• Proceedings of the Korean Society for Applied Microbiology Conference
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• 2005.06a
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• pp.233-244
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• 2005

Guanosine fermentation process can be well predicted and analyzed by the proposed state equations describing the dynamic change of a bioreactor. Pyruvate and alanine were found to be characteristically accumulated along with the decline of the guanosine formation rate during the mid-late phase of the process. The enzymological study of the main pathways in glucose catabolism and the quantitative stoichiometric calculation of metabolic flux distribution revealed that it was entirely attributed to the shift of metabolic flux from hexose monophosphate (HMP) pathway to glycolysis pathway. The process optimization by focusing on the restore of the shift of metabolic flux was conducted and the overcoming the decrease of oxygen uptake rate (OUR) was taken as the relevant factor of the trans-scale operation. As a result, the production of guanosinewas increased from 17 g/L to over 34 g/I.

• Biotechnology and Bioprocess Engineering:BBE
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• v.11 no.2
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• pp.164-167
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• 2006

The influence of temperature and agitation on the growth of Escherichia coli expressing hepatitis B core antigen (HBcAg) in stirred tank bioreactor were investigated. The highest specific growth rate for E. coli$(0.844 h^{-1})$ was achieved at a temperature of $37^{\circ}C$ and an agitation speed of 250 rpm. The activation energy for the growth of the E. coli strain W3110lQ in the stirred tank bioreactor was estimated to be 11 kcal/mol. The highest protein yield was achieved at a temperature of $44^{\circ}C$ and an agitation speed of 250 rpm. The relative protein concentration at $44^{\circ}C$ is 30 and 6% higher compared to that at 30 and $37^{\circ}C$, respectively.

• Applied Biological Chemistry
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• v.50 no.1
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• pp.1-5
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• 2007

For the purpose of application for biomass of Pleurotus eryngii, the optimum culture condition were tested. It was found that the optimum culture condition for spot culture of pleurotus eryngii were 24$^{\circ}C$ for 18 days with PDA medium. And the optimum culture condition of bioreactor for biomass were pH 5.5, 18$^{\circ}C$ and 27 days with PDMP broth. It was possible to artificial cultivation of mycelial from Pleurotus eryngii using bioreactor for biomass under the optimum conditions, and it was also possible for Pleurotus eryngii biomass because the forming of fruiting body when Pleurotus eryngii was cultivated using mass artificial cultivated mycelial in the bioreactor.

• Journal of Microbiology and Biotechnology
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• v.32 no.9
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• pp.1178-1185
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• 2022

Steroids are a class of compounds with cyclopentane polyhydrophenanthrene as the parent nucleus, and they usually have unique biological and pharmacological activities. Most of the biosynthesis of steroids is completed by a series of enzymatic reactions starting from cholesterol. Synthetic biology can be used to synthesize cholesterol in engineered microorganisms, but the production of cholesterol is too low to further produce other high-value steroids from cholesterol as the raw material and precursor. In this work, combinational strategies were established to increase the production of cholesterol in engineered Saccharomyces cerevisiae RH6829. The basic medium for high cholesterol production was selected by screening 8 kinds of culture media. Single-factor optimization of the carbon and nitrogen sources of the culture medium, and the addition of calcium ions, zinc ions and citric acid, further increased the cholesterol production to 192.53 mg/l. In the 5-L bioreactor, through the establishment of strategies for glucose and citric acid feeding and dissolved oxygen regulation, the cholesterol production was further increased to 339.87 mg/l, which was 734% higher than that in the original medium. This is the highest titer of cholesterol produced by microorganisms currently reported. The fermentation program has also been conducted in a 50-L bioreactor to prove its stability and feasibility.

• Transactions on Control, Automation and Systems Engineering
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• v.4 no.4
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• pp.277-282
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• 2002

This paper proposes a nonlinear adaptive controller based on back-stepping method for tracking reference substrate concentration by manipulating dilution rate in a continuous baker's yeast cultivating process in stirred tank bioreactor. Control law is obtained from Lyapunov control function to ensure asymptotical stability of the system. The Haldane model for the specific growth rate depending on only substrate concentration is used in this paper. Due to the uncertainty of specific growth rate, it has been modified as a function including the unknown parameter with known bounded values. The substrate concentration in the bioreactor and feed line are measured. The deviation from the reference is observed when the external disturbance such as the change of the feed is introduced to the system. The effectiveness of the proposed controller is shown through simulation results in continuous system.

• KSBB Journal
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• v.27 no.1
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• pp.28-32
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• 2012

In this study, the treatment ability of the wastewater containing perchlorate by non-salt tolerant perchlorate reducing bacterial consortium (N-PRBC) was evaluated in a continuous stirred tank bioreactor (CSTR). To obtain the optimal operating condition the bioreactor was operated with the different wastewater empty bed retention time (EBRT). The treatment performance in the bioreactor could be maintained at 100 $mg-ClO_4{^-}L^{-1}$ up to a EBRT of 3 h, and the removal capacity in the CSTR was about 3.3 times higher than that in a batch operation. With a decrease from 9 h to 2 h in a EBRT, the volumetric perchlorate reduction rate was increased from 11.1 $mg-ClO_4{^-}L^{-1}h^{-1}$ to 50.0 $mg-ClO_4{^-}L^{-1}h^{-1}$, and the specific perchlorate reduction rates were increased from 3.01 $mg-ClO_4{^-}g-DCW^{-1}h^{-1}$. In conclusion, the treatment capacities in a CSTR were much better than those obtained in a batch operation.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.10
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• pp.679-684
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• 2014

Many burial sites were constructed to suppress the spread of foot and mouth disease during outbreak. Defected burial sites were removed when leachate leak is presumed and carcasses were moved to the circular storage tanks. However, carcasses were not decomposed possibly due to low water content, low microbial activities, and poor mixing. In this research, storage tank containing carcasses in it was modified to bioreactor to accelerate stabilization. Liquids with nutrients were added and circulated to maintain the optimum water content while extraneous microorganisms were augmented. Settlement was used as the primary index for assessing stabilization rate, and the consolidation theory was utilized to estimate the expected final settlement. 30% of carcasses is expected to be decomposed and removed from the storage tank for five years of bioreactor operation.

• Journal of Microbiology and Biotechnology
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• v.15 no.1
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• pp.1-6
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• 2005

Optimal criterion for the scale-up production of schizophyllan, a fungal polysaccharide secreted by Schizophyllum commune, was investigated. For the production of the polysaccharide in a 150-l bioreactor, the culture conditions optimized in a 15-l bioreactor were applied to a 150-l bioreactor with scale-up process, by changing impeller speed and airflow rate. The optimized impeller speed in the 15-l bioreactor was 50 rpm in a technical medium based on barley. For establishment of the scale-up process, 3 kinds of criteria were used while the gas throughput number was kept constant, as follows; constant volume-related power input, constant tip speed of stirrer, and constant Reynolds number. In the 150-l bioreactor, the highest values for the maximum specific growth rate (1.17/day) and productivity (0.63 g/L${\cdot}$day) were achieved in the culture condition from constant volumerelated power input criterion.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.11a
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• pp.281-282
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• 2008

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.943-944
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• 2012