Application of response surface methodology to cell immobilization for the production of palatinose

Animal and Clinical Studies Evaluating Blood Glucose Control With Palatinose-Based Alternative Sweeteners

Animal and clinical studies were performed to determine whether Palatinose-based alternative sweeteners with increased sweetness contributed to blood glucose elevations. In the animal study, male Sprague-Dawley rats (6 weeks old) received an oral load of 2 g of glucose or Palatinose-based alternative sweeteners per kilogram of body weight. Thirty minutes after the glucose load, the rat blood glucose levels in the Palatinose-based alternative sweetener groups were significantly lower than those in the glucose groups (p < 0.05). Palatinose-based alternative sweeteners significantly improved glucose tolerance in rats. However, significant differences in the blood glucose levels were not observed among the Palatinose-based alternative sweeteners. In the clinical study, 14 healthy volunteers (21.4 ± 1.3 years) consumed glucose or Palatinose-based alternative sweeteners (50 g). At 60 min, when Palatinose-based alternative sweeteners were ingested, blood glucose was significantly lower compared to when glucose was ingested (Palatinose-L, 123.1 mg/dL; Palatinose-IS, 125.9 mg/dL; Palatinose-FOS. 129.1 mg/dL vs. glucose, 154.8 mg/dL, p < 0.05). The glycaemic index of Palatinose-L, Palatinose-IS and Palatinose-FOS was 43.9, 58.1, and 49.2, respectively. Palatinose-based alternative sweeteners could help maintain health as the postprandial blood glucose levels are constantly maintained owing to slow hydrolysis.

Optimization of immobilized Lactobacillus pentosus cell fermentation for lactic acid production

Parametric optimization is an effective way in fermentation process to improve product yield and productivity in order to save time, space and financial resources. In this study, Box–Behnken design was applied to optimize the conditions for lactic acid production by immobilized Lactobacillus pentosus ATCC 8041 cell fermentation. Two quadratic models and response surface methodology were performed to illustrate the effect of each parameters and their interactions on the lactic acid yield and glucose consumption rate in immobilized L. pentosus ATCC 8041 cell fermentation. The maximum lactic acid yield was obtained as 0.938 ± 0.003 g/g glucose with a productivity of 2.213 ± 0.008 g/(L × h) under the optimized conditions of 2.0 mm bead diameter, 5.60 pH, 115.3 g/L initial glucose concentration, and 398.2 mg biomass (CDW) in 100 mL hydrogel. The analysis of variance indicated that the quadratic model was significant and could be used to scale up the fermentation process.

Performance analysis and optimization of ammonium removal in a new biological folded non-aerated filter reactor

A new type of biological folded non-aerated filter (BFNAF) was found to be superior and feasible for the treatment of NH₄⁺-N wastewater. It was constructed with the folded structure suitable for the nylon biomass carrier. The advantages of the BFNAF included low energy consumption, long reaction path, large biofilm surface area and non-clogging compared to the traditional biological aerated filter. In this study, the effects of hydraulic retention time (HRT), and the influent NH₄⁺-N concentration on the performance of BFNAF were investigated and optimized by the response surface methodology. Under the optimal operating condition (HRT, 10 h; NH₄⁺-N concentration, 52 mg/L), the removal efficiency and removal rate were 94.62 ± 0.63% and 0.106 kg-NH₄⁺ m^-3 day^-1, respectively. The results showed that the BFNAF reactor could remove NH₄⁺-N from wastewater and realized the nitrification process effectively under natural ventilation conditions.

Enhanced performance and microbial community analysis of bioelectrochemical system integrated with bio-contact oxidation reactor for treatment of wastewater containing azo dye

Feasibility and superiority of the bioelectrochemical system integrated with biocontact oxidation (BES-BCO) for degradation and/or mineralization of azo dyes have been confirmed. In this study, the effects of hydraulic retention time (HRT), applied voltage, and dissolved oxygen (DO) concentration at the bioanode on the performance of BES-BCO and traditional BES were investigated. Using the response surface methodology, the optimum values of HRT, applied voltage, and DO concentration at the bioanode of BES-BCO were investigated to obtain the maximum decolouration and COD removal efficiency and minimum specific energy consumption (SEC). The microbial community structure in BES-BCO was studied for analyzing the change following the introduction of oxygen. The optimised solution was an applied voltage of 0.59V, HRT of 12h, and DO concentration of 0.96mg/L at the bioanode. Under such conditions, the DE, COD removal efficiency, and SEC values were 94.62±0.63%, 89.12±0. 32%, and 687.57±3.86J/g, respectively. In addition, after changing from BES to BES-BCO, the bacterial community structure of the bioanode underwent significant changes. Several aerobic aniline-degrading bacteria and anode-respiration bacteria (ARB) were found to dominate the community of the anode biofilm. The results showed that the removal of azo dye degradation by-products was closely correlated with the o-bioanode and the BCO bacterial community structure.

Antifungal activities of anthocyanins from purple sweet potato in the presence of food preservatives

Effects of anthocyanins from purple sweet potato (APSP) against the fungal growth of Geotrichum candidum and Candida albicans were assessed. Response surface methodology was applied for optimization of proportions of sodium benzoate, potassium sorbate, and APSP. Optimum concentrations against G. candidum were 0.300 mg/mL of sodium benzoate, 0.290mg/mL of potassium sorbate, and 13.9mg/mL of APSP. Optimum concentrations against C. albicans were 0.380 mg/mL of sodium benzoate, 0.240 mg/mL of potassium sorbate, and 3.56 mg/mL of APSP. APSP exhibited enhanced antifungal properties in the presence of food preservatives.

Optimization of enhanced bioelectrical reactor with electricity from microbial fuel cells for groundwater nitrate removal

Factors influencing the performance of a continual-flow bioelectrical reactor (BER) intensified by microbial fuel cells for groundwater nitrate removal, including nitrate load, carbon source and hydraulic retention time (HRT), were investigated and optimized by response surface methodology (RSM). With the target of maximum nitrate removal and minimum intermediates accumulation, nitrate load (for nitrogen) of 60.70 mg/L, chemical oxygen demand (COD) of 849.55 mg/L and HRT of 3.92 h for the BER were performed. COD was the dominant factor influencing performance of the system. Experimental results indicated the undistorted simulation and reliable optimized values. These demonstrate that RSM is an effective method to evaluate and optimize the nitrate-reducing performance of the present system and can guide mathematical models development to further promote its practical applications.

Investigation and optimization of the novel UASB-MFC integrated system for sulfate removal and bioelectricity generation using the response surface methodology (RSM)

COD/sulfate ratio and hydraulic residence time (HRT), both of which influence sulfate loadings jointly, are recognized as the most two important affecting factors for sulfate removal and bioelectricity generation in the novel up-flow anaerobic sludge blanket reactor-microbial fuel cell (UASB-MFC) integrated system. The response surface methodology (RSM) was employed for the optimization of this system and the optimum condition with COD/sulfate ratio of 2.3 and HRT of 54.3h was obtained with the target of maximizing the power output. In terms of maximizing the total sulfate removal efficiency, the obtained optimum condition was COD/sulfate ratio of 3.7 and HRT of 55.6h. Experimental results indicated the undistorted simulation and reliable optimized results. These demonstrated that RSM was effective to evaluate and optimize the UASB-MFC system for sulfate removal and energy recovery, providing a promising guide to further improvement of the system for potential applications.

Biotechnological approaches for the production of prebiotics and their potential applications

Worldwide interest in prebiotics have been increasing extensively both as food ingredients and pharmacological supplements, since they have beneficial properties for human health. Prebiotics not only stimulate the growth of healthy bacteria such as bifidobacteria and lactobacilli in the gut but also increase the resistance towards pathogens. In addition to this, they also act as dietary fiber, an energy source for intestinal cells after converting to short-chain fatty acids, a stimulator of immune systems, sugar replacer etc. Moreover, due to heat resistant properties, they are able to maintain their intact form during the baking process and allow them to be incorporated into every day food products. Thus, they can be interesting and useful ingredients in the development of novel functional foods. This review provides comprehensive information about the different biotechnological techniques employed in the production of prebiotics and their potential applications in different areas.

Optimization of the extraction of anthocyanins from the fruit skin of Rhodomyrtus tomentosa (Ait.) Hassk and identification of anthocyanins in the extract using High-Performance Liquid Chromatography-Electrospray Ionization-Mass Spectrometry (HPLC-ESI-MS)

Anthocyanins are naturally occurring polyphenols that impart bright color to fruits, vegetables and plants. In this study, the extraction of anthocyanins from freeze-dried fruit skin of downy rose-myrtle (Rhodomyrtus tomentosa (Ait.) Hassk var. Gangren) was optimized using response surface methodology (RSM). Using 60% ethanol containing 0.1% (v/v) hydrochloric acid as extraction solvent, the optimal conditions for maximum yields of anthocyanin (4.358 ± 0.045 mg/g) were 15.7:1 (v/w) liquid to solid ratio, 64.38 °C with a 116.88 min extraction time. The results showed good fits with the proposed model for the anthocyanin extraction (R(2) = 0.9944). Furthermore, the results of high-performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS) analysis of the anthocyanins extracted from the fruit skin of downy rose-myrtle revealed the presence of five anthocyanin components, which were tentatively identified as delphinidin-3-glucoside, cyanidin-3-glucoside, peonidin-3-glucoside, petunidin-3-glucoside and malvidin-3-glucoside.

Extractive fermentation for enhanced production of thailandepsin A from Burkholderia thailandensis E264 using polyaromatic adsorbent resin Diaion HP-20

Thailandepsin A is natural product of Burkholderia thailandensis E264 with potent histone deacetylase inhibitory activities and promising anticancer activities. The titer of thailandepsin A is very low (less than 10 mg/l) from limited empirical fermentation. To facilitate preclinical evaluations and potentially clinical development of thailandepsin A, systematic optimization and extractive fermentation of thailandepsin A from B. thailandensis E264 culture in flasks were investigated in this pilot study. The main fermentation parameters—28°C, pH 7.0, inoculum ratio 1% (v/v), incubation duration 60 h, medium volume 26%, shaking speed 170 rpm, and chloroform as extracting solvent—were determined by single factor experiments. Polyaromatic adsorbent resin Diaion HP-20, when added at a concentration of 4% (w/v), was most effective to reduce feedback inhibition of thailandepsin A and to significantly increase the titer of target product. Central composite design was used to further optimize the fermentation medium for B. thailandensis E264. The optimized medium contains glucose 17.89 g/l, tryptone 34.98 g/l, potassium phosphate 24.84 g/l, and sodium citrate 0.01 g/l, which resulted in a large increase of the titer of thailandepsin A to 236.7 mg/l. Finally kinetic models based on the modified logistic and Luedeking–Piret equations were developed, delivering a good description of temporal variations of biomass, product, and substrate in the fermentation process, which could be used as references for developing large-scale fermentation.

Immobilization of Erwinia sp. D12 Cells in Alginate-Gelatin Matrix and Conversion of Sucrose into Isomaltulose Using Response Surface Methodology

Isomaltulose is a noncariogenic reducing disaccharide and also a structural isomer of sucrose and is used by the food industry as a sucrose replacement. It is obtained through enzymatic conversion of microbial sucrose isomerase. An Erwinia sp. D12 strain is capable of converting sucrose into isomaltulose. The experimental design technique was used to study the influence of immobilization parameters on converting sucrose into isomaltulose in a batch process using shaken Erlenmeyer flasks. We assessed the effect of gelatin and transglutaminase addition on increasing the reticulation of granules of Erwinia sp. D12 cells immobilized in alginate. Independent parameters, sodium alginate concentration, cell mass concentration, CaCl₂ concentration, gelatin concentration, and transglutaminase concentration had all a significant effect (P < 0.05) on isomaltulose production. Erwinia sp. D12 cells immobilized in 3.0% (w/v) sodium alginate, 47.0% (w/v) cell mass, 0.3 molL⁻¹ CaCl₂, 1.7% (w/v) gelatin and 0.15% (w/v) transglutaminase presented sucrose conversion into isomaltulose, of around 50–60% in seven consecutive batches.

High-density spore production of Piriformospora indica, a plant growth-promoting endophyte, by optimization of nutritional and cultural parameters

Piriformospora indica is an axenically cultivable root endophytic fungus which exerts plant growth promoting effects on its host plants. To enable commercial production of its spores, the medium composition and culture conditions have been optimized in a 14 L bioreactor such that they result in maximum biomass during growth phase and in maximum spore yield during subsequent sporulation phase. Maximum spore yields were obtained with modified Kaefer medium using a glucose deprivation strategy. An enhancement of 100% in overall biomass productivity (0.18 g L(-1) h(-1)) and reduction of about 70% in the time (60 h) required to achieve the maximum spore yield (9.25×10(7) spores/mL) was achieved in comparison to the original Kaefer medium. The high spore yield obtained in the present study seems to be economical for commercial production of P. indica.

Optimization of immobilization for selective oxidation of benzyl alcohol by Gluconobacter oxydans using response surface methodology

This study used the Box-Behnken design and response surface methodology to optimize immobilization of Gluconobacter oxydans in Ca-alginate gel for the production of benzaldehyde in a biphasic system. Immobilization parameters, such as Na-alginate concentration, cell load, and bead diameter, were optimized. The mathematical model developed was validated and proven to be statistically adequate and accurate in predicting the response. For both activity and stability responses, the best results were achieved at alginate concentration of 2.55% (w/v), cell load of 49.26 mg/ml, and 2.2 mm bead diameter. Under these conditions, retention activity of 87.6% could be attained for the immobilized cell. In addition, the oxidative activity of immobilized cells was retained at 53.2% compared with that of free cells after 10 repeated batch reactions, while only 15.7% of activity remained in free cells.

Production of cytidine 5'-diphosphorylcholine with high utilization of ATP by whole cells of Saccharomyces cerevisiae

Cytidine 5'-diphosphorylcholine (CDP-choline) was produced using a high efficiency ATP regeneration system and the Kennedy pathway in whole cells of Saccharomyces cerevisiae As 2.398. Out of eight variables, KH(2)PO(4), glycerol and (NH(4))(2)SO(4) were considered to be the most significant factors by response surface methodology including a Plackett-Burman design, path of steepest accent and central composite design. The optimum levels of the three variables were 20.13g/L KH(2)PO(4), 12.35g/L glycerol and 0.49g/L (NH(4))(2)SO(4), respectively. Energy utilization efficiency increased from 10.59% to 16.72% and choline chloride conversion yields increased from 12.35% to 42.78%. A high efficiency ATP regeneration system improves CDP-choline production.

Optimization of phenazine-1-carboxylic acid production by a gacA/qscR-inactivated Pseudomonas sp. M18GQ harboring pME6032Phz using response surface methodology

Phenazine-1-carboxylic acid (PCA) production was enhanced in Pseudomonas sp. M18 wild strain and its mutants carrying recombinant pME6032Phz for phz gene cluster overexpression, among which Pseudomonas sp. strain M18GQ/pME6032Phz, a gacA and qscR double gene chromosomally inactivated mutant harboring pME6032Phz, showed the highest PCA yield. The conditions for fermentation and isopropyl-beta-D-1-thiogalactopyranoside (IPTG) induction were optimized for strain M18GQ/pME6032Phz in shake flask experiments. A one-factor-at-a-time approach, followed by a fractional factorial design identified soybean meal, corn steep liquor, and ethanol as statistically significant factors. Optimal concentrations and mutual interactions of the factors were then determined by the method of steepest ascent and by response surface methodology based on the center composite design. The predicted PCA production was 6,335.2 mg/l after 60 h fermentation in the optimal medium of 65.02 g soybean meal, 15.36 g corn steep liquor, 12 g glucose, 21.70 ml ethanol, and 1 g MgSO(4) per liter in the flask fermentations, with induction of 1.0 mmol/l IPTG 24 h after inoculation. In an experimental validation under these conditions, the maximum PCA production was 6,365.0 mg/l. This represents a approximately 60% increase over production by strain M18GQ in optimal conditions. The negative effect of plasmid pME6032 on the expression of chromosomally located phz gene cluster was found in Pseudomonas sp. M18GQ, and the possible reason was discussed in the text.

Lactose nano-probe optimized using response surface methodology

A lactose nano-probe has been developed by immobilization of PsBGAL onto gold nanoparticles (AuNps). It is helpful for severe lactose intolerants for quality check of lactose hydrolyzed milk and estimation of hidden lactose present in variety of food products. Optimization of PsBGAL immobilization onto AuNps using spacer arm (cysteamine-glutaraldehyde) was carried out by response surface methodology (Box-Behnken design). The process has led to immobilization of enzyme onto AuNps with an efficiency of 140.81%. AuNp-PsBGAL was characterized using transmission electron microscopy, scanning electron microscopy and Fourier transform infrared spectroscopy. Immobilized enzyme showed broad temperature and pH optima and a significant enhancement in catalytic efficiency (V(max)/K(m)) with respect to soluble PsBGAL. AuNp-PsBGAL was stable under dried conditions than wet conditions for 6 months with loss of 10.2% and 87.53%, respectively. It has reusability of over five batchwise uses, with almost no loss in activity. Hill's coefficient was found to be 1.71 corresponding to lactose concentration ranging from 0.1% to 2.0%.

Optimization of the extraction of anthocyanin from Bokbunja (Rubus coreanus Miq.) marc produced during traditional wine processing and characterization of the extracts

The extraction of anthocyanin from Bokbunja (Rubus coreanus Miq.) marc generated during traditional wine processing was optimized using response surface methodology (RSM). A face-centered cube design (FCD) consisting of 17 experimental runs, including five replicates at the center point, was used to investigate the effects of the three variables (solid-liquid ratio, time, and temperature) on anthocyanin extraction, and the results showed that the relationship between the three variables and the total anthocyanin content followed a quadratic model (R2=0.8853). In addition, the RSM analysis predicted that the optimum conditions for extraction consisted of a solid-liquid ratio of 20, a time of 60min, and a temperature of 60 degrees C. Verification tests performed under these optimum conditions gave 34.7+/-1.4mg/100g of anthocyanin, which was close to predicted value of 37.2mg/100g. Additionally, analysis of water extracts prepared using the predicted optimum conditions revealed that the carbohydrates (sugar and pectin) in Bokbunja marc underwent significant variation toward the formation of by-products (glycerol and uronic acids) during yeast fermentation, and that the amount of anthocyanin produced was reduced 10-fold when compared to the original extraction. Further, the results of HPLC-PDA-MS/MS analysis of the anthocyanins extracted from Bokbunja marc revealed the presence of six anthocyanin components, which were tentatively identified as cyanidin 3-O-sambubioside, cyanidin 3-O-xylosylrutinoside, cyanidin 3-O-rutinoside, pelargonidin 3-O-rutinoside, delphinidin 3-O-rutinoside-?, and delphinidin 3-O-glucuronide.

Medium optimization for antifungal active substances production from a newly isolated Paenibacillus sp. using response surface methodology

Statistics based experimental designs were used to optimize the medium for antifungal active substances production from a newly isolated Paenibacillus polymyxa Cp-S316 in shaker flask cultivation. The medium components having significant effect on the production were first identified using a fractional factorial design. Then steepest ascent method was employed to approach the experimental design space, followed by an application of response surface methodology for further optimization. A quadratic model was found to fit the antifungal active substances production. Response surface analysis revealed that the optimum values of the tested variables for the production of active substances were 12.3 (g/l) lactose, 17.5 (g/l) peptone, 0.4 (g/l) sodium nitrate, 4.5 (g/l) magnesium sulfate and 100 (g/l) potato. A production of 4687.71microg/ml, which was in agreement with the prediction, was observed in verification experiment. In comparison to the production of basal medium, 3.05-fold increase had been obtained.