• Biotechnology and Bioprocess Engineering:BBE
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• 제5권1호
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• pp.32-39
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• 2000

Simultaneous isomerisation and fermentation (SIF) of xylose and simultaneous isomerisation and cofermentation (SICF) of glucose-xylose mixture was carried out by the yeast Saccharomyces cerevisiae in the presence of a compatible xylose isomerase. The enzyme converted xylose to xylulose and S. cerevisiae fermented xylulose, along with glucose, to ethanol at pH 5.0 and $30^{\circ}C$. This compatible xylose isomerase from Candida boidinii, having an optimum pH and temperature range of 4.5-5.0 and $30-35^{\circ}C$ respectively, was partially purified and immobilized on an inexpensive, inert and easily available support, hen egg shell. An immobilized xylose isomerase loading of 4.5 IU/(g initial xylose) was optimum for SIF of xylose as well as SICF of glucose-xylose mixture to ethanol by S. cerevisiae. The SICF of 30 g/L glucose and 70 g xylose/L gave an ethanol concentration of 22.3 g/L with yield of 0.36 g/(g sugar consumed) and xylose conversion efficiency of $42.8\%$.

• 한국미생물·생명공학회지
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• 제16권6호
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• pp.505-509
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• 1988

Xylose 발효효모를 토양에서 분리하였으며 (X-6-41) 이는 Lodder씨 분류기준에 따라 Candida 속으로 동정되었다. 삼각플라스크 정치배양법에 의한 xylose 발효시 2% xylose, N원 asparagine, pH 4에서 발효율 약 80%로 나타났고 Mini-Jar for mentor를 이용하여 glucose와 xylose를 1 : 1로 혼합한 총당 5% 기질에서 발효를 시켜 본 바 발효율은 총당에 대해 약 72.3%(alcohol 2.3%(v/v)였다. 본 균주에 의한 xylose 발효는 일반적으로 보고된 바와 같이 호기적 발효과정이였으며 glucose와 xylose 혼합기질의 경우 glucose가 먼저 이용되고 xylose가 나중에 이용되는 것으로 나타났다. 5% xylose를 기질로 하여 Mini-Jar fermentor에서 발효시켰을 때 최대 발효율 69%(alcohol 2.2%(v/v)로 나타났으며 발효중에 xylitol이 생성되었다.

• 한국식품과학회지
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• 제28권6호
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• pp.1151-1156
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• 1996

Candida parapsilosis KFCC-10875를 사용하여 xylose와 glucose가 xylitol 생산에 미치는 영향을 조사하였다. Xylose만 50 g/l 함유하는 배지에서 배양하면 xylitol만 생성되었고 xylose에 glucose를 첨가하여 배양하면 부산물로 ethanol과 glycerol이 생성되었다. Glucose 함량이 높을수록 xylitol 생성량은 감소하였지만 ethanol과 glycerol의 양은 증가하여 xylose 10 g/l와 glucose 40/l일 때 최대값 각각 21.5 /l, 3.6 g/l의 최대값을 나타내었다. Glucose에서는 xylitol이 생성되지 못하기 때문에 glucose만 존재하는 배지에서는 xylitol이 전혀 생성되지 않았다. Xylose에 대한 glucose의 비율을 증가시키며 배양한 결과 glucose 비율이 높을수록 이용된 xylose에 대한 생성된 xylitol의 수율이 감소하였다. 첨가하는 ethanol의 농도를 변화시키면서 배양한 결과 첨가된 ethanol의 농도가 증가할수록 xylose에 대한 생성된 xylitol의 생산이 감소하였고 부산물을 제거한 후 배양할 경우 xylitol생산이 저해되지 않았다. 이것은 xylose에 대한 생성된 xylitol의 수율이 ethanol가 같은 부산물에 의한 것이라는 것을 의미한다. Xylose 또는 glucose에서 성장한 균체를 약 20 g/l로 농축하여 xylose 50g/l가 포함된 발효배지에 접종하여 배양하였다. Glucose에서 성장한 균체를 사용한 xylitol 생산에서 xylose reductase와 xylitol dehydrogenase의 총역가는 농축균체를 사용하지 않는 일반 배양의 그것과 거의 비슷하였다. 그러나, xylose에서 성장한 농축균체를 사용한 발효에서의 xylose reductase의 역가와 xylitol dehydrogenase의 역가는 비교적 높게 나타나 일반배양의 역가와 비슷하였다. 그러므로 xylitol 생산성은 균체농도를 증가시킬수록 비례적으로 증가하여 xylose에서 성장한 농축균체로 발효시간 18시간에 50 g/l의 xylose로부터 40 g/l의 xylitol을 얻을 수 있었다.

• 한국미생물·생명공학회지
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• 제25권5호
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• pp.495-500
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• 1997

Xylitol production from xylose and glucose was investigated using Candida tropicalis KFCC-10960. As glucose concentration in xylose medium was increased, ethanol production increased. However, xylitol production was maximum at glucose concentration of 10 g/l. The concentrated cells grown on xylose or glucose were inoculated in xylose medium. The specific activities of xylose reductase and xylitol dehydrogenase, and xylitol production in concentrated cells grown on glucose were the same as those in concentrated cells grown on xylose. The results suggested that cells grown on glucose had the same xylitol producing activity as those grown on xylose. By feeding glucose in xylose medium, cell growth was achieved from glucose and xylitol production was obtained from xylose. By using this technique, a final xylitol concentration of 261 g/l was achieved from 300 g/l xylose in 41 hours which corresponded to a xylitol yield from xylose of 87% and a xylitol productivity of 6.37 g/1-h.

• 한국미생물·생명공학회지
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• 제24권2호
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• pp.149-154
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• 1996

Effect of glucose addition to xylose medium on xylitol production was investigated by using Candida parapsilosis ATCC 21019 mutant. With increasing the ratio of glucose to xylose in total amount of 50 g/l as glucose and/or xylose, xylitol production was decreased but ethanol and glycerol production were increased. Ethanol and glycerol concentration were maxmum in 10 g/l of xylose and 40 g/l of glucose medium as 21.5 g/l and 3.6 g/l, respecti- vely. No xylitol was formed in glucose medium without xylose because xylitol could be not produced from glucose. With increasing the ratio of glucose to xylose, the activity of xylose reductase which converted xylose to xylitol were decreased. The activities of xylitol dehydrogeiiase which converted xylitol to xylulose and then cell materials were found to be constant regardless of the ratio of glucose to xylose. This results indicated that glucose addition to xylose medium on cell growth was not affected. In order to prevent the inhibitory effect of glucose on xylitol production, glucose in a fermentor was fed with low concentration and then ethanol and glycerol was critically decreased and the xylitol yield from xylose of the culture with glucose feeding was recovered the almost same as that with only 50 g/l of xylose. However, the xylitol yield from total sugars (xylose and glucose) was decreased and glucose was not contributed to xylitol production. Therefore, the fermentation at high concentration of xylose without glucose was carried out. A final xylitol concentration of 242 g/l which corresponding 80.7% of xylitol yield was obtained from 300 g/l of xylose for 273 hours.

• Asian-Australasian Journal of Animal Sciences
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• 제17권8호
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• pp.1123-1130
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• 2004

Two experiments were conducted to examine the effects of dietary inclusion of xylose on growth performance, nutrient digestibility and xylose absorption in the portal-drained viscera of broiler chicks. In Exp. 1, ninety male 14 day-old broilers were used to study the effects of different inclusion levels (0, 5, 10, 20 and 40%) of D-xylose in the semi-purified diets on the growth and nutrient digestibility of broilers. In Exp. 2, One hundred and eight male broilers, fed by precision feeding at 22 day-old, were used to investigate the absorption and transportation of dietary xylose in the portal-drained viscera of broiler. The results of Exp. 1 indicated that the growth of broilers was gradually decreased as the xylose level increased (p<0.01). With the xylose supplementation increased, the moisture in broiler excreta was gradually elevated (p<0.01), AME and the digestibilities of crude protein and ether extract were significantly reduced and the digestibilities of xylose and arabinose were also decreased (p<0.01). The results of Exp. 2 showed that the concentrations of ribose, xylose and galactose in serum were significantly influenced by different dietary levels of xylose (p<0.01), but there's no apparent difference among rhamnose, glucose and arabinose (p>0.05). The xylose concentration in serum was highest in Vena Cava, middle in Portal Vein and lowest in Ulnar Vein within 6 h after precision feeding. And then the xylose concentration in Portal Vein and Ulnar Vein were higher than that of Vena Cava. The concentration of ribose, xylose and galactose in serum were also significantly changed with time prolongation (p<0.01). The concentration of xylose in serum was highest in the 40% xylose treatment, middle in the 20% xylose group and lowest in the control group. The glycogen contents in liver and muscle were linearly decreased as the level of xylose increased (p<0.01). The higher the dietary level of xylose was, the lower digestibility of dietary xylose was (p<0.10). 40% xylose markedly decreased the digestibility of dietary glucose (p<0.01). In conclusion, high levels of xylose in the diets inhibited the growth and nutrient digestibility of broiler. The outputs of xylose from the hydrolyzation of wheat-based diet by xylanase should have no adverse effects on broiler performance.

• 한국미생물·생명공학회지
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• 제20권1호
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• pp.91-95
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• 1992

Xylose와 cellobiose를 모두 발효할 수 있는 효모를 선발한 결과 Pichia stipitis CBS 5775와 5776이 가장 우수하였다. P.stipitis CBS 5776은 glucose, xylose 및 cellobiose에서 각각 0.4, 0.36 및 0.23g/g substrate의 에탄올 수율을 나타내었다. 혼합당에서의 발효 결과 glucose는 xylose와 cellobiose 이용에 대하여 catabolite regulation을 일으켜서 glucose가 다 소비된 후에 다른 기질이 소비되었다. 그러나 xylose와 cellobiose는 동시에 소비되었다. 혼합기질에서의 에탄올 수율은 단일기질에서의 각각의 수율의 합과 거의 유사하였다.

• 한국식품조리과학회지
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• 제12권1호
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• pp.108-114
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• 1996

The study was carried out to compare the reaction rate of Maillard browning reaction of 2 dipeptides (Leucylglycine, Tryptophylglycine) and 4 amino acids (Lysine, Glycine, Leucine, Tryptophan) with xylose heated for 0∼24 hours at 60∼100$^{\circ}C$. 1. The color intensity of the browning mixture heated at 100$^{\circ}C$ for 24 hours was the highest in tryptophanxylose, and in order to tryptophylglycine-xylose > lysine-xylose > leucylglycine-ylose > leucine-xylose > glycine-xylose. 2. The reaction rate constants (k) determined from the browning pigment concentrate with time were similar to the result of the color intensity, that is, the k were the highest in the tryptophan-xylose. 3. The residual amounts of dipeptides, amino acids and xylose in the browning mixture diminished as the browning temperature increase. 4. The activation energies (Ea) calculated from k were the highest in leucine-xylose (143.72 J/mol) and the lowest in tryptophan-xylose (117.45 J/mol). The range of Q$\sub$10/ values were 2.84∼3.58.

• 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.

• Journal of Microbiology and Biotechnology
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• 제10권4호
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• pp.564-567
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• 2000

A recombinant Saccharomyces cerevisiae, transformed with the genes encoding xylose reductase (XYL1) and xylitol dehydrogenase (XYL2) orginated from Pichia stipitis CBS 5776, was developed to directly convert xylose to ethanol. A fed-batch fermentation with the recombinant yeast produced 8.7 g ethanol/l with a yield of 0.13 g ethanol/g xylose consumed.