• Journal of Microbiology and Biotechnology
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• v.21 no.9
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• pp.960-967
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• 2011

Tannin acyl hydrolase, also known as tannase, is an enzyme with important applications in the food, feed, pharmaceutical, and chemical industries. However, despite a growing interest in the catalytic properties of tannase, its practical use is very limited owing to high production costs. Several studies have already demonstrated the advantages of solid-state fermentation (SSF) for the production of fungal tannase, yet the optimal conditions for enzyme production strongly depend on the microbial strain utilized. Therefore, the aim of this study was to improve the tannase production by a locally isolated A. niger strain in an SSF system. The SSF was carried out in packed-bed bioreactors using polyurethane foam as an inert support impregnated with defined culture media. The process parameters influencing the enzyme production were identified using a Plackett-Burman design, where the substrate concentration, initial pH, and incubation temperature were determined as the most significant. These parameters were then further optimized using a Box-Behnken design. The maximum tannase production was obtained with a high tannic acid concentration (50 g/l), relatively low incubation temperature ($30^{\circ}C$), and unique low initial pH (4.0). The statistical strategy aided in increasing the enzyme activity nearly 1.97-fold, from 4,030 to 7,955 U/l. Consequently, these findings can lead to the development of a fermentation system that is able to produce large amounts of tannase in economical, compact, and scalable reactors.

• Journal of Microbiology and Biotechnology
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• v.29 no.6
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• pp.933-943
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• 2019

Gamma-aminobutyric acid (GABA)-producing strains were isolated from four edible insects and subjected to 16S rRNA sequence analysis. Among the four GABA-producing bacteria, Enterococcus avium JS-N6B4 exhibited the highest GABA-production, while cultivation temperature, initial pH, aerobic condition, and mono-sodium glutamate (MSG) feeding were found to be the key factors affecting GABA production rate. The culture condition was optimized in terms of glucose, yeast extract, and MSG concentrations using response surface methodology (RSM). GABA production up to 16.64 g/l was obtained under the conditions of 7 g/l glucose, 45 g/l yeast extract, and 62 g/l MSG through the optimization of medium composition by RSM. Experimental GABA production was 13.68 g/l, which was close to the predicted value (16.64 g/l) calculated from the analysis of variance, and 2.79-fold higher than the production achieved with basic medium. Therefore, GABA-producing strains may help improve the GABA production in edible insects, and provide a new approach to the use of edible insects as effective food biomaterials.

• Journal of Microbiology and Biotechnology
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• v.32 no.7
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• pp.892-901
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• 2022

The rising demand for carotenoids can be met by microbial biosynthesis as a promising alternative to chemical synthesis and plant extraction. Several species of lactic acid bacteria (LAB) specifically produce C₃₀ carotenoids and offer the added probiotic benefit of improved gut health and protection against chronic conditions. In this study, the recently characterized Lactiplantibacillus plantarum subsp. plantarum KCCP11226^T produced the rare C₃₀ carotenoid, 4,4'-diaponeurosporene, and its yield was optimized for industrial production. The one-factor-at-a-time (OFAT) method was used to screen carbon and nitrogen sources, while the abiotic stresses of temperature, pH, and salinity, were evaluated for their effects on 4,4'-diaponeurosporene production. Lactose and beef extract were ideal for optimal carotenoid production at 25℃ incubation in pH 7.0 medium with no salt. The main factors influencing 4,4'-diaponeurosporene yields, namely lactose level, beef extract concentration and initial pH, were enhanced using the Box-Behnken design under response surface methodology (RSM). Compared to commercial MRS medium, there was a 3.3-fold increase in carotenoid production in the optimized conditions of 15% lactose, 8.3% beef extract and initial pH of 6.9, producing a 4,4'-diaponeurosporene concentration of 0.033 A₄₇₀/ml. To substantiate upscaling for industrial application, the optimal aeration rate in a 5 L fermentor was 0.3 vvm. This resulted in a further 3.8-fold increase in 4,4'-diaponeurosporene production, with a concentration of 0.042 A₄₇₀/ml, compared to the flask-scale cultivation in commercial MRS medium. The present work confirms the optimization and scale-up feasibility of enhanced 4,4'-diaponeurosporene production by L. plantarum subsp. plantarum KCCP11226^T.

• Journal of Electrochemical Science and Technology
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• v.15 no.3
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• pp.388-404
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• 2024

In the present work, the operating parameters were optimized using Box Behnken Design (BBD) in response surface methodology (RSM) to maximize the hydrogen production rate (R₁) and hydrogen production rate per unit watt consumed (R₂) of a proton exchange membrane electrolysis cell (PEMEC), a third response (R₃) which was the sum of the scaled values of R₁ and R₂ were selected to be maximized so that both hydrogen production rate and hydrogen production rate per unit watt consumed could be maximized. The major parameters which were influencing the experiment for enhancing the output responses were oxygen electrode/anode electrocatalyst loading (A), current supplied (B) and water inlet temperature (C). The commercial proton exchange membrane Nafion^® was used as the electrolyte. The acetylene black carbon (C_AB) supported IrO₂ was used as the electrocatalyst for preparing oxygen electrode/anode whereas commercial Pt (40 wt%)/C_HSA was used as the H₂ electrode/cathode electrocatalyst. The quadratic model was developed to predict the output/ responses and their proximity to the experimental output values. The developed model was found to be significant as the P values for both the responses were < 0.0001 and F values were greater than 1. The optimum condition for both the responses were O₂ electrode/anode electrocatalyst loading of 1.78 mg/cm², supplied current of 0.33 A and water inlet temperature of 54℃. The predicted values for hydrogen production rate (R₁) and hydrogen production rate per unit watt consumed (R₂) were 2.921 mL/min and 2.562 mL/(min·W), respectively obtained from the quadratic model. The error % between the predicted response values and experimental values were 1.47% and 3.08% for R₁ and R₂, respectively. This model predicted the optimum conditions reasonably in good agreement with the experimental conditions for the enhancement of the output responses of the developed PEM based electrolyser.

• Korean Chemical Engineering Research
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• v.46 no.5
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• pp.903-914
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• 2008

This study was undertaken for the production capacity expansion and energy saving through entire process simulation and optimization for the commercial process of manufacturing monoethylene glycol as a staple from ethylene oxide. Aspen $Plus^{TM}$(ver. 2006) was employed in the simulation and optimization work. The multicomponent vapor-liquid equilibria involved in the process were calculated using the NRTL-RK equation. As for the binary interaction parameters required for a total of 91 binary systems, those for 8 systems were self-supplied by the simulator, those for 28 systems were estimated through regression of the VLE data in the literature, and the remainder were estimated with the estimation system built in the simulator. Subsequent to ascertaining the accuracy of the generated parameters through comparison between actual and simulated process data, sensitive variables highly affecting the process were searched and selected using sensitivity analysis tool in the simulator. The optimum operating conditions minimizing the total heat duty of the process were investigated using the optimization tool based on the successive quadratic programming in the simulator.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.5
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• pp.543-551
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• 2011

The paper deals with the comparative study of design optimization based on various approximation techniques in strength design of riser support structure installed on floating production storage and offloading unit(FPSO) using offshore operation loading conditions. The design optimization problem is formulated such that structural member sizing variables are determined by minimizing the weight of riser support structure subject to the constraints of structural strength in terms of loading conditions. The approximation techniques used in the comparative study are response surface method based sequential approximate optimization(RBSAO), Kriging based sequential approximate optimization(KBSAO), and the enhanced moving least squares method(MLSM) based approximate optimization such as CF(constraint feasible)-MLSM and Post-MLSM. Commercial process integration and design optimization(PIDO) tools are employed for the applications of RBSAO and KBSAO. The enhanced MLSM based approximate optimization techniques are newly developed to ensure the constraint feasibility. In the context of numerical performances such as design solution and computational cost, the solution results from approximate techniques based design optimization are compared to actual non-approximate design optimization.

• The Journal of Fisheries Business Administration
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• v.43 no.1
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• pp.1-9
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• 2012

Based on Clark and Munro's theory of dynamic optimization between fishery resources and production, this study is aimed to take an empirical analysis of optimal production level to the Danish Seine fishery under the sandfish stock rebuilding plan. For empirical analysis, it examined the optimal fish stock size, production and fishing effort levels and it also made an additional evaluation of optimal production changes on main variables by sensitivity analyses. When a 4% of the discount rate is assumed, the optimal sandfish production of Danish Seine fishery would be 3,049 t, and the sandfish optimal stock size is evaluated to be 19,016 t. In addition, the optimal fishing effort is estimated to be 4,368 days. Accordingly, to achieve the optimal production level, current fishing efforts should be reduced while the fish stock size should be increased up to the optimal level.

• Journal of Hydrogen and New Energy
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• v.19 no.1
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• pp.41-48
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• 2008

Fermentative $H_2$ production was studied using microbial consortia isolated from heat-treated ($90{\circ}C$, 20 min) sewage sludge. Important parameters investigated were carbon(C) and nitrogen(N)-sources, C/N ratio, phosphate concentration, pH and temperature during anaerobic cultivation in serum bottles. Starch, ribose, sucrose and glucose were good C-sources for the culture growth and $H_2$ production. Yeast extract was better N-source than $(NH_4)_2SO_4$ or peptone when individually added to the synthetic media, however the combination of above three N-sources exhibited the additional effect for cell growth and $H_2$ evolution. Addition of 100 mM phosphate as a buffering agent prevented the rapid pH drop during the cultivation. The optimum initial pH for the cell growth was at 7.0, whereas $H_2$ production was observed at pH 5.5. Optimum temperature for the cell growth and $H_2$ production was $37{\circ}C$. Initial C/N ratio of 1.22 in the media using glucose and yeast extract as the C- and N-sources, respectively, showed the $H_2$ yield 1.0 mol $H_2$/mol glucose.

• IE interfaces
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• v.16 no.3
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• pp.280-290
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• 2003

Many firms are trying to optimize their production and distribution functions separately, but possible savings by this approach may be limited. Nowadays, it is more important to analyze these two functions simultaneously by trading off the costs associated with the whole. In this paper, I treat a production and distribution planning problem for single-period inventory products comprised of a single production facility and multiple customers, with the aim of optimally coordinating important and interrelated decisions of production sequencing and vehicle routing. Then, I propose a hybrid genetic algorithm incorporating several local optimization techniques, HGAP, for integrated production-distribution planning. Computational results on test problems show that HGAP is effective and generates substantial cost savings over Hurter and Buer's decoupled planning approach in which vehicle routing is first developed and a production sequence is consequently derived. Especially, HGAP performs better on the problems where customers are dispersed with multi-item demand than on the problems where customers are divided into several zones based on single-item demand.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.1
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• pp.28-32
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• 2023

We optimized ultrasound-assisted extraction to improve the extraction efficiency of bioactive compounds from the microalgae Acutodesmus reginae. To optimize this extraction process, we investigated the effects of solvent type, solvent concentration, extraction time, extraction number, and extraction power on the production of lutein, α-carotene, β-carotene, and chlorophylls a, and b. After sequential optimization of these main variables, the maximum amount of each compound was extracted at 30℃ with an ultrasound power of 80 W and using 99.5% methanol. Under these optimum conditions, the amount of lutein, α-carotene, β-carotene, and chlorophylls a, and b, were measured as 10.43, 8.66, 3.76, 15.43, and 6.39 mg/g dry matter respectively.