• Journal of Microbiology and Biotechnology
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• v.18 no.7
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• pp.1257-1265
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• 2008

To lower the cost of ethanol distillation of fermentation broths, a high initial glucose concentration is desired. However, an increase in the substrate concentration typically reduces the ethanol yield because of insufficient mass and heat transfer. In addition, different operating temperatures are required to optimize the enzymatic hydrolysis (50$^{\circ}C$) and fermentation (30$^{\circ}C$). Thus, to overcome these incompatible temperatures, saccharification followed by fermentation (SFF) was employed with relatively high solid concentrations (10% to 20%) using a portion loading method. In this study, glucose and ethanol were produced from Solka Floc, which was first digested by enzymes at 50$^{\circ}C$ for 48 h, followed by fermentation. In this process, commercial enzymes were used in combination with a recombinant strain of Zymomonas mobilis (39679:pZB4L). The effects of the substrate concentration (10% to 20%, w/v) and reactor configuration were also investigated. In the first step, the enzyme reaction was achieved using 20 FPU/g cellulose at 50$^{\circ}C$ for 96 h. The fermentation was then performed at 30$^{\circ}C$ for 96 h. The enzymatic digestibility was 50.7%, 38.4%, and 29.4% after 96 h with a baffled Rushton impeller and initial solid concentration of 10%, 15%, and 20% (w/v), respectively, which was significantly higher than that obtained with a baffled marine impeller. The highest ethanol yield of 83.6%, 73.4%, and 21.8%, based on the theoretical amount of glucose, was obtained with a substrate concentration of 10%, 15%, and 20%, respectively, which also corresponded to 80.5%, 68.6%, and 19.1%, based on the theoretical amount of the cell biomass and soluble glucose present after 48 h of SFF.

• Journal of the Korean Applied Science and Technology
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• v.35 no.4
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• pp.1048-1056
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• 2018

Non-edible oil sources (i.e., Palm Acid Oil, waste animal fat) usually contain relatively high amount of free fatty acids (FFA) that make them inadequate for direct base catalyzed transesterification reaction. Enzymatic biodiesel synthesis can solve several problems posed by the alkaline-catalyzed transesterification, and has certain advantages over the chemical catalysis of transesterification, as it is less energy intensive, allows easy recovery of glycerol and the transesterification of glycerides with high free fatty acid contents. In this study, we synthesized biodiesel through enzymatic catalyzed process using high free fatty acid containing waste oil in biodiesel reactor (1 ton/day) and optimized the biodiesel production processes.

• Food Science and Biotechnology
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• v.17 no.1
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• pp.118-122
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• 2008

The use of tartary buckwheat flour as a source of dietary rutin has been limited because of the enzymatic degradation of rutin during the dough-making process, which results in a bitter taste. A variety of pretreatment regimes, including heating, steaming, boiling, and extruding, were evaluated in relation to the inactivation of the rutin-degrading enzyme responsible for rutin loss and color change during dough-making. Steaming (120 see), boiling (90 see) buckwheat grains, or extruding (180 rpm/min at $140^{\circ}C$) the flour resulted in the retention of >85% of the original rutin and eliminated the bitter taste in the hydrated flours. In contrast, dry heating at $140^{\circ}C$ for 9 min or microwaving at 2,450 MHz for 3 min did not reduce the rutin loss, and the bitter taste remained. Unlike in the flour, the rutin degradation in water-soaked grains was insignificant at room temperature. Moreover, the samples treated by steaming, boiling, or extrusion were darker and more reddish in color.

• KSBB Journal
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• v.26 no.3
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• pp.243-247
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• 2011

Using Bacillus subtilis spore display system, with cotG as an anchoring motif, levansucrase from Zymomonas mobilis, was displayed on the outer surface of Bacillus subtilis spore. Flow cytometry of DB104 (pSDJH-cotG-levU) spore, proved the surface localization of CotG-LevU fusion protein on the spore compared to that of DB104. Enzymatic activity of DB104 (pSDJH-cotG-levU) spore showed more than 1.5 times higher levansucrase specific activity compared to that of the host spore, which is a remarkable increase of enzymatic activity considering the existence of sacA (sucrase) and sacB (levansucrase) in the Bacillus subtilis chromosome. The spore integrity, revealed by sporulation frequency test after heat and lysozyme treatment of spore, did not changed at all in spite of the CotG-LevU fusion protein incorporation into the spore coat layer during spore formation process. These data prove again that Bacillus subtilis spore could be considered as good live immobilization vehicle for efficient bioconversion process.

• Journal of Microbiology and Biotechnology
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• v.25 no.12
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• pp.2034-2042
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• 2015

A one-pot process of enzymatic synthesis of deoxythymidine-5'-triphosphate (5'-dTTP) employing whole cells of recombinant Escherichia coli coexpressing thymidylate kinase (TMKase) and acetate kinase (ACKase) was developed. Genes tmk and ack from E. coli were cloned and inserted into pET28a(+), and then transduced into E. coli BL21 (DE3) to form recombinant strain pTA in which TMKase and ACKase were simultaneously overexpressed. It was found that the relative residual specific activities of TMKase and ACKase, in pTA pretreated with 20 mM ethylene diamine tetraacetic acid (EDTA) at 25℃ for 30 min, were 94% and 96%, respectively. The yield of 5'-dTTP reached above 94% from 5 mM deoxythymidine 5'-monophosphate (5'-dTMP) and 15 mM acetyl phosphate catalyzed with intact cells of pTA pretreated with EDTA. The process was so effective that only 0.125 mM adenosine-5'-triphosphate was sufficient to deliver the phosphate group from acetyl phosphate to dTMP and dTDP.

• KSBB Journal
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• v.10 no.2
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• pp.159-165
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• 1995

Methyl fructoside was continuously produced in suspended bed enzyme reactor using alginate-enclosed microspheres biocatalyst which was developed for enzymatic synthesis of methyl fructoside. And the continuous operating conditions were optimized with reactor simulation in order to demonstrate a feasibility of commercialization of the continuous enzymatic production process development. The yield and productivity of methyl fructoside were as high as 47.1%o and $2g/\ell$-hr, respectively. The optimum operating conditions were pH 4.8, 30%(v/v) of methanol content and $2U/m\ell$ of enzyme activity when the initial concentration of sucrose is $0.291mo1/\ell$ at the reaction temperature of $25^{\circ}C$.

• KSBB Journal
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• v.28 no.6
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• pp.366-371
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• 2013

Ethanol productions were performed by separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) processes using seaweed, Enteromorpha intestinalis (sea lettuce). Pretreatment conditions were optimized by the performing thermal acid hydrolysis and enzymatic hydrolysis for the increase of ethanol yield. The pretreatment by thermal acid hydrolysis was carried out with different sulfuric acid concentrations in the range of 25 mM to 75 mM $H_2SO_4$, pretreatment time from 30 to 90 minutes and solid contents of seaweed powder in the range of 10~16% (w/v). Optimal pretreatment conditions were determined as 75 mM $H_2SO_4$ and 13% (w/v) slurry at $121^{\circ}C$ for 60 min. For the further saccharification, enzymatic hydrolysis was performed by the addition of commercial enzymes, Celluclast 1.5 L and Viscozyme L, after the neutralization. A maximum reducing sugar concentration of 40.4 g/L was obtained with 73% of theoretical yield from total carbohydrate. The ethanol concentration of 8.6 g/L of SHF process and 7.6 g/L of SSF process were obtained by the yeast, Saccharomyces cerevisiae KCTC 1126, with the inoculation cell density of 0.2 g dcw/L.

• Journal of the Korean Society of Clothing and Textiles
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• v.30 no.8
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• pp.1323-1332
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• 2006

Lyocell is a regenerated cellulose fiber manufactured by an environmentally-friendly process. Since the fiber has more crystalline region compared to rayon, lyocell shows higher wet-strength than rayon. Although fibril generation of lyocell is lower than that of rayon because of the reason, the fibril generated during the wet process deteriorates the smooth look and soft touch of the fabric. The efficient way to remove the fibril yet retain the strength property was investigated in this work. In order to scour and remove the fibril from the fabric, cellulase enzymes were introduced and the traditional scouring was carried to be compared. Weight loss, dye-ability, and strength of treated fabric were measured after the treatments. Scanning electron microscopy was used to observe the surface of the fiber. Among the cellulases used in this work, Denimax 992L showed the best results for removal of fibril with low weight loss and tensile strength loss. The optimal conditions for the enzymatic treatment could be chosen depending on a characteristic for final purpose of the lyocell product.

• Journal of the Korean Society of Clothing and Textiles
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• v.37 no.8
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• pp.1107-1116
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• 2013

This study examined the use of cutinase and lipase to process cotton/polyester blend fabric. Optimum treatment conditions for cutinase and lipase were investigated for cotton/polyester blend fabric. The properties of enzyme-treated fabrics were evaluated and compared in optimal treatment conditions. In addition, the possibility to provide an enzymatic finishing on blend fabrics using mixed enzymes in a two-step process were studied. The weight loss of cotton/polyester blend fabrics with Triton X-100 was 0.8% and the dyeing property of blend fabrics with calcium chloride increased by a factor of 1.2. The use of two enzymes in combination with cutinase and lipase in the presence of auxiliaries resulted in a cotton/polyester blend fabric weight loss of 0.8%. In addition, the dyeing properties of cotton/polyester blend fabrics improved by a factor of 1.5 and the moisture regain of cotton/polyester blend fabrics improved by a factor of 1.16. However, no marked loss was observed in tensile strength. The surface morphology of cotton/polyester blend fabrics is modified through a two-enzyme treatment. The treatment of cotton/polyester blend fabrics with cutinase and lipase maintains cotton strength and improves the moisture regain of polyester fabrics.

• Microbiology and Biotechnology Letters
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• v.11 no.3
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• pp.193-199
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• 1983

Systematic bioconversion process for the production of xylose from agricultural wastes such as barley straw and corn cobs was studied. After the pretreatment in 1 % NaOH solution for 24 hours at 3$0^{\circ}C$, enzymatic hydrolysis of barley straw for 48 hours at 3$0^{\circ}C$ resulted in the liberation of 15.8% of reducing sugar which is equivalent to 87% of total D-xylose content. Among various agricultural wastes, corn cob as well as barley straw was demonstrated to be potent sources for the production of D-xylose by the process of enzymatic conversion.