• Journal of Microbiology and Biotechnology
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• 제11권6호
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• pp.1002-1010
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• 2001

The D-xylose operon in Escherichia coli is known to be regulated by a transcriptional activator protein, XyIR, which is responsible for the expression of both xylAB and xylFGH gene clusters. The XyIR was purified to homogeneity by using the maltose binding protein fusion expression and purification systems involving two chromatography steps. The purified XyIR protein was composed of two subunits of 45 kDa, which was determined by both sodium dodecyl sulfate polyacrylamide gel electrophoresis and gel filtration. The purified XyIR was specifically bounded to the xylA promoter, regardless of adding xylose to the reaction mixture, but binding of XylR was specifically bounded to the xylA promoter, regardless of adding xylose to the reaction mixture, but binding of XylR to the xylA promoter was enhanced by adding xylose. The enhanced binding ability of XyIR in the presence of xylose was not diminished by adding glucose. The presumed XyIR binding site is located between 120 bp to 100 bp upstream the xylA initiation codon.

• 한국식품영양학회지
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• 제25권4호
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• pp.787-792
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• 2012

본 연구의 목적은 설탕의 Glycemic index(GI) 저감효과를 기대할 수 있는 D-xylose의 적정 농도를 조사하는 것이다. 그 결과, 5% D-xylose 첨가 설탕의 GI는 일반설탕의 GI 수치인 68에 비해 약 27.5% 낮은 49.3이었으며, 10% D-xylose 첨가 설탕의 GI는 약 25.9% 낮은 50.4로 확인되었다. D-xylose 첨가 설탕의 GI는 D-xylose의 농도 증가에 따라 의존적으로 감소하지는 않는 것으로 확인되었으며, 5% D-xylose 첨가 설탕(XyloSugar)의 GI 저감효과가 10% D-xylose 첨가 설탕(XyloSugar10)의 GI 저감효과와 차이가 없음을 확인하였다. D-xylose는 설탕에 비해 고가일 뿐만 아니라 감미도도 설탕보다 낮다. 그러므로 D-xylose의 농도가 낮을수록 가격, 맛에 있어서 장점이 있다. 따라서 설탕의 GI 저감효과를 기대할 수 있는 D-xylose의 적정 농도는 5%(w/w)로 판단된다.

• 생명과학회지
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• 제21권3호
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• pp.335-340
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• 2011

포도당과 자일로스는 자연계에서 가장 풍부한 물질이며 이들은 효모에 의해 에탄올로 전환될 수 있다. 본 연구에서는 Saccharomyces cerevisiae와 Pichia stipitis을 이용하여 분리배양, 공동배양 그리고 순차배양 등의 조합을 통해 가장 효과적인 발효의 방법을 찾고자 하였다. 분리배양에서 S. cerevisiae은 29.4 g/l의 포도당을 발효하여 14.5 g/l의 에탄올을 생산한 반면에 자일로스를 이용하지 못했다. 그렇지만 P. stipitis은 포도당뿐만 아니라 자일로스도 분해하여 각각 포도당 29.4 g/l로부터 11.9 g/l의 에탄올을, 자일로스 29.0 g/l로부터 11.6 g/l의 에탄올을 생산하였다. 포도당과 자일로스 혼합배양에서, S. cerevisiae은 13.4 g/l의 에탄올을 생산한 반면에 P. stipitis은 21.1 g/l의 에탄올을 생산하였다. 공동배양과 순차배양에서, 공동배양이 18.6 g/l, 순차배양이 12.4 g/l의 에탄올을 생산하여 공동배양이 더 효과적인 것으로 나타났다. 두 효모의 생장에서 영양분의 효과를 보기 위해 yeast nitrogen base (YNB)을 S. cerevisiae가 포도당을 소모한 시점에 첨가하니 자일로스의 소비량과 미생물의 성장이 증가하였고 54.6 g/l의 당 혼합배양액에서 22.5 g/l의 에탄올을 생산하여 0.41 g/g의 수득율을 나타내었다.

• 한국식품조리과학회지
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• 제15권4호
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• pp.363-369
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• 1999

The study was carried out to compare the reaction rate of caramel type browning reaction of xylose(XY), glocose(GL), sucrose(SU), glucose+citric acid(GLCA), glucose+sodiumcitrats(GLSC), glucose+glycine(GLGC) heated at 60, 80, 100, 120 and 140$^{\circ}C$ for 24 hours, respectively. 1. The color intensity (absorbance at 490 nm) of the browning reaction mixtures tends to increase as the browning reaction time gets longer and the browning of reaction temperature gets higher. But the degree of the intensity of SU and GLCA changes very little. 2. The reaction rate constant (K) was increased rapidly above 120$^{\circ}C$ and appeared maximum at 140$^{\circ}C$, especially GLGC (140.25) was the highest. The activation energy (Ea) of sugars. XY had the highest value (124.36 J/mol), while SU the lowest(104.68 J/mol). Mixtures of GLGC was shown to have higher activation energy (144.94 J/mol) than the sugar alone and Q$\_$10/ values of GLGC were 1.68-2.85. 3. The residual amount of reactants such as xylose, glucose, sucrose, citric acid, sodium citrate and glycine in each browning mixture were decreased upon the browning reaction temperature increasing. In the GLCA, GLSC and GLGC browning mixtures, respectively, the residual amounts of glucose were less than those with amino acid, organic acid and their salt.

• Journal of the Korean Wood Science and Technology
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• 제31권6호
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• pp.60-66
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• 2003

Mycelial growth of L. edodes by supplement nutrition of softwood was studied on a sawdust medium. The sawdust used was from the following softwood species : Larix leptolepis, Pinus densiflora and Pinus koraiensis. The added nutritions consisted of carbon nutritions(sucrose, active carbon, xylose, glucose, paper pellet), nitrogen nutritions(potassium nitrate, ammonium chloride, asparagine, glutamic acid) and vegetable oil(rice bran oil). The sawdust medium was a mixture of 76% sawdust, 20% rice bran, 3% carbon nutrition, 0.4% nitrogen nutrition and 0.6% calcium carbonate. Following addition of carbon and nitrogen nutritions on the sawdust medium proved most suitable : L. leptolepis (glucose, glutamic acid), P. densiflora (active carbon, asparagine) and P. koraiensis (xylose, glutamic acid). The highest mycelial growth was obtained from sawdust medium of optimum condition with 97% of L. leptolepis, 110% of P. densiflora and 98% of P. koraiensis. This study has provided useful preliminary information for the cultivation of L. edodes.

• 생명과학회지
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• 제27권12호
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• pp.1403-1409
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• 2017

본 연구에서는 lignocellulosic biomass (xylose)의 부가가치를 높이고 효율적인 활용을 위해 xylitol dehydrogenase를 Saccharomyces cerevisiae 숙주세포에서 분비 생산하고자 하였다. 먼저 S. cerevisiae와 Pichia stipitis유래 XYL2 유전자(S.XYL2 and P.XYL2 gene)의 발현 시스템을 구축하기 위하여 GAL10 promoter와 ADH1 promoter 하류에 각각 mating factor ${\alpha}$ ($MF{\alpha}$) signal sequence와 XYL2유전자를 가진 $pGMF{\alpha}-S.XYL2$, $pGMF{\alpha}-P.XYL2$, $pAMF{\alpha}-S.XYL2$와 $pAMF{\alpha}-P.XYL2$ plasmid를 구축하였다. 각각의 plasmid는 S. cerevisiae $SEY2102{\Delta}trp1$ 균주에 형질전환되었고, 생산된 xylitol dehydrogenase의 활성을 조사해 본 결과, GAL10 promoter가 ADH1 promoter보다 XYL2유전자의 발현에 더욱 적합함을 확인 할 수 있었다. 또한 P. stipitis 유래의 xylitol dehydrogenase 효소 활성이 S. cerevisiae 유래의 효소 활성보다 2배 이상 더 높았으며, 활성의 증가를 위해 두 유전자 모두 cofactor로 $NAD^+$에 의존한다는 것을 확인하였다. 재조합 유전자가 가지는 분비서열에 의해 $SEY2102{\Delta}trp1/pGMF{\alpha}-P.XYL2$ 균주에서 xylitol dehydrogenase의 약 77%는 periplasmic space로 분비 발현되었음을 알 수 있었다. 또한 재조합 xylitol dehydrogenase의 효율적인 생산을 위해 탄소원의 영향을 조사해본 결과, glucose 단독보다 glucose와 xylose를 혼합 배양한 경우에서 효소활성이 최대 41% 정도 증가되었음을 확인 할 수 있었다. 본 연구에서 최적화한 발현 시스템 및 배양 조건은 xylose 뿐만 아니라 다양한 biomass를 이용한 유용물질 생산을 위한 관련 단백질의 발현 분비시스템 구축 및 대량생산에도 응용될 수 있을 것이라 생각된다.

• Preventive Nutrition and Food Science
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• 제13권3호
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• pp.249-252
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• 2008

Flow behaviors of sweet potato starch (SPS) pastes (5% w/w) were studied in the presence of various sugars (xylose, glucose, fructose and sucrose) and sugar alcohols (xylitol and sorbitol). The flow properties of SPS-sugar mixtures were determined from the rheological parameters of power law model. The vane method was also employed for determining yield stresses of SPS-sugar mixtures directly under a controlled low shear rate. At $25^{\circ}C$ all the samples showed shear-thinning behaviors ($n=0.35{\sim}0.44$) with yield stress. The consistency index (K) values of SPS-sugar mixtures increased in the following order: sorbitol> xylitol> control (no sugar)> sucrose> fructose> glucose> xylose, showing that the addition of sugar alcohols enhanced the K values. The yield stress values were reduced in the presence of ugars and sugar alcohols and they also increased with an increase in swelling power of starch granules in the SPS-sugar mixture systems.

• 한국산학기술학회논문지
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• 제11권7호
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• pp.2522-2527
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• 2010

본 연구의 목적은 초음파 처리 키토산과 메일라드 반응액 혼합물에 의한 tyrosinase 억제 활성과 항균력을 조사하고자 하였다. 감자로부터 tyrosinase를 분리하여 SDS-PAGE후 일반 단백질 염색과 tyrosinase 활성 염색을 행하여 tyrosinase를 확인하였다. 여러 가지 당 (glucose, fructose, galactose, xylose, arabinose or ribose)과 cystein과의 반응으로 생성된 메일라드 반응 산물의 tyrosinase 억제 활성을 비교한 결과, glucose과 cystein 반응으로 생성된 메일라드 반응 산물의 tyrosinase 억제 활성이 가장 높은 것으로 나타났다. 0.5% 아세트산에 녹인 1% 키토산을 시간별로 초음파 처리한 후 항균력을 조사한 결과 1 시간 이상 초음파 처리한 경우 E. coli 균주 와 S. aureus 균주에서 억제 활성을 보였다. 갈변 억제 활성과 항균력을 가진 혼합물 제조를 위하여 초음파 처리 키토산과 메일라드 반응액을 혼합비를 달리하여 조사한 결과 부피 비로 1 : 1 로 혼합한 경우가 tyrosinase 억제 활성과 항균력이 가장 효과가 높은 것으로 조사되었다.

• Journal of Microbiology and Biotechnology
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• 제2권2호
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• pp.78-84
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• 1992

Streptomyces sp. No.8, which produced glucose isomerase was isolated from soil samples. The isolated strain, No.8, was identified as belonging to the Genus Streptomyces. A mutant strain, SM 805, showed the greatest ability to produce glucose isomerase. It was developed from the strain, No.8, by mutagenesis induced by NTG and UV treatment. The mutant strain, SM 805, produced about 7 times more glucose isomerase than the parental strain, No.8. This enzyme catalyzed the isomerization of D-xylose, D-glucose and D-ribose. It was inactive in the absence of metal ions, but was activated by the addition of $Mg^{2+}$ or $Co^{2+}$. The optimum temperature and pH for enzyme activity were $80^\circ{C}$ and pH 8.5, respectively. The enzyme was stable in a pH range of 6.0 to 10.0, and it was highly thermostable. There was no activity loss below $80^\circ{C}$, and even above $90^\circ{C}$ about 45% of its activity was retained. The reaction equilibrium was reached when about 53% fructose was present in the reaction mixture. Whole cells containing glucose isomerase from Streptomyces sp. SM 805 were immobilized by glutaraldehyde treatment. The resultant immobilized enzyme pellets showed a relatively long stability during the isomerizing reaction. The half-life of the immobilized enzyme during the operating was 45 days in the presence of 10mM $Mg^{2+}$.

• 신재생에너지
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• 제9권1호
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• pp.25-32
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• 2013

It is indispensable to increase the conversion rate of a reducing sugars such as pentose and hexose derived from cellulosic wastes for a highly efficient bioethanol fermentation from food wastes. The saccharification liquid from cellulosic substrates such as vegetable food wastes contained lots of hexose like glucose and pentose like xylose. Since Saccharomyces-based yeasts could not convert xylose to bioethanol, Pichia stipitis which could directly ferment xylose to ethanol was chosen. After selecting Saccharomyces coreanus and P. stipitis, fermentation characteristics by mixture of two yeasts were investigated. As a result, it was verified the production of ethanol was enhanced by the co-fermentation, although there were somewhat differences between the fermentation characteristics by the aeration methods. Moreover, the consumption of pentose, hexose and disaccharide was obviously observed, and aeration in the process of fermentation seemed to stimulate the activity of P. stipitis.