-
[show abstract]
[hide abstract]
ABSTRACT: Fed-batch cultures of Hansenula polymorpha were studied to develop an efficient biosystem to produce recombinant human serum albumin (HSA). To comply with this purpose, we used high purity oxygen supplying strategy to increase viable cell density in a bioreactor and enhance the production of target protein. A mutant strain, H. polymorpha GOT7 was utilized in this study as a host strain in both 5-L and 30-L scale fermentors. To supply high purity oxygen into a bioreactor, nearly 100 % high purity oxygen from commercial bomb or higher than 93 % oxygen available in-situ from a pressure swing adsorption oxygen generator (PSA) was employed. Under the optimal fermentation of H. polymorpha with high purity oxygen, the final cell densities and produced HSA concentrations were 24.6 g/L and 5.1 g/L in the 5-L fermentor, and 24.8 g/L and 4.5 g/L in the 30-L fermentor, respectively. These were about 2-10 times higher than those obtained in air-based fed-batch fermentations. The discrepancies between the 5-L and 30-L fermentors with air supply were presumably due to the higher contribution of surface aeration over submerged aeration in the 5-L fermentor. This study, therefore, proved the positive effect of high purity oxygen to enhance viable cell density as well as target recombinant protein production in microbial fermentations.
Journal of Microbiology and Biotechnology 11/2010; 20(11):1534-8. · 1.38 Impact Factor
-
Jinwoo Lee,
Youjin Lee, Jong Kyu Youn,
Hyon Bin Na,
Taekyung Yu,
Hwan Kim,
Sang-Mok Lee,
Yoon-Mo Koo,
Ja Hun Kwak,
Hyun Gyu Park,
Ho Nam Chang,
Misun Hwang,
Je-Geun Park,
Jungbae Kim,
Taeghwan Hyeon
[show abstract]
[hide abstract]
ABSTRACT: Uniformly sized silica-coated magnetic nanoparticles (magnetite@silica) are synthesized in a simple one-pot process using reverse micelles as nanoreactors. The core diameter of the magnetic nanoparticles is easily controlled by adjusting the w value ([polar solvent]/[surfactant]) in the reverse-micelle solution, and the thickness of the silica shell is easily controlled by varying the amount of tetraethyl orthosilicate added after the synthesis of the magnetite cores. Several grams of monodisperse magnetite@silica nanoparticles can be synthesized without going through any size-selection process. When crosslinked enzyme molecules form clusters on the surfaces of the magnetite@silica nanoparticles, the resulting hybrid composites are magnetically separable, highly active, and stable under harsh shaking conditions for more than 15 days. Conversely, covalently attached enzymes on the surface of the magnetite@silica nanoparticles are deactivated under the same conditions.
Small 02/2008; 4(1):143-52. · 8.35 Impact Factor
-
Jinwoo Lee Dr,
Youjin Lee, Jong Kyu Youn,
Hyon Bin Na,
Taekyung Yu,
Hwan Kim,
Sang-Mok Lee Dr,
Yoon-Mo Koo Prof,
Ja Hun Kwak Dr,
Hyun Gyu Park Prof,
Ho Nam Chang Prof,
Misun Hwang,
Je-Geun Park Prof,
Jungbae Kim Dr,
Taeghwan Hyeon Prof
Small 01/2008; 4(1):143 - 152. · 8.35 Impact Factor
-
Moon Il Kim,
Jungbae Kim,
Jinwoo Lee,
Hongfei Jia,
Hyon Bin Na, Jong Kyu Youn,
Ja Hun Kwak,
Alice Dohnalkova,
Jay W Grate,
Ping Wang,
Taeghwan Hyeon,
Hyun Gyu Park,
Ho Nam Chang
[show abstract]
[hide abstract]
ABSTRACT: alpha-chymotrypsin (CT) and lipase (LP) were immobilized in hierarchically-ordered mesocellular mesoporous silica (HMMS) in a simple but effective way for the enzyme stabilization, which was achieved by the enzyme adsorption followed by glutaraldehyde (GA) crosslinking. This resulted in the formation of nanometer scale crosslinked enzyme aggregates (CLEAs) entrapped in the mesocellular pores of HMMS (37 nm), which did not leach out of HMMS through narrow mesoporous channels (13 nm). CLEA of alpha-chymotrypsin (CLEA-CT) in HMMS showed a high enzyme loading capacity and significantly increased enzyme stability. No activity decrease of CLEA-CT was observed for 2 weeks under even rigorously shaking condition, while adsorbed CT in HMMS and free CT showed a rapid inactivation due to the enzyme leaching and presumably autolysis, respectively. With the CLEA-CT in HMMS, however, there was no tryptic digestion observed suggesting that the CLEA-CT is not susceptible to autolysis. Moreover, CLEA of lipase (CLEA-LP) in HMMS retained 30% specific activity of free lipase with greatly enhanced stability. This work demonstrates that HMMS can be efficiently employed as host materials for enzyme immobilization leading to highly enhanced stability of the immobilized enzymes with high enzyme loading and activity.
Biotechnology and Bioengineering 03/2007; 96(2):210-8. · 3.95 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We have developed miniature biofuel cells (BFCs) with dimensions as small as 12×12×9 mm by adopting the design of stackable proton exchange membrane (PEM) fuel cells. The enzymatic anodes were constructed by using stabilized glucose oxidase (GOx) in the form of crosslinked enzyme clusters (CECs) on the surface of carbon nanotubes (CNTs). The combination of stabilized GOx and unbuffered fuel solution resulted in stabilized performance of miniature BFCs under continuous operation for more than 16 hours. This unprecedentedly high operational stability of miniature BFCs opens up new possibilities for many BFC applications.
Electroanalysis 09/2006; 18(19‐20):2016 - 2022. · 2.87 Impact Factor
-
Jungbae Kim,
Jinwoo Lee,
Hyon Bin Na,
Byoung Chan Kim, Jong Kyu Youn,
Ja Hun Kwak,
Karam Moon,
Eunwoong Lee,
Jaeyun Kim,
Jongnam Park,
Alice Dohnalkova,
Hyun Gyu Park,
Man Bock Gu,
Ho Nam Chang,
Jay W Grate,
Taeghwan Hyeon
Small 01/2006; 1(12):1203-7. · 8.35 Impact Factor
-
Jungbae Kim Dr,
Jinwoo Lee Dr,
Hyon Bin Na,
Byoung Chan Kim Dr, Jong Kyu Youn,
Ja Hun Kwak Dr,
Karam Moon,
Eunwoong Lee,
Jaeyun Kim,
Jongnam Park Dr,
Alice Dohnalkova,
Hyun Gyu Park Prof,
Man Bock Gu Prof,
Ho Nam Chang Prof,
Jay W. Grate Dr,
Taeghwan Hyeon Prof
Small 10/2005; 1(12):1203 - 1207. · 8.35 Impact Factor
