Search Results (363)

This study developed a two-step statistically integrated optimization framework to identify the effects of key fermentation medium components controlling hyaluronic acid (HA) biosynthesis by Streptococcus zooepidemicus. As an initial phase, the Plackett–Burman design was employed to identify the most influential components among yeast extract, casein, peptone, beef extract, MgSO₄·7H₂O, K₂HPO₄, KH₂PO₄, and (NH₄)₂SO₄ by conducting 12 fermentation runs, and 30 g/L of glucose was used as the carbon source. Among the eight ingredients, yeast extract, MgSO₄·7H₂O, and KH₂PO₄ were identified as the most significant factors in enhancing HA production. The following steps were based on the selection of the best carbon and yeast extract sources. Sucrose was selected as the optimal carbon source among glucose and lactose, and Tastone 900-Baker’s yeast extract was selected as the optimal nitrogen source among various yeast extract sources. The final phase of the optimization procedure employed the Box–Behnken design to determine the optimal concentrations of three ingredients: yeast extract (10–30 g/L), MgSO₄·7H₂O (0.2–2.0 g/L), and KH₂PO₄ (1–4 g/L). The results depicted that the optimized media formulation, composed of 30.0 g/L of yeast extract, 1.16 g/L of MgSO₄·7H₂O, and 4.0 g/L of KH₂PO₄, enhanced HA production and biomass OD600 to 545.9 mg/L with 1250–1500 kDa and 2.53 OD600 in a 250 mL shake flask scale, which was around a 10-fold increase in HA production compared with run #10 of Plackett–Burman (57.42 mg/L). This study provided preliminary results for future process conditions optimization, scale-up studies, and techno-economic evaluation. Full article

This study evaluates the development of Halomonas bluephagenesis TD01 as a novel, sustainable microbial platform for the production of hyaluronic acid (HA). Three distinct hyaluronan synthase genes (sezHasA and spHasA—Class I from the Streptococcal group—and pmHasA) were heterologously expressed and compared, with the Class II synthase from Pasteurella multocida (pmHasA) emerging as the superior variant in rich media 60-LBG, achieving significantly higher titers of 0.88 g/L and molecular weight (M_w) of 1.15 MDa (Mega Daltons). Using a combination of Plackett–Burman design and Response Surface Methodology (RSM), the fermentation process was optimized, identifying initial pH, nitrogen source, and NaCl concentration as critical factors. These optimizations led to a maximum HA yield from 0.88 to 2.38 g/L (265% improvement) and M_w from 1.15 to 9.67 MDa. Furthermore, the study demonstrates precise tuning of HA molecular weight, ranging from 2.04 MDa to 9.67 MDa in a modified medium (40LBG-Y), by modulating L-arabinose induction levels. The structural integrity of the purified HA was confirmed via ESI-MS and ¹H-NMR. These findings establish H. bluephagenesis TD01 as a robust Next-Generation Industrial Biotechnology (NGIB) chassis for the scalable and customizable production of HA with a minimal cost and high-molecular-weight HA for medical applications. Full article

Nowadays, approximately 50% of chemical surfactants come from petrochemical sources and pose environmental risks due to poor biodegradability, affecting microbial communities, aquatic organisms, and terrestrial ecosystems. Biosurfactants are eco-friendly alternatives, thanks to their strong surface tension-reducing activity, stability, low toxicity, and biodegradability, but their large-scale production is still limited by high costs and low yields. In this study, rice husk was evaluated as a renewable substrate from the agro-industrial field for lipopeptide production by the endophytic Bacillus subtilis AC7. Medium optimization through Plackett–Burman designs identified nitrogen sources and pH 6.5 as key factors enhancing biosurfactant production. Under optimized conditions, surfactin production increased from 4.2 mg/L in untreated rice husk to 266–276 mg/L with NaNO₃ and NH₄NO₃ supplementation, respectively. Combined laccase–amylolytic pretreatment further improved substrate utilization, enhancing sugar availability and supporting higher biomass and metabolic activity. In bench-scale fermentation, this condition yielded the highest surfactin concentration (237.5 mg/L). LC-MS/MS analysis confirmed surfactin as the main product, with C15 as the dominant homologue, in both shake-flask and bench-scale fermentations. These findings highlight a novel, sustainable process for surfactin production, offering a renewable alternative to synthetic surfactants while addressing both environmental and economic concerns. Full article

Accurate discrete element method (DEM) simulations are essential for elucidating the precision seeding mechanisms and collision damage characteristics of cassava seed stem (CSS); however, such simulations are often limited by a lack of precise contact parameters. In this study, “Guire No. 7” CSS was selected as the research object to calibrate discrete element (DE) parameters by integrating physical experiments with DEM simulations. A stem model was constructed in EDEM software (Altair EDEM 2022) using three-dimensional scanning technology combined with SolidWorks 2024 modeling functions to investigate the influence of the model’s mesh face count on simulation accuracy. Physical experiments measured the average repose angle (RA) of the stems (30.28° ± 1.09°), along with parameters including the restitution coefficient for stem-stem and stem-steel plate collisions, and the coefficient of static friction between the stem and steel plate. The Plackett-Burman Design experiment was employed to screen parameters affecting the RA, and the steepest ascent experiment was conducted to determine their optimal value ranges. Using the RA as the response value, a Central Composite Design experiment combined with machine learning regression models was applied to optimize the influencing parameters and compare model performance. The results indicated that the GA-BP algorithm exhibited superior predictive capability compared to Support Vector Regression (SVR) and the BP neural network. Through optimization using a genetic algorithm (GA), the calibrated parameters were obtained: a stem-steel plate static friction coefficient (SFC) of 0.488, a stem-stem SFC of 0.489, and a stem-stem rolling friction coefficient of 0.131. The resulting simulated RA was 30.73°, yielding a relative error of 1.49% compared to the physically measured value. The GA-BP-GA method demonstrated better optimization performance than the central composite design experiment, thereby validating the accuracy of the calibrated contact parameters between stems. Furthermore, parameters for the Tavares model were calibrated through physical experiments on CSS, using collision damage force and collision damage energy (CDE) as validation indicators. The results showed that the relative errors for both collision damage force and CDE were less than 3%, which is within the acceptable error range, thereby confirming the validity of the calibrated DE parameters for the cassava seed stem. Full article

To address soil degradation and pest accumulation in facility agriculture, this study developed an in situ soil-turning plow for deep soil inversion under spatially constrained greenhouse conditions. A reference plow surface was obtained by reverse engineering, and the final in situ plow surface was reconstructed using plow-body forming theory and a constrained soil-turning trajectory. Soil contact parameters were calibrated in EDEM using the measured soil moisture content and angle of repose. An in situ furrow soil retention rate was proposed to evaluate the proportion of disturbed soil remaining within or returning to the original furrow region. Plackett–Burman screening identified plowing width, plow-body installation angle, and soil-cutting angle as the main factors affecting the retention rate. Box–Behnken optimization yielded optimal values of 278.392 mm, 40.522°, and 23.211°, respectively, with a predicted retention rate of 81.166%. Physical validation showed a 3.13% relative error between predicted and measured values. The optimized plow provides a design reference for compact deep-tillage machinery in greenhouses where lateral soil displacement must be minimized. Full article

The modeling accuracy of rice straw remains limited, and discrete element method (DEM) simulations of its compression are computationally intensive. To address these challenges, this study systematically investigated the physical characteristics of rice straw and proposed an innovative DEM and parameter calibration approach. Uniaxial compression tests were conducted on individual straw stalks, and key DEM parameters were systematically calibrated using Plackett–Burman experiments, steepest ascent trials, and Central Composite design. The calibrated parameters were validated against single-straw compression tests, showing a relative error of only 1.9% between simulated and measured peak loads, indicating high model fidelity. Building on this foundation, vibration-assisted compression bench tests were performed on bulk straw, further validating the scaled-up DEM and its parameters. The evolution of normal forces and porosity during compression was analyzed by comparing experimental results with simulations, confirming the model’s accuracy in capturing straw compaction behavior. Finally, a comparison of computational efficiency between the scaled-up and original DEMs revealed that the scaled-up model reduced computation time by approximately 67.4% and 65.2%, respectively, significantly improving simulation efficiency. This study provides a robust methodology for modeling flexible agricultural fibers and establishes a foundation for efficient numerical simulation of straw compression. Full article

Twenty strains of Schizophyllum commune from the BIOTEC culture collection were selected for this study. S. commune is characterized by white to gray fan-shaped caps with lobed margins and distinctive split gills. Phylogenetic analysis of combined LSU rDNA and ITS rDNA sequences data using maximum parsimony placed the fungi in a strongly supported clade with S. commune. All strains were primarily screened for exopolysaccharide (EPS) and biomass production using potato dextrose broth (PDB) and peptone yeast glucose medium (PYGM) in 250 mL flasks shaken at 200 rpm for 7 days. The results revealed three strains with high EPS production, each exceeding 2.3 g/L, namely MMCR00487, MMCR00474 and MMCR00256. These strains were selected for media optimization using a Plackett–Burman design. Among them, MMCR00256 exhibited the highest EPS yield of 8.34 ± 1.47 g/L, followed by MMCR00487 and MMCR00474. Therefore, the strain MMCR00256 was further optimized by central composite design. The results revealed that the optimized medium for MMCR00256 increased the production of EPS to 10.39 ± 1.69 g/L, with a biomass yield of 26.28 ± 1.63 g/L (395 mg/g). The 5 L bioreactor optimization tested two inoculum types (mycelial and pellet) and two media (CCD and estimated) using strain MMCR00256. The mycelial inoculum grown in the estimated medium produced the highest EPS yield of 8.37 ± 0.26 g/L after 3 days, with 13.56 ± 2.94 g/L biomass. In conclusion, this study demonstrates that S. commune MMCR00256, when cultivated using the estimated medium and mycelial inoculum, can achieve enhanced exopolysaccharide production with improved efficiency, highlighting its significant potential for the development of efficient and scalable schizophyllan production processes at the industrial scale. Furthermore, this study provides essential insights into the cultivation and optimization of schizophyllan in S. commune. Full article

The discrete element method (DEM) is widely used to simulate concrete failure, but calibrating its mesoscopic dynamic parameters is computationally expensive due to the high-dimensional parameter space. This study proposes a physics-informed active learning framework to autonomously calibrate these parameters under impact loads. An FDM-DEM coupled split Hopkinson pressure bar model is established to simulate macroscopic dynamic compressive responses. Subsequently, a Plackett–Burman experimental design reduces the parameter optimization space from 16 to 8 core dimensions. A multi-layer perceptron surrogate model is then constructed. By comparing two heuristic active sampling strategies, results indicate that a parameter priority-guided strategy incorporating physical priors significantly outperforms a mid-value exploration strategy. The proposed approach achieves coefficients of determination exceeding 0.9 for predicting multiple macroscopic dynamic indicators on an independent testing set. Building upon this forward mapping, a robust inverse parameter prediction mechanism is established, achieving a closed-loop reconstruction of 0.8662. This framework provides a reliable, data-efficient, and automated pathway for calibrating complex multiphase particulate systems. Full article

Rabbit manure with high-moisture content exhibits complex adhesive and flow behaviors, which make accurate parameterization in discrete element method (DEM) simulations difficult. To improve the reliability of DEM modeling for rabbit manure composting processes, this study calibrated the contact parameters of rabbit manure at 65% moisture content using the angle of repose as the target response. A physical angle of repose test was first conducted using the cylindrical lifting method, yielding a measured value of 38.77°. The Hertz–Mindlin with Johnson–Kendall–Roberts (JKR) contact model was then adopted to represent the adhesive behavior of the material, and a three-stage optimization strategy consisting of a Plackett–Burman screening test, a steepest ascent test, and a Box–Behnken design was applied to identify and optimize the key parameters. The results showed that the particle restitution coefficient, rabbit manure–PLA rolling friction coefficient, and surface energy were the dominant factors affecting the angle of repose. The optimal parameter combination was a particle restitution coefficient of 0.56, a rabbit manure–PLA rolling friction coefficient of 0.375, and a surface energy of 0.243 J/m². Under these conditions, the simulated angle of repose was 39.21°, with a relative error of 1.13%. These calibrated parameters provide a reliable basis for DEM simulation and engineering optimization of rabbit manure composting equipment. Full article

Sugarcane is an important economic crop in southern China. Affected by typhoons, it is prone to lodging, which not only increases the difficulty and loss rate of mechanical harvesting but also reduces the sugar content. The mechanical properties of the sugarcane root–soil system are crucial to its lodging resistance. However, accurate discrete element parameters are still lacking for DEM-based research on the mechanical properties of this system. Therefore, this study adopts a method combining the angle of repose test, shear force test, and discrete element simulation of single roots to calibrate DEM parameters. Using the angle of repose and maximum shear force of a single root as response values, Plackett–Burman, steepest ascent, and Box–Behnken tests are sequentially carried out with Design-Expert 13 software to calibrate the contact and bonding parameters of individual sugarcane roots. The relative errors between the physical and simulation test results for the angle of repose and shear force are 1.29% and 0.66%, respectively. This study provides a reference for the establishment of discrete element simulation models for sugarcane roots and for the subsequent development of sugarcane root–soil composite models. Full article

Green-synthesized silver nanoparticles (AgNPs) exhibit outstanding antibacterial and antioxidant potential for designing and developing nanomedicines and medical devices. Nephelium lappaceum or rambutan contains polyphenol-based phytochemicals, which suggests its suitability for the green synthesis of NPs. However, the lack of a systematic approach directly impacts the robustness and reproducibility of the process. Design of experiments can address these challenges in obtaining NPs with the desired quality profile. In this work, we demonstrated the advantages of a Plackett–Burman model in the semi-automated green synthesis of AgNPs using N. lappaceum peel extract. The extract concentration was the only significant factor affecting the particle size. The optimized NPs exhibited triangular and hexagonal morphologies and a hydrodynamic diameter of 80 nm after 24 h without a stabilizing agent, representing 1.2% prediction error according to the model’s equation. The in vitro antioxidant capacity was confirmed through the ABTS radical scavenging assay. The AgNPs displayed a minimum inhibitory concentration of 23.5 µg mL⁻¹ against Escherichia coli and Staphylococcus aureus. Overall, this work highlights the synergistic role between a DoE-assisted green synthesis, the phytochemicals from N. lappaceum peel extract, and the formed AgNPs, positioning this systematic approach as a sustainable and efficient process for novel antibacterial and antioxidant agents. Full article

Solid-state fermentation (SSF) is a long-established biotechnological approach gaining renewed interest for its ability to enhance nutrient availability and improve the functional properties of agro-industrial by-products. This strategy is particularly relevant for early post-weaning piglets, which are highly susceptible to weaning stress due to an immature digestive system and a gut microbiota not yet adapted to solid feed. In this study, the fermentation parameters of flaxseed cake were optimized using a Plackett–Burman experimental design. Protease activity was selected as the response variable due to its relevance for improving protein degradation and potential digestibility in fermented feed ingredients. Accordingly, based on the statistical analysis, the conditions selected for the in vivo trial were 1% molasses, 0.5% yeast extract, 0.05% CaCl₂, 0.5% NaCl, 7.5% inoculum (4.12 × 10⁹ CFU/mL), 60% moisture, and 72 h fermentation. Fermentation time was identified as the main factor positively influencing protease production, while higher CaCl₂ concentrations and inoculum levels negatively affected enzyme activity. Optimization increased protease activity, microbial viability and free amino acid content. In addition, SSF reorganizes the carbohydrate profile by reducing structural fiber fractions, with neutral detergent fiber and acid detergent fiber decreasing by 27% and 29%, respectively, while simultaneously increasing soluble carbohydrates by 14.67%. Phytic acid content being also reduced by 23.81%. A pilot nutritional trial on post-weaned piglets (35 days old) showed that including 8% fermented flaxseed cakes (FFSC group) improved body weight, average daily gain, feed conversion ratio, and diarrhea score, without affecting average daily feed intake, compared with 8% unfermented flaxseed cakes (FSC group). These performance improvements were accompanied by changes in fermentation metabolites and gut microbial composition. Lower isovalerate concentrations suggested reduced proteolysis, while higher propionate levels may contribute to increased blood glucose availability in the FFSC group. These changes coincided with a shift in microbial composition, characterized by a reduced abundance of methanogenic archaea and increased abundances of taxa such as Lactobacillus, Enterococcus, and members of the Lachnospiraceae and Eubacteriaceae families. Full article

The endosperm of Gleditsia japonica var. delavayi seeds is a valued medicinal and edible material, rich in polysaccharides exhibiting excellent functional properties for food applications. However, conventional methods for extracting Gleditsia japonica var. delavayi polysaccharides (GJP) are often inefficient and environmentally unfriendly. Thus, we developed a green, ultrasound-assisted process for extracting GJP. We systematically optimized key parameters (liquid-solid ratio and ultrasonic time, temperature, and power) using single-factor, Plackett–Burman and Box–Behnken experimental designs to maximize yield and characterize the product. The optimized process (200 mL/g, 62 min, 51 °C and 180 W) exhibited an extraction yield of 76.11%, producing GJP with a purity of 79.89%, which satisfies standards for food additives. The extracted GJP exhibited a semi-crystalline structure, high solubility (80.06%), low esterification degree (2.60%) and high viscosity and thermal stability between 30 °C and 70 °C. Crucially, this process required no chemical reagents and consumed only 0.18 kW·h of energy. Analysis indicates that the optimized ultrasound-assisted extraction of GJP is a green and efficient method with high extraction rates and reduced processing time and energy consumption; furthermore, it does not require any chemical reagents, making it a promising alternative to conventional techniques. Full article

Industrial spore production of the probiotic Heyndrickxia coagulans is hindered by its generally low and highly variable sporulation efficiency across strains. To address this, we selected the representative model strain ATCC 7050 and applied an integrated strategy combining statistical medium optimization with genomic analysis. Key factors (glucose, yeast extract, CaCl₂) were screened and optimized using Plackett–Burman and Box–Behnken designs, yielding an optimal formulation that achieved 1.84 × 10⁸ spores/mL in a bioreactor, consistent with the model prediction. Further genomic analysis revealed 112 sporulation-associated genes and identified key homologous genes related to spore resistance and germination. Among them, the successful identification of spoVA, which is implicated in calcium-dipicolinate transport in bacilli, allowed us to hypothesize why calcium ions play a critical role. This work not only enhances the spore yield of a model strain but also provides a framework to tackle the widespread sporulation variability in H. coagulans for industrial applications. Full article

Moisture content varies continuously during aerobic composting, which changes material flowability and can limit the use of a single set of discrete element method (DEM) parameters. To address this issue for a multi-component corn straw–pig manure mixture, we developed a rapid calibration workflow covering a moisture content range of 29–80%. Angle of repose (AoR) images were obtained using a cylinder-lifting test. To improve robustness for irregular pile contours, we proposed an AoR extraction method that combines LOESS smoothing with least-squares line fitting. Key DEM contact parameters affecting AoR were screened using a Plackett–Burman design, and their effective ranges were refined using a steepest-ascent test. A Box–Behnken design was then used to establish a response surface linking AoR to the significant DEM parameters. In addition, a polynomial relationship between moisture content and AoR was fitted and coupled with the AoR-parameter response surface to predict key DEM parameters directly from moisture content. Validation results showed that the predicted AoR exhibited a relative error below 10% across the tested moisture contents. An independent baffle-lifting validation test yielded a relative error below 5%. Overall, this workflow provided a practical strategy for setting DEM simulations of composting feedstocks under variable moisture content and supports numerical analysis and structural optimization of composting-related machinery. Full article