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11.
Sang-Mok Lee Li Hua Jin Jae Hyun Kim Sung Ok Han Hyon Bin Na Taeghwan Hyeon Yoon-Mo Koo Jungbae Kim Jung-Heon Lee 《Bioprocess and biosystems engineering》2010,33(1):141-147
β-Glucosidase (βG) can relieve the product inhibition of cellobiose in the cellulosic ethanol production by converting cellobiose
into glucose. For the potential recycled uses, βG was immobilized and stabilized in the form of enzyme coating on polymer
nanofibers. The βG coating (EC-βG) was fabricated by crosslinking additional βG molecules onto covalently attached βG molecules
(CA-βG) via glutaraldehyde treatment. The initial activity of EC-βG was 36 times higher than that of CA-βG. After 20 days
of incubation under shaking, CA-βG and EC-βG retained 33 and 91% of each initial activity, respectively. Magnetic nanofibers
were also used for easy recovery and recycled uses of βG coating. It is anticipated that the recycled uses of highly active
and stable βG coating can improve the economics of cellulosic ethanol production so long as economical materials are employed
as a host of enzyme immobilization. 相似文献
12.
Young-Bum Kim Ji-Ho Park Woo-Jin Chang Yoon-Mo Koo Eun-Ki Kim Jin-Hwan Kim 《Biotechnology and Bioprocess Engineering》2006,11(4):288-292
Through statistically designed experiments, lysis agents were optimized to effectively disrupt bacterial cells in a microfluidic
device. Most surfactants caused the efficient lysis of Gram-positive microbes, but not of Gram-negative bacteria. A Plackett-Burman
design was used to select the components that increase the efficiency of the lysis of the Gram-negative bacteriaEscherichia coli. Using this experimental design, both lysozyme and benzalkonium chloride were shown to significantly increase the cell lysis
efficiency, and ATP was extracted in proportion to the lysis efficiency. Benzalkonium chloride affected the cell membrane
physically, while lysozyme destroyed the cell wall, and the amount of ATP extracted increased through the synergistic interaction
of these two components. The two-factor response-surface design method was used to determine the optimum concentrations of
lysozyme and benzalkonium chloride, which were found to be 202 and 99 ppm, respectively. The lysis effect was further verified
by microscopic observations in the microchannels. These results indicate that Gram-negative cells can be lysed efficiently
in a microfluidic device, thereby allowing the rapid detection of bacterial cells using a bioluminescence-based assay of the
released ATP. 相似文献
13.
“Bottom-up” approach for implementing nano/microstructure using biological and chemical interactions
Sang Woo Lee Woo-Jin Chang Rashid Bashir Yoon-Mo Koo 《Biotechnology and Bioprocess Engineering》2007,12(3):185-199
The “Bottom-up” approach for implementing nano/microstructure using biological self-assembled systems has been investigated
with tremendous interest by many researchers in the field of medical diagnostics, material synthesis, and nano/microelectronics.
As a result, the techniques for achieving these systems have been extensively explored in recent years. The developed or developing
techniques are based on many interdisciplinary areas such as biology, chemistry, physics, electrical engineering, mechanical
engineering, and so on. In this paper, we review the fundamentals behind the self-assembly concepts and describe the state
of art in the biological and chemical self-assembled systems for the implementation of nano/microstructures. These structures
described in the paper can be applied to the implementation of hybrid biosensors, biochip, novel bio-mimetic materials, and
nano/microelectronic devices. 相似文献
14.
Summary -Cyclodextrin(-CD) was produced by cyclodextrin glycosyltransferase(CGTase) in aqueous two-phase system. -CD production from soluble starch was catalyzed by CGTase in dextran-rich bottom phase, and the -CD produced was transferred to PEG-rich top phase in aqueous two-phase system, composed of 7% (w/w) polyethylene glycol(Mr 20,000) and 10% (w/w) dextran(Mr 38,900). Partition coefficients of -CD and CGTase were 1.5 and 0.25, respectively. The total productivity of -CD in aqueous two-phase system was about 3 times of that in dextran phase. 相似文献
15.
Sung-Mi Hwang Hye-Jin Kang Sang-Woo Bae Woo-Jin Chang Yoon-Mo Koo 《Biotechnology and Bioprocess Engineering》2010,15(2):213-219
The effects of salt concentration in mobile phase, elution strategy, and hydrophobicity of stationary phase on lysozyme refolding
in hydrophobic interaction chromatography (HIC) were investigated. Butyl Sepharose 4 Fast Flow, the least hydrophobic HIC
resin among the tested adsorbent, showed the best refolding yield. The binding efficiency of unfolded lysozyme on the adsorbent
was maximized when 1 and 0.4 M of initial and final concentration of ammonium sulfate was used in mobile phase, respectively.
The optimum gradient strategy for refolding and elution of lysozyme was determined as linear increase of urea concentration
to 4M. The optimized condition suggests the less hydrophobic environment than conventionally used salt solutions and HIC resins.
Consequently, total refolding yield was improved 1.6 times comparing with optimized dilution-based batch refolding method. 相似文献
16.
Sang Hyun Lee Thanh Thi Ngoc Doan Keehoon Won Sung Ho Ha Yoon-Mo Koo 《Journal of Molecular Catalysis .B, Enzymatic》2010,62(2):169-172
The immobilization of lipases within sol–gel derived silica, using multi-walled carbon nanotubes (MWNTs) as additives in order to protect the inactivation of lipase during sol–gel process and to enhance the stability of lipase, was investigated. Three sol–gel immobilized lipases (Candida rugosa, Candida antarctica type B, Thermomyces lanuginosus) with 0.33% (w/w) MWNT showed much higher activities than lipase immobilized without MWNT. The influence of MWNT content and MWNT shortened by acid treatment in the sol–gel process on the activity and stability of immobilized C. rugosa lipase was also studied. In hydrolysis reaction, immobilized lipase containing 1.1% pristine MWNT showed 7 times higher activity than lipase immobilized without MWNT. The lipase coimmobilized with 2.7% shortened MWNT showed 10 times higher activity in esterification reaction, compared with lipase immobilized without MWNT. The lipase coimmobilized with 2.7% shortened MWNT retained 96% of initial activity after 5 times reuse, while the lipase immobilized without MWNT was fully inactivated under the same condition. 相似文献
17.
Sung Ho Ha Nguyen Minh Hiep Sang Hyun Lee Yoon-Mo Koo 《Bioprocess and biosystems engineering》2010,33(1):63-70
Lipase-catalyzed esterification of glucose with fatty acids in ionic liquids (ILs) mixture was investigated by using supersaturated
glucose solution. The effect of ILs mixture ratio, substrate ratio, lipase content, and temperature on the activity and stability
of lipase was also studied. The highest yield of sugar ester was obtained in a mixture of 1-butyl-3-methylimidazolium trifluoromethanesulfonate
([Bmim][TfO]) and 1-methyl-3-octylimidazolium bis[(trifluoromethyl)-sulfonyl]amide ([Omim][Tf2N]) with a volume ratio of 9:1, while Novozym 435 (Candida antarctica type B lipase immobilized on acrylic resin) showed the optimal stability and activity in a mixture of [Bmim][TfO] and [Omim][Tf2N] with a 1:1 volume ratio. Reuse of lipase and ILs was successfully carried out at the optimized reaction conditions. After
5 times reuse of Novozym 435 and ILs, 78% of initial activity was remained. 相似文献
18.
Suk-Chan Park Woo-Jin Chang Sang-Mok Lee Young-Jun Kim Yoon-Mo Koo 《Biotechnology and Bioprocess Engineering》2005,10(1):99-102
Organic solvents are widely used in biotransformation systems. There are many efforts to reduce the consumption of organic
solvents because of their toxicity to the environment and human health. In recent years, several groups have started to explore
novel organic solvents called room temperature ionic liquids in order to substitute conventional organic solvents. In this
work, lipase-catalyzed transesterification in several uni-and bi-phasic systems was studied. Two representative hydrophobic
ionic liquids based on 1-butyl-3-methylimidazolum coupled with hexafluorophosphate ([BMIM][PF6]) and bis[(trifluoromethylsulfonyl) imide] ([BMIM] [Tf2N]) were employed as reaction media for the transesterification ofn-butanol. The commercial lipase, Novozym 435, was used for the transesterification reaction with vinyl acetate as an acyl
donor, The conversion yield was increased around 10% in a water/[BMIM][Tf2N], bi-phasic system compared with that in a water/hexane system. A higher distribution of substrates into the water phase
is believed to enhance the conversion yield in a water/[BMIM][Tf2N] system. Partion coefficients of the substrates in the water/[BMIM][Tf2N] bi-phasic system were higher than three times that found in the water/hexane system, while n-butyl acetate showed a similar
distribution in both systems. Thus, RTILs appear to be a promising substitute of organic solvents in some biotransformation
systems. 相似文献
19.
Kumar C. Ganesh Joo Han-Seung Koo Yoon-Mo Paik Seung R. Chang Chung-Soon 《World journal of microbiology & biotechnology》2004,20(4):351-357
An oxidative and SDS-stable alkaline protease secreted by a marine haloalkalophilic Bacillus clausii isolated from the tidal mud flats of the Korean Yellow Sea near Inchon City was investigated in batch fermentation in shake
flasks and in a bioreactor under a range of conditions. The isolate produced maximum protease yields (15,000 U ml−1) under submerged fermentation conditions at 42 °C for 40 h with an aeration of 1.5 v/v/min and agitation of 400 rev/min in
a formulated soybean—casein medium (pH 9.6) containing (w/v): soybean meal (2%), casein (1%), corn starch (0.5%), NH4Cl (0.05%), NaCl (0.05%), KH2PO4(0.04%), K2HPO4(0.03%), MgSO4(0.02%), yeast extract (0.01%) and Na2CO3(0.6%). The optimal pH and temperature of activity of the partially purified enzyme were 11.5 and 80 °C, respectively. The
alkaline protease showed extreme stability towards SDS and oxidizing agents, retaining its activity above 96 and 75% on treatment
for 72 h with 5% SDS and 5% H2O2, respectively. The inhibition profile exhibited by phenylmethanesulphonyl fluoride suggested that the protease from B. clausii belongs to the family of serine proteases. 相似文献
20.
Novozym 435-catalyzed synthesis of 6-O-lauroyl-d-glucose in ionic liquids (ILs) was investigated. The highest lipase activity was obtained in water-miscible [Bmim][TfO] which can dissolve high concentration of glucose, while the highest stability of lipase was shown in hydrophobic [Bmim][Tf(2)N]. The optimal activity and stability of lipase could be obtained in [Bmim][TfO] and [Bmim][Tf(2)N] mixture (1:1, v/v). Specifically, the activity of lipase was increased from 1.1 to 2.9 micromolmin(-1)g(-1) by using supersaturated glucose solution in this mixture, compared with reaction using saturated solution. After 5 times reuse of lipase, 86% of initial activity was remained in this mixture, while the residual activity in pure [Bmim][TfO] was 36%. Therefore, the productivity obtained by using ILs mixtures was higher than those in pure ILs. 相似文献