Box-Behnken Response Surface Method Research Articles

Enhanced pectinase production by optimizing fermentation conditions of Bacillus subtilis growing on hazelnut shell hydrolyzate

This study describes optimization of polygalacturonase (PG) production using Bacillus subtilis in submerged fermentation by Plackett–Burman (PB) design and response surface methodology (RSM). Five variables (pH, time, temperature, yeast extract concentration and K2HPO4), which were determined to be significant by the PB analysis, were further optimized using Box–Behnken response surface method. The optimization results indicated that a maximal PG activity of 5.60UmL−1 was achieved at pH 7.0, 72h, and 30°C using 0.5% (w/v) yeast extract and 0.02% (w/v) K2HPO4 in the fermentation medium. The results implied a 2.7-fold increase in PG activity of B. subtilis under the optimized conditions. Thus, it was concluded that hazelnut shell hydrolyzate have remarkable potential for low cost commercial PG production.

Optimization of the Adsorption Condition for Wastewater Containing Chromium Treatment by Natural Adsorbent Material Using Response Surface Methodology

The effect of several important parameters on the removal of hexavalent chromium by humic acid was evaluated using an optimal experimental design based on Box-Behnken Response Surface method. The factors included temperature、pH、initial potassium chromate concentration and adsorbent dosage. A quadratic model for predicting the optimum removal conditions was derived, and the obtained optimal parameters were temperature 51°C, pH=2.34, initial potassium chromate concentration 14.30mg/L and adsorbent 0.58g. At the optimal conditions, the maximal removal rate of hexavalent chromium reached 73.17 %( forecast value was 73.26%).

Optmization for cutting procedure of Astragali Radix with Box-Behnken design and response surface method

Astragali Radix was firstly recorded in the "Shen Nong's Herbal Classic" as a top-grade and commonly used traditional Chinese medicine. Its frequently used slices include raw Astragali Radix and honey-processed products. In current studies, many reports were made on honey-processed Astragali Radix, whereas fewer study reports were made on the cutting process of Astragali Radix. Currently, because Astragali Radix is primarily cut by drug workers according to their operating experience, but with out specific cutting parameters, it is easy to cause the loss or mildew of active ingredients. As a result, the quality of Astragali Radix circulated in the market is not guaranteed, and the quality of their slices and preparations are hard to be controlled, which seriously impact the clinical efficacy. In response, this experiment was performed, in which the optimum cutting process of Astragali Radix was taken as the study objective, the Box-Benhnken central composite design in the response surface analysis was adopted, and the content and appearance character of astragaloside and calycosin-7-glucoside were regarded as the study indicators. Three factors, namely the softening time, the drying temperature and the drying time, were selected to optimize the cutting process of Astragali Radix and obtain the optimum cutting process parameters as follows: the softening time was 3 hours, the drying temperature was 50 degrees C, and the drying time was 4 hours. According to the verification test, the Astragali Radix cutting process is steady and feasible, which has certain significance for normalizing the cutting process of Astragali Radix.

The Use of Microwave and Pulsed Electric Field as a Pretreatment Step in Ultrasonic Extraction of Polyphenols from Defatted Hemp Seed Cake (Cannabis sativa) Using Response Surface Methodology

The use of microwave and pulsed electric field (PEF) processing to optimize polyphenol extraction from defatted hemp seed cake in mixed solvent of methanol, acetone and water (MAW, 7:7:6 v/v/v) was investigated using the Box-Behnken response surface method. A variables combination for microwave processing of time, microwave power and liquid to solid (L:S) ratio and for PEF (ethanol concentration, time, frequency and voltage) were used in the investigation. Following microwave or PEF treatments, the polyphenols were extracted from the samples under ultrasound with fixed variables (200 W of ultrasonic power, water bath of 70 °C and 20 min of extraction time). The measured responses were total phenolics (TP), total flavonoids (TF), DPPH˙ scavenging activity and ferric reducing/antioxidant power (FRAP). The optimum variables combination for microwave processing (5 min treatment time, L:S ratio of 6, 700 W power and volume 30 mL) and PEF-assisted extraction (voltage (30 V), frequency (30 Hz), ethanol concentration (10 %) and time (10 s)) resulted in maximum yields in all measured responses. The results suggest that microwave processing and PEF can be integrated in processing defatted hemp seed cake to enhance polyphenol extraction and maximize the yield.

Statistical Optimization of Medium Components for Milk-Clotting Enzyme Production by Bacillus amyloliquefaciens D4 Using Wheat Bran-an Agro-Industry Waste

In this paper, two statistical methods were applied to optimize medium components to improve the production of the milk-clotting enzyme by Bacillus amyloliquefaciens D4. First, wheat bran juice, skim milk powder, and Na2HPO4 were shown to have significant effects on D4 enzyme production using the Plackett-Burman experimental design. Subsequently, an optimal medium was obtained using the Box-Behnken method, which consisted of 3.31 g/l of skim milk powder, 5.0 g/l of sucrose, 0.1 g/l of FeSO4·7H2O, 0.1 g/l of MgSO4·7H2O, 0.1 g/l of MnSO4·2H2O, 0.1 g/l of ZnSO4·7H2O, 1.52 g/l of Na2HPO4, and 172.45 g/l of wheat bran juice. With this optimal medium, the milk-clotting enzyme production was remarkably enhanced. The milk-clotting enzyme activity reached 3,326.7 SU/ml after incubation of 48 h, which was 1.76-fold higher than that of the basic medium, showing that the Plackett-Burman design and Box-Behnken response surface method are effective to optimize medium components, and B. amyloliquefaciens D4 possessed a high rennet-producing capacity in the optimal medium.

Statistical optimization of alkaline hydrogen peroxide pretreatment of sugarcane bagasse for enzymatic saccharification with Tween 80 using response surface methodology

Sugarcane bagasse is a byproduct constituting more than 25 % processed matter after cane juice extraction and is thus a low-cost renewable substrate for value-added products such as bioethanol and xylitol due to its high content of hemicellulose and cellulose. In this study, a Box–Behnken response surface method design was used to optimize alkaline hydrogen peroxide pretreatment of dilute acid-treated sugarcane bagasse. Hydrogen peroxide concentration (2–6 % w/v), pretreatment time (10–40 h) and liquid/solid ratio (8–20 v/w) were tested in order to maximize glucose production in the enzymatic hydrolysis process. The optimum conditions obtained were 4.7 % w/v hydrogen peroxide concentration, 26.7-h pretreatment time, and 17.1 v/w liquid/solid ratio, producing 31.1 g/L glucose (40.2 % glucose yield) at 72-h hydrolysis. After optimizing alkaline hydrogen peroxide pretreatment, a second Box–Behnken design was used to evaluate the effects of cellulase loading (3.4–5.6 filter paper unit (FPU)/g solid), β-glucosidase loading (15–27 beta-glucosidase unit (CBU)/g solid) and Tween 80 concentration (0.11–1.7 % w/v) on glucose production during enzymatic hydrolysis. By analyzing response surface plots and time course hydrolysis, 50.1 g/L glucose (64.8 % glucose yield) was obtained at 120-h hydrolysis using 4.1 FPU/g solids for cellulase, 18.2 CBU/g solids for β-glucosidase and 0.95 % w/v for Tween 80. This yield corresponds to a 29 % improvement in glucose concentration compared to no Tween 80 addition.

Statistical Optimization of Culture Conditions for Milk-Clotting Enzyme Production by Bacillus Amyloliquefaciens Using Wheat Bran-An Agro-Industry Waste

In order to improve the production of the milk-clotting enzyme under submerged fermentation, two statistical methods were applied to optimize the culture conditions of Bacillus amyloliquefaciens D4 using wheat bran as nutrient source. First, initial pH, agitation speed, and fermentation time were shown to have significant effects on D4 enzyme production using the Plackett-Burman experimental design. Subsequently, optimal conditions were obtained using the Box-Behnken method, which were as follows: initial pH 7.57, agitation speed 241rpm, fermentation time 53.3h. Under these conditions, the milk-clotting enzyme production was remarkably enhanced. The milk-clotting enzyme activity reached 1996.9SU/mL, which was 2.92-fold higher than that of the initial culture conditions, showing that the Plackett-Burman design and Box-Behnken response surface method are effective to optimize culture conditions. The research can provide a reference for full utilization of wheat bran and the production of milk-clotting enzyme by B. amyloliquefaciens D4 under submerged fermentation.

Preparation of Biocompatible Carboxymethyl Chitosan Nanoparticles for Delivery of Antibiotic Drug

Objective. To prepare biocompatible ciprofloxacin-loaded carboxymethyl chitosan nanoparticles (CCC NPs) and evaluate their cell specificity as well as antibacterial activity against Escherichia coli in vitro. Methods. CCC NPs were prepared by ionic cross-linking method and optimized by using Box-Behnken response surface method (BBRSM). Zeta potential, drug encapsulation, and release of the obtained nanoparticles in vitro were thoroughly investigated. Minimum inhibitory concentration (MIC) and killing profiles of free or ciprofloxacin-loaded nanoparticles against Escherichia coli were documented. The cytotoicity of blank nanoparticles and cellular uptake of CCC NPs were also investigated. Results. The obtained particles were monodisperse nanospheres with an average hydrated diameter of 151 ± 5.67 nm and surface of charge −22.9 ± 2.21 mV. The MICs of free ciprofloxacin and CCC NPs were 0.16 and 0.08 μg/mL, respectively. Blank nanoparticles showed no obvious cell inhibition within 24 h, and noticeable phagocytosis effect was observed in the presence of CCC NPs. Conclusion. This study shows that CCC NPs have stronger antibacterial activity against Escherichia coli than the free ciprofloxacin because they can easily be uptaken by cells. The obtained CCC NPs have promising prospect in drug delivery field.

Offshore Polymer Flooding Optimization Using Surrogate-Based Methodology

A surrogate-based optimization methodology was employed to optimize the offshore polymer flooding process based on a three-level Box-Behnken design and response surface method. The design variables selected in this study were polymer concentration, injection rate, and duration, and the performance measure was incremental net present value (NPV). Sensitivity analysis was performed and a quadratic model equation was fitted to the samples using the least-squares method and 0.98 of R2 adj meant a good fit. Optimization was performed using the constructed model and verified by numerical simulations. The possible range of maximum incremental NPV was studied using Monte Carlo simulations. The results showed that the methodology is effective and efficient and will be used as guidance for future petroleum engineering optimization.