A study of antifungal antibiotic production by Thermomonospora sp MTCC 3340 using full factorial design

The three independent variables, viz concentration of carbon source (glucose), concentration of nitrogen source (soybean meal) and temperature of incubation were found to be the most important for production of antifungal antibiotic by the isolate Thermomonospora sp MTCC 3340 from one‐factor‐at‐a‐time study. These variables were varied at three levels in a total number of 27 experiments designed using full factorial design. The results on analysis using the statistical software SPSS (version 6.0) indicated that the optimum combination of the three factors for the maximum yield of the antibiotic was concentration of carbon source (glucose) 2%, concentration of nitrogen source (soybean meal) 1% and temperature of incubation 30 °C. A close fit between experimental and predicted values of the antifungal yield was obtained using one of the modes derived from the statistical analysis, indicating that this model was applicable to this production. Copyright © 2003 Society of Chemical Industry     

Performance evaluation of an ANN–GA aided experimental modeling and optimization procedure for enhanced synthesis of marine biosurfactant in a stirred tank reactor

BACKGROUND: An improved resilient back‐propagation neural network modeling coupled with genetic algorithm aided optimization technique was employed for optimizing the process variables to maximize lipopeptide biosurfactant production by marine Bacillus circulans. RESULTS: An artificial neural network (ANN) was used to develop a non‐linear model based on a 2⁴ full factorial central composite design involving four independent parameters, agitation, aeration, temperature and pH with biosurfactant concentration as the process output. The polynomial model was optimized to maximize lipopeptide biosurfactants concentration using a genetic algorithm (GA). The ranges and levels of these critical process parameters were determined through single‐factor‐at‐a‐time experimental strategy. Improved ANN‐GA modeling and optimization were performed using MATLAB v.7.6 and the experimental design was obtained using Design Expert v.7.0. The ANN model was developed using the advanced neural network architecture called resilient back‐propagation algorithm. CONCLUSION: Process optimization for maximum production of marine microbial surfactant involving ANN‐GA aided experimental modeling and optimization was successfully carried out as the predicted optimal conditions were well validated by performing actual fermentation experiments. Approximately 52% enhancement in biosurfactant concentration was achieved using the above‐mentioned optimization strategy. © 2012 Society of Chemical Industry     

Peach-palm (Bactris gasipaes Kunth.) waste as substrate for xylanase production by Trichoderma stromaticum AM7

This work investigated the xylanase production by fungi isolates from tropical agroforestry systems using peach-palm industrial waste as a substrate. Trichoderma stromaticum AM7 was the best xylanase producer and there was a 160% increase in xylanase activity after optimizing by the Box–Behnken statistical design. The optimization process demonstrated that the maximum activity occurred at 0.95% nitrogen concentration after 6 days of cultivation at 32°C, which achieved a yield of 1440?U?g^?1 of dry initial substrate. Analysis by scanning electron microscopy showed degradation of the fibers after cultivation. The optimum pH and temperature for xylanase activity were 5.0 and 50°C, respectively. The extensive degradation of the peach-palm waste and xylanase production by T. stromaticum AM7 was due to the combination of a good physicochemical composition of the culture medium and the characteristics of the selected fungus.     

Optimization of <Emphasis Type="Italic">Brassica carinata</Emphasis> oil methanolysis for biodiesel production

Synthesis of FAME from Brassica carinata oil to produce biodiesel was accomplished using potassium hydroxide as the catalyst. A factorial design of experiments and a central composite design were used. The variables chosen were: type of Brassica carinata oil, initial catalyst concentration, and temperature; and the responses were FAME purity and yield. The type of B. carinata oil included high-erucic B. carinata (HEBC) and lowerucic B. carinata (LEBC) varieties. The results show that the type of B. carinata oil does not affect the purity and yield of FAME. However, HEBC oil is more suitable for biodiesel production because its iodine value is lower and within the European Union specifications. The initial catalyst concentration is the most important factor, having a positive influence on FAME purity but a negative effect on FAME yield. The temperature has a significant positive effect on FAME purity and a significant negative influence on FAME yield. Second-order models were obtained to predict FAME purity and yield as a function of catalyst concentration and temperature for HEBC oil methanolysis. The best conditions for this process are 25°C, and 1.2–1.5 wt% for the catalyst concentration.     

Application of response surface methodology to optimize the operation process for regeneration of acid and base using bipolar membrane electrodialysis

BACKGROUND: Bipolar membrane electrodialysis (BMED) has been widely used for desalination, concentration, separation, and purification in many fields. The purpose of this study is to optimize the operation conditions using response surface methodology (RSM) for the regeneration of sulfuric acid and ammonia from ammonium sulfate solution by BMED coupled with ammonia in situ stripping. RESULTS: A three‐factor central composite design of RSM was used to analyze the effect of operation conditions (current density, flow rate, initial acid concentration) on average current efficiency (ACE) and establish the optimal operation conditions. The ACE was 76.7 ± 2.2% under optimal operation conditions (current density 23.8 mA cm^?2, flow rate 27.3 L h^?1, initial acid concentration 0.09 mol L^?1). CONCLUSION: A suitable regression model for predicting ACE within the ranges of variables used was developed based on experimental results. The operation conditions were optimized by RSM and the ACE obtained under the optimal operation conditions was in good agreement with the value predicted by the regression model (78%), which proved the validity of the model. Copyright © 2007 Society of Chemical Industry     

Efficient acetoin production by optimization of medium components and oxygen supply control using a newly isolated Paenibacillus polymyxa CS107

BACKGROUND: Acetoin is a natural flavor commonly used in wine, buffer, honey, garnet berry and strawberry as a food additive. It also has been widely applied in cosmetics, pharmacy and chemical synthesis. Culture medium optimization and process control were carried out for efficient production of acetoin by a newly isoliated P. polymyxa CS107. RESULTS: An acetoin high producing strain, designated as CS107, was newly isolated and identified as P. polymyxa based on its physiological and biochemical characteristics as well as the 16S rDNA sequence. The medium composition was optimized in shake flask fermentations by a sequential statistical experimental design. Under the optimized conditions, acetoin concentration of 30.98 g L^?1 was achieved with 71.83% of theoretical glucose conversion efficiency. Fed‐batch fermentation based on a suitable agitation speed was carried out in a 5 L jar, the maximum acetoin concentration of 55.3 g L^?1 was obtained with the productivity of 1.32 g L^?1 h^?1 and the yield of 75.62%. CONCLUSION: A new strain for efficient production of acetoin, designated as P. polymyxa CS107, was obtained. The optimization of fermentation variables and fed‐batch culture resulted in a maximum acetoin concentration of 55.3 g L^?1 in 5 L jar. Copyright © 2012 Society of Chemical Industry     

Optimization of the Iron Electro-Coagulation Process of Cr,Ni, Cu,and Zn Galvanization By-Products by Using Response Surface Methodology

An electrocoagulation laboratory scale system was studied for the removal of inorganic pollutants from a mixture of galvanic process-based by-products. Response surface methodology based on a five-level, four-variable central composite rotatable design was employed for optimization with respect to four important variables—reaction time, agitation velocity, current density, and pH. The electrocoagulation process response was evaluated on the basis of chemical oxygen demand (COD), turbidity, total suspended solid, and element concentration values. Interaction effects between reactor operating variables and response variables were evaluated by using 3-D response surface analysis Second-order models were validated by ANOVA. Predicted yields were in a good agreement with the experimental ones. The reactor optimal performance was achieved at 35 min reaction time, 170 rpm agitation velocity, 97.7 Am^?2 current density, and 6.5 initial pH. Under these conditions 100% color and turbidity, 90% COD and total suspended solids, 100% chromium and nickel, and almost 99% zinc and copper were removed. A pseudo-first-order rate model was applied to describe the metal removal kinetics. The EC treatment of heavy metal solutions proved to be more cost-effective than the conventional one, indicating clearly that the method of electro-coagulation is a very promising alternative for industrial applications.     

Effect of different fermentation parameters on bioethanol production from corn meal hydrolyzates by free and immobilized cells of Saccharomyces cerevisiae var. ellipsoideus

BACKGROUND: Bioethanol produced from renewable biomass, such as corn meal, is a biofuel that is both renewable and environmentally friendly. Significant scientific and technological investments will be needed to achieve substitution of conventional fossil fuels with alternative fuels. The ethanol fermentation of enzymatically obtained corn meal hydrolyzates by free and immobilized cells of Saccharomyces cerevisiae var. ellipsoideus yeast in a batch system was studied. The initial glucose and inoculum concentration and the time required for the efficient ethanol production were optimized taking into account parameters such as ethanol concentration, ethanol yield, percentage of the theoretical yield of ethanol and volumetric productivity in both immobilized and free cell systems. RESULTS: The yeast cells were immobilized in Ca–alginate by an electrostatic droplet generation method. An optimal initial inoculum concentration of 2% (v/v) and optimal fermentation time of 38 h for both immobilized and free yeasts were determined. An optimal initial glucose concentration of 150 g L^?1 for free system was achieved. At the initial glucose concentration of 176 g L no substrate or product inhibition were achieved with immobilized yeast. CONCLUSION: By immobilization of the yeast into Ca–alginate using the method of electrostatic droplet generation a superior system was realized, which exhibited lower substrate inhibition and higher tolerance to ethanol. The cells of S. cerevisiae var. ellipsoideus yeast entrapped in Ca–alginate showed good physical and chemical stability, and no substrate and product diffusion restrictions were noticed. Copyright © 2008 Society of Chemical Industry     

Lipase‐catalyzed production of medium‐chain triacylglycerols from palm kernel oil distillate: Optimization using response surface methodology

Optimization of lipase‐catalyzed esterification for the production of medium‐chain triacylglycerols (MCT) from palm kernel oil distillate and glycerol was carried out in order to determine the factors that have significant effects on the reaction system and MCT yield. Novozyme 435 from Candida antarctica lipase was found to have the highest activity at 52.87 ± 0.03 U/g. This lipase also produced the highest MCT yield, which is 56.67%. The effect of different variables on MCT synthesis was studied with a two‐level five‐factor fractional factorial design. The various variables include (1) reaction temperature, (2) enzyme load, (3) molecular sieves concentration, (4) reaction time and (5) molar substrate ratio. Reaction temperature, reaction time and molar substrate ratio strongly affect MCT synthesis (p <0.05). However, enzyme load and molecular sieve concentration did not have a significant (p >0.05) influence on MCT yield. Therefore, the significant variables such as reaction temperature, reaction time and molar substrate ratio were further optimized through central composite rotatable design (CCRD). Comparisons between predicted and experimental values from the CCRD optimization procedures revealed good correlation, implying that the quadric response model satisfactorily expressed the percentage yield of MCT in the lipase‐catalyzed esterification. The optimum MCT yield is 73.3% by using 2 wt‐% enzyme dosage, a molecular sieves concentration of 1 wt‐%, a reaction temperature of 90 °C, a reaction time of 10 h and a molar substrate ratio of 4 : 1 (medium‐chain fatty acid/glycerol). Experiments to confirm the predicted results using the optimal parameters were conducted and an MCT yield of 70.21 ± 0.18% (n = 3) was obtained.     

Optimization and Characterization of Biosurfactant Rhamnolipid Production by Pseudomonas aeruginosa Isolated from an Artificially Contaminated Soil

Biosurfactants are surfactants biologically produced by microorganisms, presenting several advantages when compared to synthetic surfactants. Pseudomonas aeruginosa is known for producing rhamnolipids, considered one of the most interesting types of biosurfactants due to their high yields, when compared to other types. In this work, the production of rhamnolipid from P. aeruginosa was optimized. At first, the Plackett–Burman design was used to select most significant variables affecting the biosurfactant production yield among nine variables—carbon–nitrogen ratio, carbon concentration, nitrogen source, pH, cultivation time, potassium and magnesium concentrations, agitation, and temperature. Then, using main variables, a central point experimental design aiming to optimize rhamnolipid production was performed. The maximum biosurfactant concentration obtained was 0.877 mg L⁻¹. The rhamnolipid also displayed a great emulsification rate, reaching approximately 67%, and the ability to reduce water surface tension from 72.02 to 35.26 mN m⁻¹ at a critical micelle concentration (CMC) of 127 mg L⁻¹, in addition to presenting a good stability when exposed to wide pH and salinity ranges. The results suggest that rhamnolipids are promising substitutes for synthetic surfactants, especially due to lower impacts on the environment.     

Optimization of media constituents through response surface methodology for improved production of alkaline proteases by Serratia rubidaea

BACKGROUND: Response surface methodology is used to build a predictive model of the combined effects of independent variables (pH, salt concentration starch and casein). The model was validated in a laboratory‐scale bioreactor for extracellular protease production from a newly isolated Serratia rubidaea. RESULTS: Optimum medium conditions obtained from the optimization experiments after 48 h incubation were starch, 8 g L^?1; casein, 4 g L^?1; salt concentration 6.25 g L^?1; and initial pH, 8. A coefficient of determination (R²) value of 0.9305 shows the fitness of the second‐order model for the present studies. Results of model coefficients estimated by multiple linear regressions indicate that linear effects of casein concentration (P < 0.001308) and initial pH (P < 7.91 E‐07) are more significant than similarly interactive effects of starch and casein (P < 0.019153), casein and salt concentration (P < 0.016294), casein and pH (P < 0.039904) and salt concentration and pH (p < 0.017845). The P‐values of quadratic effects of casein, x2 × x2 (P < 0.000171); SC, x3 × x3 (P < 0.009134); initial pH, x4 × x4 (P < 0.000114) are more significant for maximal production. After optimization, protease production was enhanced experimentally by almost 65% in a shake flask and by almost 115% in a bioreactor. CONCLUSION: The alkaline proteases secreted by S. rubidaea were significant from an industrial perspective because of their stability against surfactants, oxidants and solvents. The statistical design is useful in economic protease production in a cost‐effective medium for potential use on an industrial scale. Copyright © 2007 Society of Chemical Industry     

Optimization of polypropylene/clay nanocomposite processing using Box‐Behnken statistical design

A wide range of process parameters regulate the final morphology achieved in layered silicate based polymer nanocomposites. This study deals with the optimization of process variables to improve the matrix formulation. A three‐factor, three‐level Box‐Behnken design with compatibilizer concentration (X₁), clay concentration (X₂), and screw speed (X₃) as the independent variables were selected for the study. The dependent variable was mechanical property of the final nanocomposites. Maleic anhydride grafted polypropylene (PP‐g‐MA) compatibilizer and organoclay (Cloisite 15A) was melt blended with polypropylene separately in a corotating twin screw extruder. The clay was modified with fluorescent dye Nile Blue A Perchlorate (NB) and the adsorbed dye content in the clay gallery was estimated by using UV‐spectrophotometric method. The Minitab‐15 software was used for analysis of the results obtained. Optimum compositions for better dispersion were achieved from contour plots and response surface methodology. It was supported by a unique fluorescence spectrophotometry along with transmission electron microscopy and X‐ray diffraction technique. An intensity ratio close to unity showed a better exfoliated morphology. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Optimization of pullulan production from synthetic medium by Aureobasidium pullulans in a stirred tank reactor by response surface methodology

The production of pullulan from synthetic medium by Aureobasidium pullulans P56 in a stirred tank fermenter was investigated. The kinetics of polysaccharide, pullulan and biomass production was determined. Response surface methodology was used to investigate the effects of three factors (initial sugar concentration, aeration rate and agitation speed) on the concentration of pullulan in batch cultures of A pullulans. In the experiments, the range of values used for the three variables described were; 30–70 g dm^?3 initial sugar concentration, 200–600 rpm agitation speed and 1.0–3.0 vvm aeration rate. No previous work has used statistical analysis in determining the interactions among these variables in pullulan production. Results of the statistical analysis showed that the fit of the model was good in all cases. Aeration rate, agitation speed and sugar concentration had a strong linear effect on pullulan concentration. Moreover, pullulan concentration was significantly influenced by the negative quadratic effects of the given variables and by their positive or negative interactions with the exception that the interaction between agitation speed and aeration rate was insignificant (P > 0.05). Maximum pullulan concentration of 17.2 g dm^?3 was obtained at the optimum levels of process variables (initial sugar concentration 51.4 g dm^?3, aeration rate 2.36 vvm, agitation speed 345.3 rpm). These values were obtained by fitting of the experimental data to the model equation. Scanning electron microscope (SEM) photographs of polysaccharide particles containing different concentrations of pullulan were also taken to observe the morphological differences of the samples. Copyright © 2005 Society of Chemical Industry     

Optimization of the production of chitosan from beet molasses by response surface methodology

Chitosan was produced by Rhizopus oryzae 00.4367 in shake flask culture and a stirred tank fermenter. Synthetic medium, treated and untreated beet molasses were used as cultivation media in shake flask cultures. In the stirred tank fermenter, the cultivation media were synthetic medium and untreated beet molasses. Shake flask culture containing untreated molasses with a sugar concentration of 40 g dm^?3 produced the maximum chitosan yield (961 mg dm^?3). Chitosan concentration reached its maximum value at the late exponential growth phase of R oryzae. In all experiments almost 8–10% of biomass and 32–38% of alkali‐insoluble material was extracted as chitosan. A central composite design was employed to determine the optimum values of process variables (aeration rate, agitation speed and initial sugar concentration) leading to maximum chitosan concentration in the stirred tank fermenter. In all cases, the fit of the model was found to be good. Aeration rate, agitation speed and initial sugar concentration had a strong linear effect on chitosan concentration. Moreover, the concentration of chitosan was significantly influenced by the negative quadratic effects of the given variables and by their positive or negative interactions. A maximum chitosan concentration of 1109.32 mg dm^?3 was obtained in untreated molasses medium containing an initial sugar concentration of 45.37 g dm^?3 with an aeration rate and agitation speed of 2.10 vvm and 338.93 rpm, respectively. Copyright © 2004 Society of Chemical Industry     

Optimization of cordycepin extraction from cultured Cordyceps militaris by HPLC‐DAD coupled with uniform design

BACKGROUND: Uniform design was used to optimize the ultrasonic‐assisted extraction of cordycepin from cultured Cordyceps militaris. The peak area of cordycepin identified using high performance liquid chromatography (HPLC) at a detection wavelength of 260 nm was considered the detection index. Three factors, ethanol concentration, extraction time and volume ratio of solvent to sample were studied. Optimal quadric polynomial step by step regression was applied to process the experimental results. RESULTS: Results show that the main factors affecting cordycepin extraction yield were the volume ratio of solvent to sample, extraction time and ethanol concentration, in that order. Cordycepin extraction yield reached a peak with ethanol concentration 20.21%, extraction time 101.88 min, and volume ratio of solvent to sample 33.13 mL g^?1. An extraction model was developed based on the findings. CONCLUSION: A direct, reliable and accurate assay has been developed for the quantification of cordycepin in cultured Cordyceps militaris by a HPLC‐DAD method. The validation procedure confirmed that this method is appropriate for the quality control of cordycepin. Results show that the uniform experimental design approach is useful for finding polynomial functions describing the relationships between variables and responses and to find the best experimental conditions for the extraction of cordycepin in the experimental domain considered. Copyright © 2007 Society of Chemical Industry     

Effects of process parameters on heterologous protein production in Aspergillus niger fermentation

Filamentous fungi such as Aspergillus niger are attractive hosts for recombinant DNA technology because of their ability to secrete bioactive proteins with post‐translational processing such as glycosylation. Foreign genes can be incorporated into the chromosomes of the filamentous fungi, providing superior long‐term genetic stability. However, heterologous protein production is often severely hampered by fungal proteases. In this work, a recombinant Aspergillus niger strain AB4.1[pgpdAGLAGFP]#11 which carries a glucoamylase (GLA)‐green fluorescent protein (GFP) fusion gene was selected as a model system to study the effects of bioprocess parameters—agitation intensity, initial glucose concentration, initial yeast extract concentration, and dissolved oxygen tension (DO)—on extracellular protease inhibition and heterologous protein production. Based on previous experimental experience and results, a 2^4–1 fractional factorial design was applied to the experiments. Each parameter was tested at two levels. It was found that agitation affected the GFP production most significantly. Higher agitation rate resulted in higher GFP production. Protease activity was most influenced by initial glucose concentration and DO. Fungal morphology was also affected by these parameters. The effects of these parameters on pellet size and pellet porosity are discussed. Copyright © 2003 Society of Chemical Industry     

The effect of fermentation parameters on the production of Mucor miehei acid protease in a chemically defined medium

Batch shake flask experiments were carried out with a fungal strain of Mucor miehei ATCC 3420 to study the effects of five fermentation parameters; initial D ‐glucose concentration, temperature, initial pH, agitation rate and inoculum ratio, on the production of rennin in a chemically defined medium. A statistical design was used to assign the experimental levels of five fermentation parameters for the determination of optimum conditions. The highest concentration of milk‐clotting activity (MCA) obtained was 2286 SU cm^?3 (without concentration of the broth) at 29.6 g dm^?3 initial D ‐glucose concentration, 6.8 initial pH, 37.6 °C temperature, 81 stroke per min agitation rate and 5.2% (v/v) inoculum ratio. Although enzyme secretion was a function of all the operational parameters investigated, the pH range (4.6–5.2) reached at the time of enzyme production had a profound effect on milk‐clotting activity levels. In the fermentation sample at maximum milk‐clotting activity the R factor, the ratio of milk‐clotting activity to proteolytic activity, was determined as 1 SU PU^?1, denoting similar characteristics to a commercial animal rennet. © 2001 Society of Chemical Industry     

Effect of the polymerization conditions on the swelling of a copolymer of AA/AMPS/BA via experimental design

To study the effect of the polymerization conditions on swelling, a copolymer was synthesized from the monomers acrylamide (AA), 2‐acrylamido‐2‐methyl‐propanosulfonic acid (AMPS) and N,N‐methylenobisacrylamide (BA) as crosslinker by an inverse emulsion technique. The conditions were: concentration of organic solvent, s (an isoparaffinic hydrocarbon, commercially Isopar M), concentration of emulsifier, e (sorbitan trioleate, commercially Tween 85), and reaction temperature, T. These three variables (factors) were explored to achieve highest water absorbency, a 2³ factorial experimental design having been applied to find the main and two‐factor interaction effects of those variables on the swelling capacity. A predictive model including the factors for the swelling is proposed, allowing for the estimation of absorbency capacity in this type of copolymers. The results show that the optimum values of the variables given by the experimental design were s = 8.1, e = 1.0, and T = 49°C, with predicted swelling capacity of 1041 and experimental of 1014. The variables are relevant, with a preponderance of s, and the effect of the square of temperature is also significant. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Development and optimization of cultured goat cream butter

A central composite design 2²+star based on response surface methodology was used for development and optimization of a cultured goat cream butter formulation (cultured). The goat milk cream was inoculated with freeze-dried mesophilic aromatic lactic cultures and showed an increase in acidity and a aromatic lactic cultures and showed an increase in acidity and a decrease in lactose content when the concentration of lactic cultures was increased. An optimized temperature of 28°C was chosen for fast acid production in the goat milk cream. The lactic culture concentration significantly affected flavor, sensory texture, and overall quality, but the fermentation process were an inoculum dosage of 8.8 U/100 L and a fermentation time of 7 h at 28°C. This cultured formulation achieved optimal sensory quality in the attributes appearance, flavor, texture, and overall quality. At refrigerator temperature (4°C) the cultured formulation behaved as a solid and lacked spreadability, whereas it had ideal spreadability at 15°C when the solid fat content (SFC) was around 18.0%. At room temperature (18–25°C) the SFC was between 11 and 8%, respectively.     

Optimization of lipase production by Penicillium simplicissimum in soybean meal

BACKGROUND: Lipase production by Penicillium simplicissimum using soybean meal as substrate has been investigated. A factorial design technique was used to evaluate the effects of incubation temperature, initial moisture of the meal and substrate supplementation with low cost supplements, on lipase production. Soybean oil and wastewater from a slaughterhouse, which is rich on oil and fat, corn steep liquor and yeast hydrolysate, were tested as supplementary carbon and nitrogen sources. RESULTS Cultivation conditions were optimized for the production of lipase by factorial design and response surface methodology. Results show that the microorganism produces very low protease activity (0.21 U gds^?1 dry substrate), which helps to maximize lipase production. Soybean meal without supplements appears to be the best medium of those tested for lipase production by P. simplicissimum. CONCLUSION: This work showed that temperature and moisture are the factors that most strongly influence lipase production by P. simplicissimum using soybean meal as substrate. The growth conditions that optimize lipase production are 27.5 °C using substrate with 550 g kg^?1 of initial moisture. In optimum conditions lipase activity of 30 U gds^?1 dry substrate was obtained. Copyright © 2007 Society of Chemical Industry