ and 0.71-order with respect to SO₂. SO₂ reduction undergoes dissolution, hydrolysis, complex and reduction. SO₂ dissolution is an exothermic process with ΔH_sol = −42.88 kJ mol⁻¹, the reduction step has an activation energy of 14.52 kJ mol⁻¹. The reduction process is controlled by dissolution and hydrolysis. High pH accelerate the reduction while the co-existing Al³⁺, Mg²⁺ and Ni²⁺ ions inhibit the reduction. A multi-factor-controlled kinetic equation for the reduction of Fe³⁺ by SO₂ was built. This study provides a reference for the establishment of a multi-factor control system dynamics model. Full article

Consolidated bioprocessing (CBP), in which enzyme production, substrate hydrolysis, and fermentation occur in a single bioreactor, offers a promising pathway for lignocellulosic ethanol production. However, CBP operation involves competing objectives, including ethanol titer, volumetric productivity, substrate conversion, soluble sugar accumulation, batch duration, control effort, and the operating severity associated with temperature and pH profiles. This study introduces a feasibility-aware multi-objective dynamic optimization framework for identifying Pareto-optimal operating policies for batch CBP. A reduced-order mechanistic model is developed to represent biomass growth, enzyme activity, insoluble substrate hydrolysis, soluble sugar formation and consumption, ethanol production, and inhibition under time-varying temperature and pH conditions. The optimization simultaneously maximizes ethanol titer, productivity, and substrate conversion while minimizing sugar accumulation, operating severity, control movement, and batch time. In the main simulation run, 120,000 dynamic policies were retained for analysis, resulting in 5017 feasible policies and 328 feasible Pareto-optimal policies under a minimum conversion threshold of 0.42. Within the feasible Pareto archive, the highest ethanol titer reached $1.265\mathrm{g}{\mathrm{L}}^{-1}$, the highest productivity reached $0.017\mathrm{g}{\mathrm{L}}^{-1}{\mathrm{h}}^{-1}$, and the maximum conversion reached 0.440. Compared with the best criterion-specific static constant-operation baselines, the dynamic Pareto policies improved ethanol titer, productivity, and conversion by 10.6%, 8.3%, and 14.3%, respectively. A feasibility analysis showed that a conversion threshold of 0.42 was stringent but attainable, whereas thresholds of 0.44 and 0.55 were not attainable under the present model and operating bounds. Independent-seed repetitions confirmed a consistent high-performing region across stochastic searches. The resulting Pareto fronts and operating policy maps provide a model-based decision-support basis for selecting dynamic temperature and pH profiles for CBP operation. Because this study is in silico, future experimental validation is required before direct pilot- or industrial-scale application. Full article

Marine by-products represent a promising source of bioactive peptides. This study aimed to isolate and characterize a low-molecular-weight peptide fraction with antioxidant activity from Argentine shortfin squid carcass by-products, and to evaluate in vitro its cytocompatibility and protective effects against corticosterone (CORT)-induced oxidative injury in rat adrenal pheochromocytoma (PC12) cells and human astrocyte (hACs) cells. Argentine squid antioxidant peptide (PASN) was obtained by size-exclusion chromatography and fractionation-based screening. PASN exhibited the strongest overall free-radical-scavenging activity and consisted predominantly of components below 1 kDa (211.73–1013.48 Da). Spectroscopic analyses indicated that enzymatic hydrolysis transformed its structure from a rigid triple-helix conformation to a more flexible conformation dominated by β-turns (50.78%) and random coils (17.38%). In addition, thermogravimetric analysis confirmed its excellent thermal stability, with an onset decomposition temperature as high as 244.81 °C, supporting its potential applicability in high-temperature food-processing matrices. In vitro assays demonstrated that PASN exhibited high biocompatibility and promoted proliferation of both PC12 cells and hACs, while significantly improving cell viability under CORT challenge. PASN also reduced lactate dehydrogenase (LDH) leakage (hACs: 38.31%; PC12: 31.17%) in both cell models and restored total superoxide dismutase (T-SOD) activity (hACs: 69.46%, PC12: 66.40%). Immunofluorescence further revealed that PASN rescued the expression of brain-derived neurotrophic factor (BDNF) (hACs: 35.23%, PC12: 12.50%) and glutamate decarboxylase (GAD1/2) (hACs: 102.66%, PC12: 31.31%), key markers associated with synaptic plasticity and GABAergic sleep regulation. Collectively, PASN is a thermally stable squid-derived peptide fraction that exerts antioxidant and cytoprotective effects in neural cell models in vitro and represents a promising sustainable candidate for nutraceutical development. Full article

The degradation of mulch materials in perennial cropping systems is governed by both polymer properties and environmental conditions. Their relative influence under field conditions remains unclear. To our knowledge, this study is one of the first to integrate mass loss measurements, polymer characterization, and soil microclimatic assessment under field conditions. A one-year field experiment was conducted under irrigated Mediterranean conditions to compare the degradation of Kraft^® paper and polybutylene adipate terephthalate (PBAT)-based (Kritifil^®) mulch with polypropylene (PP) geotextile fabric and polyethylene (PE) mulch in randomized blocks, with three replicates. Mass loss was quantified in situ using mesh bags, while soil moisture, temperature, and electrical conductivity (EC) were monitored monthly to characterize microclimatic and edaphic conditions underlying mulch treatments. Polymer changes were assessed by ATR-FTIR analysis of field-exposed mulch fragments. Kraft^® paper degraded rapidly (≈72% mass loss), consistent with moisture-driven biological processes and susceptibility to hydrolysis. In contrast, PBAT-based mulch showed limited degradation (≈3.5%) despite favourable conditions, suggesting constraints in enzymatic activity. No mass loss was observed for PE- and PP-based mulch. ATR-FTIR analysis indicated minimal structural changes in PBAT, PP, and PE, reflecting their high stability. Overall, polymer composition and inherent (bio)degradability, rather than soil thermal time, were the main drivers of mulch (bio)degradation under Mediterranean conditions. Full article

This study investigates the extraction of perilla seed oil using an ultrasound–ethanol pretreatment combined with aqueous enzymatic extraction (UEAEE). By comparing different pretreatment groups, it was found that the combination of ultrasound and ethanol pretreatment yielded the highest oil extraction efficiency from perilla seeds. Meanwhile, scanning electron microscopy (SEM) analysis further revealed pronounced structural disruption in seeds subjected to ultrasound–ethanol pretreatment, including extensive cellular collapse and the formation of numerous irregular pores and fissures, which facilitated subsequent oil release. The parameters of aqueous enzymatic extraction (AEE) were optimized using a Box–Behnken design. The optimal conditions were determined to be a hydrolysis time of 5 h, a reaction temperature of 52 °C, an enzyme concentration of 5%, and a liquid-to-material ratio of 9.5:1 (mL/g). Compared with oils obtained by pressing extraction (PE) and Soxhlet extraction (SE), UEAEE-derived oil exhibited a higher proportion of unsaturated fatty acids, along with lower peroxide and Acid value (AV), indicating superior quality and a reduced susceptibility to rancidity. Moreover, UEAEE oil retained markedly higher levels of micronutrients (carotenoids: 1.23 mg/kg; total flavonoids: 1.04 mg/g; total phenols: 2.79 mg/g) and demonstrated stronger antioxidant activity (DPPH: 80.60%). Overall, these results demonstrate that UEAEE is an efficient and environmentally friendly extraction method that supports the high-value utilization of perilla seed oil and aligns with modern green processing principles. Full article

Polylactic acid (PLA), a biodegradable polymer derived from renewable resources, represents a promising candidate for sustainable textiles. Nevertheless, its practical application remains limited by the requirement for high-temperature dyeing, which can induce polymer hydrolysis and lead to the loss of fiber strength. To address this limitation, PLA fabric was treated with an eco-friendly natural deep eutectic solvent (NaDES) composed of glycerol and citric acid. The treatment was found to enhance fiber surface roughness and internal looseness, which facilitated dye diffusion and allowed for a significant reduction in dyeing temperature. When dyed with microbial prodigiosin, the treated PLA fabric achieved a color depth at 70 °C that was equivalent to untreated fabric at 90 °C, while also exhibiting a 93.56% bacteriostatic rate against Staphylococcus aureus due to the inherent antibacterial property of microbial prodigiosin. This work provides a novel and sustainable strategy for the eco-friendly dyeing of PLA textiles. Full article