• Journal of Microbiology and Biotechnology
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• 제30권10호
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• pp.1574-1582
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• 2020

Flavonoids have diverse biological functions in human health. All flavonoids contain a common 2-phenyl chromone structure (C6-C3-C6) as a scaffold. Hence, in using such a scaffold, plenty of high-value-added flavonoids can be synthesized by chemical or biological catalyzation approaches. (2S)-Naringenin is one of the most commonly used flavonoid scaffolds. However, biosynthesizing (2S)-naringenin has been restricted not only by low production but also by the expensive precursors and inducers that are used. Herein, we established an induction-free system to de novo biosynthesize (2S)-naringenin in Escherichia coli. The tyrosine synthesis pathway was enhanced by overexpressing feedback inhibition-resistant genes (aroG^fbr and tyrA^fbr) and knocking out a repressor gene (tyrR). After optimizing the fermentation medium and conditions, we found that glycerol, glucose, fatty acids, potassium acetate, temperature, and initial pH are important for producing (2S)-naringenin. Using the optimum fermentation medium and conditions, our best strain, Nar-17LM1, could produce 588 mg/l (2S)-naringenin from glucose in a 5-L bioreactor, the highest titer reported to date in E. coli.

• KSBB Journal
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• 제27권3호
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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.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1419-1426
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• 2008

Fulminant hepatic failure is a clinical syndrome associated with a high mortality rate. Orthotopic liver transplantation is the only clinically proven effective treatment for patients with end-stage liver disease who do not respond to medical management. A major limitation of this treatment modality is the scarcity of donor organs available, resulting in patients dying while waiting for a donor liver. An extracorporeal bioartificial liver (BAL) device containing viable hepatocytes has the potential to provide temporary hepatic support to liver failure patients, serving as a bridge to transplantation while awaiting a suitable donor. In some patients, providing temporary hepatic support may be sufficient to allow adequate regeneration of the host liver, thereby eliminating the need for a liver transplant. Although the BAL device is a promising technology for the treatment of liver failure, there are several technical challenges that must be overcome in order to develop systems with sufficient processing capacity and of manageable size. In this overview, the authors describe the critical issues involved in developing a BAL device. They also discuss their experiences in hepatocyte culture optimization within the context of a microchannel flat-plate BAL device.

• Advances in environmental research
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• 제9권2호
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• pp.109-121
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• 2020

Phenol is frequently present as the hazardous pollutant in petrochemical and pesticide industry wastewater. Because of its high toxicity and carcinogenic potential, a proper treatment is needed to reduce the hazards of phenol carrying effluent before being discharged into the environment. Phenol biodegradation with microbial consortium offers a very promising approach now a day's. This study focused on the formulation of phenol degrading bacterial consortium with three bacterial isolates. The bacterial strains Bacillus cereus strain VCRC B540, Bacillus cereus strain BRL02-43 and Oxalobacteraceae strain CC11D were isolated from detergent contaminated soil by soil enrichment technique and was identified by 16s rDNA sequence analysis. Individual cultures were degrade 100 μl phenol in 72 hrs. The formulated bacterial consortium was very effective in degrading 250 μl of phenol at a pH 7 with in 48 hrs. The study further focused on the analysis of the products of biodegradation with Fourier Transform Infrared Spectroscopy (FT/IR) and Gas Chromatography-Mass Spectroscopy (GC-MS). The analysis showed the complete degradation of phenol and the production of Benzene di-carboxylic acid mono (2-ethylhexyl) ester and Ethane 1,2- Diethoxy- as metabolic intermediates. Biodegradation with the aid of microorganisms is a potential approach in terms of cost-effectiveness and elimination of secondary pollutions. The present study established the efficiency of bacterial consortium to degrade phenol. Optimization of biodegradation conditions and construction of a bioreactor can be further exploited for large scale industrial applications.

• 한국미생물·생명공학회지
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• 제51권1호
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• pp.18-25
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• 2023

After random mutagenesis, the mutant Lactobacillus plantarum GNS300 showed improved exopolysaccharide production as determined by the quantification of total sugar. The mutant L. plantarum GNS300 produced 2.82 g/l of exopolysaccharide which showed 79.62% improved exopolysaccharide production compared with the parental strain. When exopolysaccharide of L. plantarum GNS300 was analyzed, the exopolysaccharide is composed of galactose (93.35%) and glucose (6.65%). Through the optimization of fermentation conditions using a bioreactor, 2.93 g/l of exopolysaccharide was produced from 20 g/l of glucose at 35℃, 500 rpm, and 0.1 vvm for 12 h. The mutant L. plantarum GNS300 exhibited 69.18% higher antioxidant activity than that from the parental strain, which might be caused by higher exopolysaccharide production. The concentrated supernatant of the mutant L. plantarum GNS300 inhibited the growth of gram-positive bacteria (Bacillus cereus and Staphylococcus aureus) and gram-negative bacteria (Escherichia coli, Vibrio parahaemolyticus, and Salmonella typhimurium).

• 한국식품과학회지
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• 제41권2호
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• pp.173-178
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• 2009

연속식 효소적 에스테르 교환반응을 이용하여 무-트랜스 유지를 제조하기 위한 체계적이고 입체적인 최적조건을 확립하기 위하여 3가지 독립변수($X_1$: 원료유지 중 FHCO 함량(%), $X_2$: 반응온도($^{\circ}C$), $X_3$: 기질의 흐름속도(mL/min))를 선정하여 RSM을 통해 각각의 독립변수에 대한 종속변수인 TS 전환율(Y)을 표현한 회귀방정식은 Y = 93.1146$(X_3)^2$+ 3.2387($X_1$) ($X_3$) + 2.6038($X_2$) ($X_3$)으로 나타났다. 이 방정식을 이용하여 정준분석을 이행한 결과 35%(w/w)의 FHCO를 함유한 원료유지를 사용하고 PBEB 내에서 68.67$^{\circ}C$의 온도 하에서 원료유지와 효소가 충분히 접촉할 수 있도록 0.63 mL/min의 흐름속도로 연속식 공정을 수행하면 TS 전환율이 극대화 되는 것으로 나타났다. 한편, 트랜스 지방의 함량이 높은 유지를 대체하되 실제 산업체 현장에서 생산되는 기존의 유지를 대체하기 위해서는 TS 전환율 뿐만 아니라 효소적으로 생산된 에스테르 교환 유지의 SFC 경향을 기존 유지의 결과와 비교하는 작업이 필요한데, 이때 비교대상의 기존 유지로는 트랜스 지방 함량 및 이화학적 물성 측면에서의 예비실험 결과 대체 가능성이 가장 높은 크림용 마가린(margarine)을 선정하였으며, 이러한 기존의 유지를 대체할 수 있는 무-트랜스 유지를 제조하기 위하여 SFC 경향 및 TS 전환율을 동시에 고려한 연속식 효소적 에스테르 교환반응의 최적조건을 확립하였으며, 최적조건은 42.83%(w/w)의 FHCO와 57.17%(w/w)의 SO가 혼합된 원료유지를 기질로 사용하며 PBEB 내에서의 반응온도는 64.72$^{\circ}C$이고, 효소와 원료유지가 극대로 접촉하여 효소적 에스테르 교환이 이루어질 수 있도록 기질의 흐름속도를 0.40 mL/min으로 각각 유지하는 것으로 판명되었다. 이상의 최적조건 하에서 연속식 효소적 에스테르 교환반응에 의해 제조된 유지의 SFC 경향을 분석하되 기존의 크림용 마가린의 경우와 비교한 결과 유의적으로 유사함을 확인하였으며, 이로써 본 논문에 의해 생산된 유지는 크림용 마가린을 성공적으로 대체할 수 있는 것으로 판단하였다. 또한, 반응온도를 60$^{\circ}C$ 및 55$^{\circ}C$로 각각 설정하여 2 단계로 분리한 PBEB에서의 TS전환율 변화를 측정한 결과, 반응 30일 경과시점까지 66%이상의 TS전환율을 유지하였으며(효소활성 반감기=약 30일 이상), 단일단계의 반응온도 실험(효소활성 반감기=약 15일)과 비교 시 반감기를 두 배 이상 연장할 수 있음을 확인하였다.

• 한국버섯학회지
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• 제6권1호
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• pp.27-31
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• 2008

현재까지 연구로는 흰목이 균사체에서 EPS 생산과 균사생장에 대한 적정 정치배양 조건이 연구되었다. 본 연구로부터 탄소원과 질소원의 처음 농도, 균사 형태와 발효조의 타입의 선택은 흰목이 균사체 EPS 생산에 가장 영향을 미친다는 것을 알게 되었다. 이들 결과는 공기주입식 반응기에서 EPS 생산성은 진탕탱크 반응기 보다 더 높았다는 점을 증명하였다. 또한 흰목이 균사의 정치배양의 생리적 생장에 대한 지식은 아직도 제한적이다.

• KSBB Journal
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• 제15권3호
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• pp.268-273
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• 2000

본 연구에서는 R rubrum을 이용한 석탄합성 가스로부터 수소 생산공정에 있어서의 세포성장 및 일산화탄소 전환을 최적화하 는 여러 조건들을 조사하였다. 그 중 pH의 영향을 살펴보면 R. rubrum 세포성장에는 pH 6~7이 최적이었고 수소생산에는 pH 7 7-7.5이 최적이었으며 pH가 5.5에서는 세포성장이거의 이루어 지지 않았다. 또한 온도가 34 'C 이상 증가되었을 때 세포성장이 둔화되어 멈추고 안정적인 co 전환속도를 얻을 수 없으므로 $30^{\circ}C$가 R. rubrum 균주 성장과 co 전환에 최적온도라 생각된다. 또한 R. rubrum은 photosynthetic bacteria인데 이 세포의 성장에 는 벚의 세기가 1,700-2,400 Lux가 최적임을 알 수 있었고 co 전환에는 계속적인 빛의 공급이 꼭 필요하지는 않고 간헐적인 빛의 노출만으로도 충분하다고 생각된다. 또한 연속반응기를 이 용하여 600 rpm, $30^{\circ}C$, pH 7에서 합성가스 체류시간 110분시 co 전환율 약 53%정도를 얻을 수 있었다. 이 연구가 계속 진 행되어져서 photobioreactor의 개발, high pressure bioreactor의 이 용, 균주의 mutatIOn 및 전환능력 우수 균주 등의 selection을 수 행한다면 매우 높은 합성가스 전환율을 갖는 생물반응기 공정개 발도 가능하리라 생각된다.

• 한국산업융합학회 논문집
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• 제4권3호
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• pp.243-251
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• 2001

The effects of various operating parameters(agitation speed, impeller type, antiform agents, impeller spacing etc.) on air-liquid mass transfer was characterized by volumetric mass transfer coefficient($k_La$). Also, the dual-impeller agitated systems are compared with single-impeller agitated systems with a special focus on its applications for bioreactors, $k_La$ was take over a range of 200~450 rpm of agitation speed, and 0.5~2.5 vvm of air flow rates, for four single impeller and impeller combinations consisting of four impeller types, namely rushton, pitched blade, scaba, intermig were tested. The rushton impeller showed the best $k_La$ as compared with other single impellers. The dual impeller system are found to be superior as compared to single impeller in all aspects, The best combination of the dual impeller was a intermig of axial flow type as an upper impeller and a rushton of radial flow type as a lower part. Also, the control of the DO level with the variation of agitation speed was more efficient than that with an increase in air flow rate. The addition of antiform dropped the $k_La$ very large up to 1g/L regardless the type. PPG was less effect on $k_La$ than other antiforms. The impeller spacing and presence of solute are found very effective on $k_La$. When the $NaNO_3$is presented as solute, the $k_La$ increased approximately 50% then control.

• Journal of Microbiology and Biotechnology
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• 제26권2호
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• pp.356-363
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• 2016

Human papillomavirus (HPV), a non-enveloped, double-stranded DNA tumor virus, is a primary etiological agent of cervical cancer development. As a potential tool for prophylactic vaccination, the development of virus-like particles (VLPs) containing the HPV16 L1 capsid protein is highly desired. In this study, we developed a high-level expression system of the HPV16 L1 in Escherichia coli for the purpose of VLP development. The native gene of HPV16 L1 has many rare codons that cause the early termination of translation and result in the production of truncated forms. First, we optimized the codon of the HPV16 L1 gene to the preferable codons of E. coli, and we succeeded in producing the full-size HPV16 L1 protein without early termination. Next, to find the best host for the production of HPV16 L1, we examined a total of eight E. coli strains, and E. coli BL21(DE3) with the highest yield among the strains was selected. With the selected host-vector system, we did a fed-batch cultivation in a lab-scale bioreactor. Two different feeding solutions (complex and defined feeding solutions) were examined and, when the complex feeding solution was used, a 6-fold higher production yield (4.6 g/l) was obtained compared with that with the defined feeding solution.