• Microbiology and Biotechnology Letters
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• v.17 no.3
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• pp.263-268
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• 1989

To maximize the performance of recombinant cell fermentation process through optimizing environmental conditions, the production of invertase from recombinant Saccharomyces cerebisiae Containing SUC2 gene was studied as a model. The recombinant cells showed biphasic growth on glucose. Since the promoter of the SUC2 is regulated by the concentration of glucose in the medium, expression of invertase by recombinant yeast began when the glucose concentration decreased in a range of 0.25-0.4 g/L during the batch culture. Plasmid segregation occured frequently during glucose fermentation, and infrequently during ethanol oxidation. A rapid appearance of invertase activity with glucose was observed under nonaerated condition, and the maximum specific invertase activity was about 1.5 times as high as under aerobic condition, In fed batch culture, when n low level of glucose was continuously supplied to the tormentor after the time of glucose depletion during growth phase, specific and total invertase activity increased about 1.7 and 2.9 fold, respectively, in a batch culture.

• KSBB Journal
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• v.13 no.5
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• pp.518-523
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• 1998

A large quantity of ethylene glycol(EG) is remained in the effluent after pretreating polyester weight-loss wastewater physicochemically in the fist stage and must be treated biologically in the second stage. Therefore, an excellent EG-utilizing bacteria strain was isolated from the natural system and the optimal culture conditions of the strain were investigated. The optimal culture conditions of temperature, pH, and nitrogen source were found to be 35$^{\circ}C$, 7.5 and ammonium chloride, respectively, when CODCr removal efficiency was more than 90%. The growth of stains and EG removal efficiency was slightly improved by adding elements such as niacin and biotin. With increasing inoculation size in a batch culture, the removal efficiency of EG was conspicuously increased. Growth rate was inhibited when the initial concentration of EG was more then 30g/L. The strain was identified as Pseudomonas sp. based on morphological and biological characteristics and named as Pseudomonas sp. EG1.

• 한국생물공학회:학술대회논문집
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• 2000.04a
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• pp.161-164
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• 2000

In hybridoma cell culture, $NH_4{^+}$ is the most important toxic byproduct so far identified. It has been postulated that $NH_4{^+}$, which is similar to $K^+$ in size, is taken up non-specifically by the cells through a potassium transport system, and that the addition of $K^+$ to the culture medium may have a detoxifying effect of $NH_4{^+}$. Thus, in this article the effects of high $K^+$ concentrations in the range of 10 mM to 60mM on hybridoma cell growth and metabolism were investigated. No significant differences in growth were found for $K^+$ concentrations up to 40 mM, but cell death in the death phase was slightly delayed in the cultures with $K^+$ addition. At 60mM, growth was initially poor but the cells could be adapted after approximately 13 passages. With similar growth levels for high $K^+$ concentrations having been Identified in batch cultivations using basal medium, we are currently investigating how such high levels of $K^+$ will affect cell growth in fortified batch cultures where the accumulation of $NH_4{^+}$ is more problematical.

• Journal of Microbiology and Biotechnology
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• v.5 no.4
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• pp.224-228
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• 1995

Fed-batch fermentations were conducted to produce human lipocortin-I (LC1), a potential anti-inflammatory agent, from recombinant Sacchromyces cerevisiae carrying a galactose-inducible expression system. The cell growth, expression level of LC1, and the plasmid stability were investigated under various LC1 induction modes performed by three different galactose feeding strategies. Galactoe was fed to induce the expression of LCl from the beginning (initial induction) of culture or when the cell concentration reached 120 OD (mid-phase induction) or 300 OD (late induction). Among the three galactose-induction modes tested, the initial induction mode yielded the best result with respect to a final expression level of LC1. Fedbatch fermentation with initial induction mode produced LC1 at a conentration of 220 mg/l, which corresponded to 1.38- and 1.53-fold increases over those produced by mid-phase and late induction modes.

• Journal of Microbiology and Biotechnology
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• v.17 no.7
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• pp.1183-1190
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• 2007

A metabolic uncoupler, 3,3',4',5-tetrachlorosalicylanilide (TCS), was used to reduce excess sludge production in biological wastewater treatment processes. Batch experiments confirmed that 0.4 mg/l of TCS reduced the aerobic growth yield of activated sludge by over 60%. However, the growth yield remained virtually constant even at the increased concentrations of TCS when cultivations were carried out under the anoxic condition. Reduction of sludge production yield was confirmed in a laboratory-scale anoxic-oxic process operated for 6 months. However, it was found that ammonia oxidation efficiency was reduced by as much as 77% in the presence of 0.8 mg/l of TCS in the batch culture. Similar results were also obtained through batch inhibition tests with activated sludges and by bioluminescence assays using a recombinant Nitrosomonas europaea (pMJ217). Because of this inhibitory effect of TCS on nitrification, the TCS-fed continuous system failed to remove ammonia in the influent. When TCS feeding was stopped, the nitrification yield of the process was resumed. Therefore, it seems to be necessary to assess the nitrogen content of wastewater if TCS is used for reducing sludge generation.

• Journal of Microbiology and Biotechnology
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• v.19 no.11
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• pp.1369-1373
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• 2009

Succinic acid was produced by continuous fermentation of Actinobacillus succinogenes sp. 130Z in an external membrane cell recycle reactor to improve viable cell concentration and productivity. Using this system, cell concentration increased to 16.4 g/l at the dilution rate $0.2\;h^{-1}$, up to 3 times higher than that of batch culture, and the volumetric productivity of succinic acid increased up to 6.63 g/l/h at the dilution rate $0.5\;h^{-1}$, 5 times higher than that of batch fermentation. However, in the continuous culture using a high dilution rate, operational problems including severe membrane fouling and contamination by lactic acid producer were observed. Another succinic acid producer, Mannheimia succiniciproducens MBEL55E, was also utilized in this system, and the cell concentration and productivity of succinic acid at the dilution rate of $0.3\;h^{-1}$ were found to be above 3 and 2.3 times higher, respectively, compared with those obtained at the dilution rate of $0.1\;h^{-1}$. These observations give a deep insight into the process design for a continuous succinic acid production by microorganisms.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.25 no.3
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• pp.237-243
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• 2016

Recently, technologies that produce biofuels from microalgae are being studied worldwide. It is necessary to significantly reduce the production costs of biofuels from microalgae for economic reasons. In this study, the growth curve of the microalgae was obtained using the batch-culture method, and the specific growth rate was predicted using the regression method. Based on the culture conditions of the estimated specific growth rate, the turbidity of the microalgae in the flat panel photobioreactor (PBR) was measured. Furthermore, an on-off control scheme was applied to the flat panel PBR in order to culture the microalgae continuously on the basis of turbidity. The parameters of the on-off control system were displayed by LabView. The on-off scheme of peristaltic pump was controlled based on the turbidity in the PBR. In addition, the turbidity values of growth curves were compared and analyzed in the continuous culture process using the on-off controller.

• Journal of Microbiology
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• v.35 no.2
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• pp.123-126
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• 1997

The aim of the present study was to optimize culture condition for the expression of lipocortin-1$_{1-185}$ in a recombinant of Escherichia coli using batch system. Plasmid (pHT22) carrying lipocortin-1$_{1-185}$ gene was well maintained in the recombinant with the addition of amplicillin as a selection pressures. Optimum temperature was 28$^{\circ}C$ for seed culture and 4$0^{\circ}C$ for main culture and the optimum pH was 7.0. The production of Lipocortin-1$_{1-185}$ was closely associated with cell growth and related to plasmid amplification.

• KSBB Journal
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• v.5 no.3
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• pp.307-313
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• 1990

A microcomputer-aided fermentation system was constructed for high density fed-batch culture using dissolved oxygen(DO) as a substrate feeding indicator. DO signal was processed prior to aquisition to computer. Agitation speed and oxygen flow rate was changed stepwisely to maintain DO value at a constant level. Agitation speed was controlled by the output signal of D/A converter. Oxygen flow rate was controlled by a flow rate control valve connected to a stepping motor. Substrate was fed with a feeding pump operated by the abrupt increase of DO signal. Methylobacillus sp. SK1 was cultivated to test the system and 16.53g/l of cell density was obtained after 10 hr.

• Environmental Engineering Research
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• v.15 no.1
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• pp.3-7
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• 2010

To better understand the ecology of tetrade forming organisms (TFOs) floating in a large amount of dairy wastewater treatment plant (WWTP) effluent (sequencing batch reactor [SBR]) during the inefficient phosphorus (P) removal process of an enhanced biological P removal system, the TFOs from the effluent of a full scale WWTP were separated and attempts made to culture the TFOs in presence/absence of oxygen. The intact TFOs only grew aerobically in the form of unicellular short-rods. Furthermore, to identify the intact TFOs and unicellular short-rods the DNAs of both were extracted, analyzed using their denaturing gradient gel electrophoresis (DGGE)-profiles and then sequenced. The TFOs and unicellular short-rods exhibited the same banding pattern in their DGGE-profiles, and those sequencing data resulted in their identification as Acinetobacter sp. The intact TFOs appeared in clumps and packages of tetrade cells, and were identified as Acinetobacter sp., which are known as strict aerobes and efficient P-removers. The thick layer of extracellular polymeric substance surrounding Acinetobacter sp. may inhibit phosphate uptake, and the cell morphology of TFOs might subsequently be connected with their survival strategy under the anaerobic regime of the SBR system.