• Journal of Microbiology and Biotechnology
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• v.22 no.7
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• pp.923-929
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• 2012

Optimization of culture conditions for L-asparaginase production by submerged fermentation of Aspergillus terreus MTCC 1782 was studied using a 3-level central composite design of response surface methodology and artificial neural network linked genetic algorithm. The artificial neural network linked genetic algorithm was found to be more efficient than response surface methodology. The experimental $_L$-asparaginase activity of 43.29 IU/ml was obtained at the optimum culture conditions of temperature $35^{\circ}C$, initial pH 6.3, inoculum size 1% (v/v), agitation rate 140 rpm, and incubation time 58.5 h of the artificial neural network linked genetic algorithm, which was close to the predicted activity of 44.38 IU/ml. Characteristics of $_L$-asparaginase production by A. terreus MTCC 1782 were studied in a 3 L bench-scale bioreactor.

• Journal of Microbiology and Biotechnology
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• v.24 no.1
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• pp.97-105
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• 2014

Quorum quenching (QQ) with a microbial vessel has recently been reported as an economically feasible biofouling control platform in a membrane bioreactor (MBR) for wastewater treatment. In this study, a quorum quenching MBR with a ceramic microbial vessel (CMV) was designed to overcome the extremely low F/M ratio inside a microbial vessel. The CMV was prepared with a monolithic ceramic microporous membrane and AHL-degrading QQ bacteria, Pseudomonas sp. 1A1. The "inner flow feeding mode" was introduced, under which fresh feed was supplied to the MBR only through the center lumen in the CMV. The inner flow feeding mode facilitated nutrient transport to QQ bacteria in the CMV and thus enabled relatively long-term maintenance of cell viability. The quorum quenching effect of the CMV on controlling membrane biofouling in the MBR was more pronounced with the inner flow feeding mode, which was identified by the slower increase in the transmembrane pressure as well as by the visual observation of a biocake that formed on the used membrane surface. In the QQ MBR with the CMV, the concentrations of extracellular polymeric substances were substantially decreased in the biocake on the membrane surface compared with those in the conventional MBR. The CMV also showed its potential with effective biofouling control over long-term operation of the QQ MBR.

• Journal of Korean Society on Water Environment
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• v.33 no.2
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• pp.140-148
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• 2017

An important factor in determining the design and treatment efficiency of wastewater treatment plants (WWTPs) is the quantity and quality of influent. These detailed and accurate information is essential for process control, diagnosis and operation, as well as the basis in designing the plant, selecting the process and determining the optimal capacity of each bioreactor. Probabilistic models are used to predict the wastewater quantity and quality of WWTPs, which are widely used to improve the design and operation of WWTPs. In this study, the optimal probability distribution of time series influent data was derived for predicting water quantity and quality, and wastewater influent data were generated using the Monte Carlo simulation analysis. In addition, we estimated various alternatives for the improvement of bioreactor operations based on present operation condition using the generated influent data and activated sludge model, and suggested the alternative that can operate the most effectively. Thus, the influent quantity and quality are highly correlated with the actual operation data, so that the actual WWTPs influent characteristics were well reproduced. Using this will improve the operating conditions of WWTPs, and a proposed improvement plan for the current TMS (Tele Monitoring System) effluent quality standards can be made.

• Journal of Microbiology and Biotechnology
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• v.22 no.2
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• pp.199-206
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• 2012

Naturally immobilized tannase (tannin acyl hydrolase, E.C. 3.1.1.20) has many advantages, as it avoids the expensive and laborious operation of isolation, purification, and immobilization, plus it is highly stable in adverse pH and temperature. However, in the case of cell-associated enzymes, since the enzyme is associated with the biomass, separation of the pure biomass is necessary. However, tannic acid, a known inducer of tannase, forms insoluble complexes with media proteins, making it difficult to separate pure biomass. Therefore, this study optimizes the production of cell-associated tannase using a "protein-tannin complex" free media. An exploratory study was first conducted in shake-flasks to select the inducer, carbon source, and nitrogen sources. As a result it was found that gallic acid induces tannase synthesis, a tryptose broth gives higher biomass, and lactose supplementation is beneficial. The medium was then optimized using response surface methodology based on the full factorial central composite design in a 3 l bioreactor. A $2^3$ factorial design augmented by 7 axial points (${\alpha}$ = 1.682) and 2 replicates at the center point was implemented in 17 experiments. A mathematical model was also developed to show the effect of each medium component and their interactions on the production of cell-associated tannase. The validity of the proposed model was verified, and the optimized medium was shown to produce maximum cell-associated tannase activity of 9.65 U/l, which is 93.8% higher than the activity in the basal medium, after 12 h at pH 5.0, $30^{\circ}C$. The optimum medium consists of 38 g/l lactose, 50 g/l tryptose, and 2.8 g/l gallic acid.

• Transactions of the Korean hydrogen and new energy society
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• v.15 no.2
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• pp.166-174
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• 2004

Purple non-sulfur bacteria, Rhodobacter sphaeroides KD131 grew to reach the maximum cell concentration in 45 hrs of incubation in the synthetic media containing (NH4)2SO4, L-aspartic acid and succinic acid as the carbon and nitrogen sources, respectively, at 30oC under 8 klux irradiance using halogen lamp. The strain produced hydrogen from the middle of the logarithmic growth phase and continued until the cell growth leveled out. The strain grew and produced hydrogen under the irradiance of 3-30 klux, but cell growth was inhibited over 100 klux. In addition, anaerobic/light culture condition was better than the aerobic/dark on the hydrogen production. Among various photo-bioreactors examined, the flat-vertical reactor manufactured using clear acrylic plastic material showed the best hydrogen production rate at the given culture condition.

• 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.31 no.5
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• pp.717-725
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• 2021

This study aimed to optimize medium composition and culture conditions for enhancing the biomass of Lactobacillus plantarum 200655 using statistical methods. The one-factor-at-a-time (OFAT) method was used to screen the six carbon sources (glucose, sucrose, maltose, fructose, lactose, and galactose) and six nitrogen sources (peptone, tryptone, soytone, yeast extract, beef extract, and malt extract). Based on the OFAT results, six factors were selected for the Plackett-Burman design (PBD) to evaluate whether the variables had significant effects on the biomass. Maltose, yeast extract, and soytone were assessed as critical factors and therefore applied to response surface methodology (RSM). The optimal medium composition by RSM was composed of 31.29 g/l maltose, 30.27 g/l yeast extract, 39.43 g/l soytone, 5 g/l sodium acetate, 2 g/l K₂HPO₄, 1 g/l Tween 80, 0.1 g/l MgSO₄·7H₂O, and 0.05 g/l MnSO₄·H₂O, and the maximum biomass was predicted to be 3.951 g/l. Under the optimized medium, the biomass of L. plantarum 200655 was 3.845 g/l, which was similar to the predicted value and 1.58-fold higher than that of the unoptimized medium (2.429 g/l). Furthermore, the biomass increased to 4.505 g/l under optimized cultivation conditions. For lab-scale bioreactor validation, batch fermentation was conducted with a 5-L bioreactor containing 3.5 L of optimized medium. As a result, the highest yield of biomass (5.866 g/l) was obtained after 18 h of incubation at 30℃, pH 6.5, and 200 rpm. In conclusion, mass production by L. plantarum 200655 could be enhanced to obtain higher yields than that in MRS medium

• Microbiology and Biotechnology Letters
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• v.48 no.3
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• pp.344-357
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• 2020

Strain improvement and bioprocess development were undertaken to enhance hyaluronic acid(HA) production by Streptococcus zooepidemicus cells. Using a high-yielding mutant strain, statistical medium optimization was carried out in shake flask cultures, resulting in 52% increase in HA production (5.38 g/l) at the optimal medium composition relative to the parallel control cultures. For sufficient supply of dissolved oxygen (DO), which turned out to be crucial for enhanced production of HA, agitation system and speed were intensively investigated in 5 L bioreactor cultures. Increase in oxygen mass transfer coefficient (k_La) through increment of agitation speed (rpm) and 35% expansion of diameter of the newly-designed impellers showed significantly positive effects on HA production. By installing an expanded Rushton-turbine impeller for efficient break-down of sparged air, and an extended marine impeller above the Rushton-turbine impeller for efficient mixing of the air-born viscous fermentation broth, maximum amount of HA (9.79 g/l) was obtained at 450 rpm, 1.8 times higher level than that of the corresponding flask culture. Subsequently, the possibility of bioprocess scale-up to a 50 L bioreactor was investigated. Despite almost identical maximum HA production (9.11 vs 9.25 g/l), the average HA volumetric productivity (r_p) of the 50 L culture turned out only 74% compared to the corresponding 5 L culture during the exponential phase, possibly caused by shear damages imposed on the producing cells at the high stirring in the 50 L culture. The scale-up process could be successfully achieved if a scale-up criterion of constant oxygen mass transfer coefficient (k_La) is applied to the 50 L pilot-scale bioreactor system.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.6
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• pp.870-877
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• 2023

The purpose of this study was to assess the efficiency of nitrification based on ammonia loading rates and hydraulic air-loading rates in a moving bed bioreactor (MBBR) under seawater conditions. The goal was to provide foundational data for the design of these bio reactors. At an ammonia loading rate of 0.2 g TAN·m^-2 surface area·day^-1, the influent TAN concentration was determined to be 1.76±0.33 mg·L^-1, which is below the safe concentration for fish survival (2 mg·L^-1). Considering operational aspects, the optimal ammonia-loading rate was derived. Subsequently, experimental results for nitrification efficiency at the optimal ammonia-loading rate revealed that the optimum hydraulic air-loading rate was 1.8 L·air·m^-2 surface area·min^-1. This condition resulted in the lowest concentrations of TAN and NO₂-N in the influent water, thus establishing the optimal hydraulic air-loading rate. A regression equation was derived for the ammonia-removal rate (Y) based on the ammonia-loading rate (x) and expressed as a 0.5-order equation (Y=ax^0.5+b). Specifically, for TAN concentrations of 0-6 mg·L-1, the regression equation Y=0.1683x^0.5-0.13628, was established.

• KSBB Journal
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• v.27 no.3
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• pp.186-194
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• 2012

Various human host cell lines, which are more effective than the other original human cell lines, have been developed and used. Highly efficient human cell line can be obtained from the fusion between human embryonic kidney 293 (HEK293) and human Burkitt's lymphoma cells (Namalwa). Fused cell line has the advantages of both cell lines such as the high transfection efficacy of HEK293 cells and the constitutive expression of Epstein-Barr virus (EBV) genome which is related with high expression of target protein and anti-apoptotic growth of Namalwa cells. In this study, characterization of two original cell lines was performed by using design of experiment (DOE) considering cell maintenance, media development, optimization of culture condition, and scale-up. The formation of aggregates was apparent with high glutamine concentration at more than 6 mM. Supplementation of hydrolysates showed positive effects on the growth performances of HEK293 cells. On the contrary, Namalwa cells showed negative results. It was confirmed that Namalwa cells were more sensitive to lower temperature at $35^{\circ}C$ and hyperosmotic condition over 260 mOsm/kg. In addition, both cell lines showed limited growth in 3-L bioreactor due to shear stress.