Statistics-based Experimental Design Research Articles

Optimization of Bacillus amyloliquefaciens BLB369 Culture Medium by Response Surface Methodology for Low Cost Production of Antifungal Activity.

Bacillus amyloliquefaciens BLB369 is an important plant growth-promoting bacterium, which produces antifungal compounds. A statistics-based experimental design was used to optimize a liquid culture medium using inexpensive substrates for increasing its antifungal activity. A Plackett–Burman design was first applied to elucidate medium components having significant effects on antifungal production. Then the steepest ascent method was employed to approach the experimental design space, followed by an application of central composite design. Three factors were retained (candy waste, peptone, and sodium chloride), and polynomial and original trigonometric models fitted the antifungal activity. The trigonometric model ensured a better fit. The contour and surface plots showed concentric increasing levels pointing out an optimized activity. Hence, the polynomial and trigonometric models showed a maximal antifungal activity of 251.9 (AU/mL) and 255.5 (AU/mL) for (19.17, 19.88, 3.75) (g/L) and (19.61, 20, 3.7) (g/L) of candy waste, peptone, and NaCl, respectively. This study provides a potential strategy for improving the fermentation of B. amyloliquefaciens BLB369 in low-cost media for large-scale industrial production.

Optimized production of extracellular alkaline protease from Aspergillus tamarii with natural by-products in a batch stirred tank bioreactor

Proteolytic enzymes are one of the significant commercially manufactured enzymes. The manufacture of extracellular alkaline protease by Aspergillus tamarii MTCC5152 was explored using several agricultural by-products as substrates viz., cottonseed meal, wheat bran, skimmed milk and soya flour in submerged fermentation, were found to be efficient for enzyme production and commercially significant. Response surface methodology (RSM) is a statistics-based experimental design, sourced to explore the impact of physical parameters on the manufacture of protease from A. tamarii in a batch stirred tank bioreactor (STBR). The four substantial variables (pH, temperature, inoculum size, and agitation) were carefully chosen for optimization analyses and the statistical pattern was created using a central composite design and the quadratic model has been developed. The optimum conditions for protease production (1.51 U mL−1) where: pH 6.4, temperature 27 °C, inoculum size 2.6%, and agitation 327 rpm. The analysis revealed that the anticipated values were in accord with trial data with a correlation coefficient of 0.969.

Arsenic removal by the micellar-enhanced ultrafiltration using response surface methodology

Abstract The present research investigates the removal of arsenic (As) from aqueous solutions using micellar-enhanced ultrafiltration (MEUF) by utilizing two different surfactants: benzethonium chloride and dodecyl pyridinium chloride (BCl and DPCl). The impact of the operating variables and maximum removal efficiency were found under different conditions for BCl and DPCl surfactants. The maximum As rejection efficiency for MEUF with BCl and DPCl surfactants is 92.8% and 84.1%, respectively. In addition to this, a statistics-based experimental design with response surface methodology was used for the purpose of examining the impact of operating conditions, including initial pH, initial As concentration (ppb), and surfactant concentration (BCl, mM) in As-removal from aqueous solutions. In the analysis of the experimental data, a second-order polynomial model that was validated by statistical analysis for the BCl surfactant was used. On the basis of the response model created, the removal of As ions was acquired at optimum operating parameters, including the initial As concentration of 150 ppb, surfactant concentration of 5 mM and pH 10 for the BCl surfactant with 92.8% As-removal efficiency.

Medium Optimization for Synaptobrevin Production Using Statistical Methods

Background: Botulinum toxin, the most potent biological toxin, has become a powerful therapeutic tool for a growing number of clinical applications. Molecular studies have identified a family of synaptic vesicle-associated membrane proteins (VAMPs, also known as synaptobrevins) which have been implicated in synaptic vesicle docking and fusion with plasma membrane proteins. Materials and Methods: Using the synaptobrevin as a substrate for in vitro assay is the method to detect BoNT activity. We have been working on optimizations of bacterial expression conditions and media for high-level production of synaptobrevin peptide. Statistics-based experimental design was used to investigate the effect of medium components (E. coli strain, peptone, IPTG, yeast extract, ampicillin, and temperature) on synaptobrevin production by E. coli. Results: A 24 fractional factorial design with center points revealed that IPTG and temperature were the most significant factors, whereas the other factors were not important within the levels tested. This purpose was followed by a central composite design to develop a response surface for medium optimization. The optimum medium composition for synaptobrevin production was found to be: IPTG 29 mM, peptone 10 g/L, yeast extract 5 g/L, temperature 23°C and ampicillin 100 mg/L. This medium was projected to produce, theoretically, 115 mg/L synaptobrevin. Conclusion: The optimum medium composition synaptobrevin production was found to be: BL21 (E.coli strain), LB medium (peptone 10 g/L, Yeast 5 g/L), Ampicillin (100 mg/L), IPTG (0.29 mg/L) and temperature (23°C). Keywords: synaptobrevin; E. coli; experimental designs; central composite design; medium optimization

Experimental Design Considerations for Calibration of Semispan Force Measurement Systems

Experimental design considerations for the development of calibration load schedules are discussed for the characterization of traditional five-component semispan balances used in aerodynamic ground testing applications. Detail is given on traditional semispan balance design, use of these types of balances, and a survey of some of the calibration systems currently used to calibrate these measurement systems. Techniques are presented to develop experimental calibration designs used to calibrate these instruments, with consideration given to accounting for physical limitations existing within these calibration systems. The techniques provided rely on traditional statistical engineering approaches, leveraging off of statistics-based experimental design techniques and analysis metrics used to assess the characteristics of the designs. Methods used for optimal design techniques are presented, with a case study given that details the comparison of these statistics-based metrics for traditional and optimized calibration load schedule designs.

Effects of electrophoretic deposition parameters on the photocatalytic activity of TiO2 films: Optimization by response surface methodology

In this work, the electrophoretic deposition method was utilized to immobilize TiO2 particles on stainless steel substrates. In addition, for the first time, statistics-based experimental design using response surface methodology was employed to investigate the effect of four key coating parameters (i.e. applied voltage, calcination temperature, photocatalyst weight percentage, and deposition time) on the photocatalytic degradation. Analysis of variance revealed that the proposed model was adequate. X-ray diffraction and scanning electron microscope were used to evaluate the effects of the parameters on degradation efficiency. The optimum applied voltage, calcination temperature, catalyst concentration and deposition time were found to be 25V, 300°C, 1.0wt%, and 300s, respectively. Under these conditions, the degradation efficiency reached 85.88%.

Optimization of Magnetosome Production and Growth by the Magnetotactic Vibrio Magnetovibrio blakemorei Strain MV-1 through a Statistics-Based Experimental Design

The growth and magnetosome production of the marine magnetotactic vibrio Magnetovibrio blakemorei strain MV-1 were optimized through a statistics-based experimental factorial design. In the optimized growth medium, maximum magnetite yields of 64.3 mg/liter in batch cultures and 26 mg/liter in a bioreactor were obtained.

Enzymatic decolorization of Orange II: Optimization by response surface methodology and pathway

Statistics‐based experimental design with response surface methodology (RSM) was applied to optimize the operating conditions in decolorization of Orange II by horseradish peroxidase (HRP) in the presence of H2O2. Four critical factors (i.e., HRP concentration, H2O2 concentration, pH, and reaction time) were used for the optimization of enzymatic decolorization using RSM. The optimized conditions of the enzymatic degradation of Orange II were as follows: HRP concentration, 0.80 U/mL; H2O2 concentration, 0.70 mM; pH, 9.0; reaction time, 40 min. The maximal decolorization efficiency of 95.83% was achieved at the optimized conditions. The analysis of UV–vis spectra and electrospray ionization–time of flight–mass spectrometry indicated that both decomposition and coupling reaction occurred in the enzymatic decolorization. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 294‐301, 2013

Application of response surface methodology in the optimisation of a growth medium for enhanced natural preservative bacteriocin production by a probiotic bacterium

In this study, a statistics-based experimental design was utilised for the optimisation of a growth medium which possibly enhanced bacteriocin production by Streptococcus phocae PI80. Carbon, nitrogen sources and a bio-surfactant were first screened using a one variable at a time technique and scored for increasing yield production. The selected variables were further statistically optimised using response surface methodology with a central composite design. The high- and low-level limits of the selected variables were determined, and a set of 34 experimental runs were performed. The concentration of each medium ingredient influenced the bacteriocin activity to about 22,500 AU mL–1. The carbon and nitrogen sources were identified as significant factors in restraining the bacteriocin activity produced by S. phocae PI80. The statistics-based experimental design was found to be very efficient in optimising the media components in a number of experimental runs, with a three-fold increase in bacteriocin activity compared to the un-optimised medium. The optimum medium composition was found to be sodium succinate (10.0 g L−1), yeast extract (4.0 g L−1), glucose (9.0 g L−1), NaCl (10.0 g L−1), Tween 80 (6.0 g L−1) and K2HPO4 (1.0 g L−1). This optimised medium is two-fold more cost effective than the commercial Lactobacillus MRS medium.

Response surface methodological approach for the assessment of the photocatalytic degradation of NOM

In this paper, statistics-based experimental design with response surface methodology (RSM) was employed to investigate the effects of operational conditions on the photocatalytic oxidation of humic acid as a model compound of natural organic matter. Considering the vast number of the obtained experimental data, in this study, a correlative approach was employed for the assessment of the photocatalytic degradation efficiency of humic acids (HA) using an empirical method for the optimization of the key parameters such as photocatalyst dose, pH and humic acid concentration. The results of this study revealed that the regression analysis showed a close fit ( R 2 > 0.83) between the experimental results and the model predictions. Maximum DOC removal was achieved as 89.3% under the experimental conditions of 30 mg/L humic acid, 2.0 mg/mLTiO 2 and pH = 7. Under acidic conditions (pH = 5), and in the presence of 1.0 mg/mLTiO 2 almost complete removal of UV absorbing centers were attained for 30 mg/L humic acid. Exhaustive decolorization was attained under alkaline conditions (pH = 8), for the photocatalyst loading of 1.5 mg/mLTiO 2 for 18.5 mg/L humic acid. The role of the irradiation period on the removal efficiency of the specified parameters were expressed by the relation between the predicted values attained for irradiation periods (40 min and 60 min) that were presented by the correlation coefficients as R 2 = 0.847, 0.691 and 0.700 for DOC, UV 254 and Color 436 respectively. Moreover, model verification was also reported for a selected humic acid substrate and a specified photocatalyst specimen.

Optimization of photocatalytic production of hydrogen from hydrogen sulfide in alkaline solution using response surface methodology

In this paper, statistics-based experimental design with response surface methodology (RSM) was employed to investigate the effects of operation conditions on photocatalytic production of Hydrogen from Hydrogen sulfide in alkaline solution. Initially, the Box–Behnken design was employed including the three key variables (concentration of sulfide ion, pH and amount of catalyst). Thereafter, the mutual interaction and effects between parameters and optimum conditions were obtained in greater detail by means of Statease Design expert Software. The results of this investigation reveal that (i) Regression analysis with R2 value of 99.56 shows a close fit between the experimental results and the model predictions; (2) Contour plot can provide a good manner for visualizing the parameter interactions; (3) Optimum concentration of sulfide ion; pH and catalyst amount is found to be 3.9g/L, 11.3, 500mg/L respectively, and the highest conversion efficiency of 24.93% can be achieved.

Optimization by factorial design of copper (II) and toxicity removal using a photocatalytic process with TiO 2 as semiconductor

The photochemical process of Cu (II) reduction by heterogeneous photocatalysis using titanium dioxide (TiO 2) Degussa P-25 and a 254 nm UV-C lamp was studied. The aim of this work was to determine the efficiency of the photocatalytic process to remove 100 ppm of copper (II) ion concentration from a water solution. A statistics-based experimental design with response surface methodology (RSM) was employed to investigate the effect of operating conditions on photocatalytic reduction. The experimental results were evaluated using multivariate analysis with the program MODDE 7.0. The parameters studied were catalyst mass, pH, and reaction time. After optimizing the variables, degradation kinetics were performed to corroborate the model. The regression analysis with R 2 value of 0.98 shows a close fit between the experimental results and the model predictions. The value obtained for the reaction rate constant was 0.0246 min −1. Three-dimensional response surface plots were used to visualize parameter interactions. The optimum pH (4.3) and titanium dioxide mass (0.5 g) achieved the highest efficiency, reaching 80% of copper (II) ion reduction. Two different bioassays, using Daphnia magna and Pseudomonas aeruginosa, were performed to determine acute toxicity reduction after the treatment. The results obtained show that the bio-toxicity reduction reached 80%.

Optimising photoelectrocatalytic oxidation of fulvic acid using response surface methodology

In this paper, statistics-based experimental design with response surface methodology (RSM) was employed to investigate the effect of operation conditions on photoelectrocatalytic oxidation of fulvic acid (FA) using a Ti/TiO 2 electrode in a photoreactor. Initially, the Box–Behnken design was employed including the three key variables (initial pH, potassium peroxodisulphate (K 2S 2O 8) and bias potential). Thereafter, the mutual interaction and effects between these parameters and optimum conditions were obtained in greater detail by means of SAS and Matlab software. The results of this investigation reveal that: (1) the regression analysis with R 2 value of 0.9754 shows a close fit between the experimental results and the model predictions; (2) three-dimension response surface plot can provide a good manner for visualizing the parameter interactions; (3) the optimum pH, K 2S 2O 8 and bias potential is found to be 3.8, 88.40 mg/L, 0.88 V, respectively, and the highest FA removal efficiency of 57.06% can be achieved.

Enhanced production of an extracellular protease from Beauveria bassiana by optimization of cultivation processes

Statistics-based experimental design, response surface methodology was employed to investigate the effect of medium components on the production of extracellular protease from Beauveria bassiana A1. The optimum medium composition for protease production was found to be (in %, w/v): 0.72 shrimp shell powder, 0.60 soy powder, 0.19 sucrose and 0.68 yeast extract. This medium was projected to produce, theoretically, 281.14 U/ml. By using this medium, an experimental maximum protease activity of 280.72 U/ml in 7 days cultivation verified the applied methodology. Further studies on bioreactor production of protease were investigated in a 5 l stirred-tank and 30 l airlift bioreactors. In 5 l stirred-tank bioreactor, a maximum protease activity of 238.77 U/ml was attained in 6 days of cultivation when aeration rate and agitation speed were controlled at 0.6 vvm and 150 rpm, respectively. On the other hand, in 30 l airlift bioreactor the maximum protease activity of 283.84 U/ml was found with the controlled aeration rate of 0.9 vvm operated in a bubble column mode. This activity in the 30 l airlift bioreactor was close to that obtained from the shaker-flask cultivation study (280.72 U/ml). However, the duration of cultivation period using 30 l airlift bioreactor was shorter than the corresponding duration obtained from the shaker-flask cultivation by 4 days.

Medium optimization for hen egg white lysozyme production by recombinant Aspergillus niger using statistical methods

Statistics-based experimental design was used to investigate the effect of medium components (starch, peptone, ammonium sulfate, yeast extract, and CaCl2.2H2O) on hen's egg white lysozyme production by Aspergillus niger HEWL WT-13-16. A 2(5-1) fractional factorial design augmented with center points revealed that peptone, starch, and ammonium sulfate were the most significant factors, whereas the other factors were not important within the levels tested. The method of steepest ascent was used to approach the proximity of optimum. This task was followed by a central composite design to develop a response surface for medium optimization. The optimum medium composition for lysozyme production was found to be: starch 34 g L-1, peptone 34 g L-1, ammonium sulfate 11.9 g L-1, yeast extract 0.5 g L-1, and CaCl2.2H2O 0.5 g L-1. This medium was projected to produce, theoretically, 212 mg L-1 lysozyme. Using this medium, an experimental maximum lysozyme concentration of 209+/-18 mg L-1 verified the applied methodology.