• 한국미생물·생명공학회지
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• 제1권1호
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• pp.31-36
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• 1973

1. 화본과 작물의 짚 중에는 조섬유소, 즉, cellulose 및 hemicellulose 등 다당류의 양이 42∼55% 함유되어 있으며 동일작물이라도 품종이나 재배조건이 다르면 성분의 차이가 있었다. 2. 황산 당화액을 발효에 사용하려면 1∼2%의 황산으로 40psig에서 10분간 당화시키는 것이 가장 적당하였으며 이 때 당화율은 원료에 대하여 30∼35%이었다. 3. 황산당화에서 40psig이상으로 가열하면 hexose의 양은 증가하나 peotose의 양은 감소하였다. 이는 pentose가 furfural 등 발효저해 물질로 분해되기 때문이다. 4. 볏짚을 상압에서 2∼5%의 황산으로 가열하여 3∼5시간에 원료에 대하여 약 35%의 환원당이 생성되었다. 5. 40psig이하에서 얻은 당화액에서 Candida utilis NCYC 707을 배양하여 소비당의 50∼55% 균체를 생산하였으며 이 때 당소비는 초기 당의 90% 이상이었다.

• Journal of Microbiology and Biotechnology
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• 제23권9호
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• pp.1244-1252
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• 2013

Sugar beet pulp is an abundant industrial waste material that holds a great potential for bioethanol production owing to its high content of cellulose, hemicelluloses, and pectin. Its structural and chemical robustness limits the yield of fermentable sugars obtained by hydrolyzation and represents the main bottleneck for bioethanol production. Physical (ultrasound and thermal) pretreatment methods were tested and combined with enzymatic hydrolysis by cellulase and pectinase to evaluate the most efficient strategy. The optimized hydrolysis process was combined with a fermentation step using a Saccharomyces cerevisiae strain for ethanol production in a single-tank bioreactor. Optimal sugar beet pulp conversion was achieved at a concentration of 60 g/l (39% of dry weight) and a bioreactor stirrer speed of 960 rpm. The maximum ethanol yield was 0.1 g ethanol/g of dry weight (0.25 g ethanol/g total sugar content), the efficiency of ethanol production was 49%, and the productivity of the bioprocess was 0.29 $g/l{\cdot}h$, respectively.

• Journal of Microbiology and Biotechnology
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• 제26권7호
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• pp.1182-1189
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• 2016

Lactobacillus brevis ATCC 14869 exhibited a carbon catabolite derepressed phenotype that has ability to consume fermentable sugars simultaneously with glucose. To evaluate this unusual phenotype under harsh conditions during fermentation, the effects of lactic acid and hydrogen ion concentrations on L. brevis ATCC 14869 were examined. Kinetic equations describing the relationship between specific cell growth rate and lactic acid or hydrogen ion concentration were deduced empirically. The change of substrate utilization and product formation according to lactic acid and hydrogen ion concentration in the media were quantitatively described. Although the simultaneous utilization has been observed regardless of hydrogen ion or lactic acid concentration, the preference of substrates and the formation of two-carbon products were changed significantly. In particular, acetic acid present in the medium as sodium acetate was consumed by L. brevis ATCC 14869 under extreme pH of both acid and alkaline conditions.

• 한국식품영양학회지
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• 제10권3호
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• pp.360-364
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• 1997

멥쌀식혜에 Saccharomyces cerevisae를 가해 28$^{\circ}C$에서 10일간 발효시켜서 식혜주를 제조하였다. TLC 및 HPLC 분석 결과 발효에 따라 글루코오스는 하루, 말토오스는 4일, 말토트리오스는 6일까지만 존재하였다. 그러나, 분자량이 큰 말토올리고당과 한계덱스트린은 발효되지 않았다. 에탄올은 6.5%를 나타냈다. 식혜주의 아미노산 함량은 2.9$\mu$mol/ml, 단백질 함량은 457$\mu\textrm{g}$/ml를 나타냈다. pH는 3.67, 산도는 3.1ml를 나타냈다. 한계덱스트린은 1H-NMR로 분석 결과 식혜에 존재하는 것과 구조상 변화가 없었다. $\alpha$-1,4-결합에 대한 $\alpha$-1,6-결합의 비율도 5.6:1을 나타냈다. 관능검사 결과, 맛은 와인과 비슷하였다.

• KSBB Journal
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• 제29권4호
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• pp.297-302
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• 2014

The autoclaving assisted by an irradiation pretreatment method was developed without toxic chemicals to produce fermentable sugars for their conversion to bioethanol. In the first step, electron beam irradiation (EBI) of rice straw was performed at various doses. The electron beam-irradiated rice straw was then autoclaved with DI water at $120^{\circ}C$ for 1 h. A total sugar yield of 81% was obtained from 300 kGy electron beam-irradiated rice straw after 72 h of enzymatic hydrolysis by Cellulase 1.5L (70 FPU/mL) and Novozyme-188 (40 CbU/mL). Also, the removal of hemicellulose and lignin was 32.0% and 32.5%, respectively. This result indicates that the environmentally-friendly pretreatment method of rice straw by an electron beam irradiation could be applied for bioethanol production in plant.

• Journal of the Korean Wood Science and Technology
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• 제45권2호
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• pp.232-242
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• 2017

The objective of this study was to examine changes in the porosity and internal structure of wood as it goes through the process of saccharification (extraction of fermentable sugars). This study also examined the use of different drying methods to prepare samples for characterization of internal pores, with particular emphasis on the partially disrupted cell wall. Aspen wood flour samples after dilute acid pretreatment followed by enzymatic hydrolysis were examined for nitrogen adsorption. The resulting isotherms were analyzed for surface area, pore size distribution, and total pore volume. Results showed that freeze drying (with sample pre-freezing) maintains the cell wall structure, allowing for examination of saccharification effects. Acid pretreatment (hemicellulose removal) doubled the surface area and tripled the total volume of pores, which were mostly 10-20 nm wide. Subsequent enzymatic hydrolysis (cellulose removal) caused a 5-fold increase in the surface area and a ~ 11-fold increase in the total volume of pores, which ranged from 5 to 100 nm in width. These results indicate that nitrogen adsorption analysis is a feasible technique to examine the internal pore structure of lignocellulosic residues after saccharification. The information on the pore structure will be useful when considering value-adding options for utilizing the solid waste for biofuel production.

• Preventive Nutrition and Food Science
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• 제6권4호
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• pp.206-210
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• 2001

Starch is an abundant resource in plant biomass, and it should be hydrolyzed enzymatically into fermentable sugars for ethanol fermentation. A genetic recombinant yeast, Saccharomyces cerevisiae GA-7458, was constructed by integrating the structural gene of both $\alpha$-amylase from Bacillus stearothermophilus and the gene (STA1) encoding glucoamylase from S. diastaticus into the chromosome of S. cerevisiae SH7458. The recombinant yeast showed active enzymatic activities of $\alpha$-amylase and glucoamylase. The productivity of ethanol fermentation from the pH-controlled batch culture (pH 5.5) was 2.6 times greater than that of the pH-uncontrolled batch culture. Moreover, in a fed-batch culture, more ethanol was produced (13.2 g/L), and the production yield was 0.38 with 2% of corn starch. Importantly, the integrated plasmids were fully maintained during ethanol fermentation.

• 한국식품영양과학회지
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• 제44권8호
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• pp.1200-1205
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• 2015

본 연구에서는 최근 연구 결과들에 기초하여 발효성 당류인 FODMAP(fermentable oligosaccharides, disaccharides, monosaccharides, and polyols)이 설사와 높은 상관성을 가지고 있을 것이라 판단하였다. 따라서 상업용 메디컬푸드와 탄수화물 급원으로부터 FODMAP 함량을 측정하였다. 상업용 메디컬푸드의 단당류(fructose)와 이당류(lactose)의 함량 범위는 각각 ND~0.158, ND~0.304 g/200 mL였다. 삼당류(raffinose)와 사당류(stachyose)의 함량 범위는 각각 0.051~0.738, ND~0.579 g/200 mL였다. 또한 프럭토올리고당의 함량 범위는 1-kestose ND~0.413 g/200 mL, nystose ND~1.239 g/200 mL, 1-fructofuranosylnystose 0.205~0.458 g/200 mL였다. 탄수화물 급원 중 단당류(fructose)는 치커리 식이섬유($18.877{\pm}4.320g/kg$)에서만 검출되었으며, 이당류(lactose)는 모든 급원에서 검출되지 않았다. 삼당류(raffinose)의 함량은 치커리 식이섬유 $61.523{\pm}3.014g/kg$, 대두 식이섬유 $3.273{\pm}0.499g/kg$, 난소화성 말토덱스트린 $5.430{\pm}0.671g/kg$, 말토덱스트린(DE10~15, DE15~20)에서는 검출되지 않았다. 사당류(stachyose)의 함량은 치커리 식이섬유 $78.817{\pm}5.483g/kg$, 대두 식이섬유 $5.547{\pm}0.822g/kg$, 난소화성 말토덱스트린 $13.180{\pm}1.165g/kg$, 말토덱스트린(DE10~15) $16.440{\pm}0.370g/kg$, 말토덱스트린(DE15~20) $22.553{\pm}1.491g/kg$이었다. 프럭토올리고당(1-kestose, nystose, 1-fructofuranosylnystose)의 함량은 치커리 식이섬유 $29.369{\pm}2.553g/kg$, $39.430{\pm}6.740g/kg$, $50.407{\pm}2.642g/kg$, 대두 식이섬유 ND, ND, $18.647{\pm}0.397g/kg$, 난소화성 말토덱스트린 ND, $16.667{\pm}1.719g/kg$, $17.107{\pm}1.814g/kg$, 말토덱스트린 (DE10~15) ND, ND, $16.533{\pm}2.083g/kg$, 말토덱스트린 (DE15~20) ND, ND, $27.490{\pm}1.783g/kg$이었다. FODMAP은 탄수화물의 일종으로 메디컬푸드 제품의 탄수화물과 FODMAP 함량 간에 양의 상관관계를 가질 것으로 예상하였으나 r=0.55로 밀접한 상관성을 나타내지는 않았다. 국내외 메디컬푸드는 모두 유사한 원재료와 영양설계로 구성되어 있으나 사용되는 원재료의 종류에 따라 유래되는 FODMAP 함량이 다르기 때문에 제품 간의 함량 차이가 있는 것으로 생각된다. 본 연구에서 측정된 상업용 메디컬푸드 제품 및 탄수화물 급원의 FODMAP 함량 분석은 상대적으로 부족한 FODMAP 정량 분석 연구에 활용될 것으로 생각되며, 나아가 경관급식의 주요 부적응증인 설사를 최소화하는 메디컬푸드의 제품개발 및 원재료 선정에 기초 자료로 활용될 것이다.

• 한국미생물·생명공학회지
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• 제29권4호
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• pp.212-220
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• 2001

S. cerevisiae HBC52와 S, diataticus K114 의 rare mating 에 의해 개발된 HCS 균주들은 크기가 약 $13\mu\textrm{m}$ karyotype 분석결과 K114 균주에만 있는 약 1150kb 분자량을 가지는 염색체 band를 유지하였으며 전분을 분해하여 halo 를 형성하였다. Glucoamylase 활성은 약 2.7~3.4 unti/ml 를 가진 균주임이 밝혀졌으며 당 발효실험과 응집성 실험을 수행한 결과 HBC52 균주와 유사한 당 발효특성을 보이고 응집성 특성도 약응집성의 floculation type으로 비슷하였다. 그리고 HCS 균주의 포자형성과 피막형성 유무 실험에서는 양조효모인 HBC52 균주와 같이 포자가 형성되지 않았으며, 피막도 형성되지않았다. 균주들의 최종당도 실험은 HBC52균주가 약 68%의 발효수준을 나타냈고, HCS 균주들은 이 보다 높은 76~78%의 수준을 보였따. 즉 HBC52 균주가 최종당도($ 2.00^{\circ}$P)를 보인 반면 HCS 균주들은 ($0.7~0.93^{\circ}$P)를 보이는 결괄르 나타내어 맥주양조에서 low carbohydrate beer를 생산할 수있음이 확인되었다.

• Journal of Microbiology and Biotechnology
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• 제27권12호
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• pp.2165-2172
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• 2017

Lignocellulose is now a promising raw material for biofuel production. However, the lignin complex and crystalline cellulose require pretreatment steps for breakdown of the crystalline structure of cellulose for the generation of fermentable sugars. Moreover, several fermentation inhibitors are generated with sugar compounds, majorly furfural. The mitigation of these inhibitors is required for the further fermentation steps to proceed. Amino acids were investigated on furfural-induced growth inhibition in E. coli producing isobutanol. Glycine and serine were the most effective compounds against furfural. In minimal media, glycine conferred tolerance against furfural. From the $IC_{50}$ value for inhibitors in the production media, only glycine could alleviate growth arrest for furfural, where 6 mM glycine addition led to a slight increase in growth rate and isobutanol production from 2.6 to 2.8 g/l under furfural stress. Overexpression of glycine pathway genes did not lead to alleviation. However, addition of glycine to engineered strains blocked the growth arrest and increased the isobutanol production about 2.3-fold.