• 한국미생물생명공학회:학술대회논문집
• /
• 한국미생물생명공학회 1978년도 추계학술대회
• /
• pp.206.4-206
• /
• 1978

By utilizillg whole cell enzyme of the Xantho-monas citri IFO 3835, cephalexin is synthesized directly from 7-amino-deacetoxy cephalosporanic acid (7-ADCA) and phenyl glycine methyl ester (PGM). To date, cephalexin has been manufactu-red by chemical process involving fairly large number of steps to protect the amino group of phenly glycine and carboxyl group of 7-ADCA. However, the enzymatic process involves only a single step with 85％ conversion in 90 minutes. The fermentation variables studied indicate that oxygen transfer is limiting step in the enzyme production. Optimum conditions for enzymatic reaction were 37 C, pH 6.0, and the optimum substrate molar ratio of PGM to 7-ADCA was 2. Other variables that are related to the biochemical properties of whole cell enzyme temperature stability, pH stability, kinetic constants, reusing effect, enzyme loading effect were also evaluated.

• BMB Reports
• /
• 제37권4호
• /
• pp.503-506
• /
• 2004

Glucose-1-phosphate uridylyltransferase from E. coli K12 was used to convert uridine-5'-triphosphate and glucose-1-phosphate to UDP-D-glucose. The conversion was efficient and completed within 5 minutes under the employed conditions. In addition, thymidine-5'-monophosphate kinase and acetate kinase were proven to be non-specific, converting udridine-5'-monophosphate to uridine-5'-triphosphate with 55% conversion after 6 h, which was much slower than the production of TTP under the same conditions (complete conversion within one hour). Since these two reactions could proceed under the same conditions, a one-pot synthesis of UDP-D-glucose with ATP regeneration was designed from easily available starting materials, and conversion up to 40% by HPLC peak integration was achieved given a reaction time of 4 h.

• 한국균학회지
• /
• 제14권3호
• /
• pp.195-200
• /
• 1986

Rhizopus japonicus의 한 균주가 생산하는 효소에 의해 인삼 사포닌의 ginsenoside 중 조성비율이 가장 큰 ginsenoside $Rb_1$을 약리 효능면에서 보다 우수한 ginseuoside $Rb_1$로 선택적으로 전환할 수 있음을 TLC 및 HPLC로 정량적으로 확인하였다. Total saponin을 기질로 사용하였을 경우 ginsenoside $Rb_1$은 그 함량의 82.5%까지 ginsenoside Rd로 전환되어 ginsenoside Rd의 함량을 원래 함량에 비해 4.75배까지 증가시킬 수 있었으며, ginsenoside-Rb group saponin 기질의 경우는 80.8%의 ginsenoside $Rb_1$이 ginsenoside Rd로 전환되어 ginsenoside Rd의 함량을 34.7배까지 처리효소의 농도에 비례해서 증가시킬 수 있었다. 한편 다른 ginsenoside 함량변화 없이 오직 ginsenoside $Rb_1$에서 ginsenoside Rd만으로 선택적 전환을 한다는 사실이 당이나 sapogenin의 검출로도 증명되었다.

• 한국식물학회:학술대회논문집
• /
• 한국식물학회 2001년도 춘계학술발표대회:발표눈문요지록
• /
• pp.26-26
• /
• 2001

• Journal of the Korean Wood Science and Technology
• /
• 제48권5호
• /
• pp.651-665
• /
• 2020

Hydrolysis of biomass for the production of fermentable sugar can be improved by the addition of surfactants. In pulp and paper mills, lignin, which is a by-product of the pulping process, can be utilized as a fine chemical. In the hydrolysis process, lignin is one of the major inhibitors of the enzymatic breakdown cellulose into sugar monomer. Therefore, the conversion of lignin into a biosurfactant offers the opportunity to solve the waste problem and improve hydrolysis efficiency. In this study, lignin derivatives, a biosurfactant, was applied to enzymatic hydrolysis of various lignocellulosic biomass. This Biosurfactant can be prepared by reacting lignin with a hydrophilic polymer such as polyethylene glycol diglycidylethers (PEDGE). In this study, the effect of biosurfactants on the enzymatic hydrolysis of pretreated sweet sorghum bagasse (SSB), oil palm empty fruit bunch, and sugarcane trash with different lignin contents was investigated. The results show that lignin derivatives improve the enzymatic hydrolysis of the pretreated biomass with low lignin content, however, it has less influence on the enzymatic hydrolysis of other pretreated biomass with lignin content higher than 10% (w/w). The use of biosurfactant on SSB kraft pulp can increase the sugar yield from 45.57% to 81.49%.

• Journal of Forest and Environmental Science
• /
• 제36권2호
• /
• pp.69-77
• /
• 2020

Lignocellulosic biomass has recalcitrant characteristics against chemical and biological conversion due to its structural heterogeneity and complexity. The pretreatment process to overcome these recalcitrant properties is essential, especially for the biochemical conversion of lignocellulosic biomass. In recent years, pretreatment methods using ionic liquids (ILs) and deep eutectic solvents (DESs) as the green solvent has attracted great attention because of their advantages such as easy recovery, chemical stability, temperature stability, nonflammability, low vapor pressure, and wide liquids range. However, there are some limitations such as high viscosity, poor economical feasibility, etc. to be solved for practical use. This paper reviewed the research activities on the pretreatment effect of various ILs including DESs and their co-solvents with organic solvents on the enzymatic saccharification efficiency of lignocellulosic biomass and the nanocellulose preparation from the pretreated products.

• 한국생물공학회:학술대회논문집
• /
• 한국생물공학회 2005년도 생물공학의 동향(XVII)
• /
• pp.511-516
• /
• 2005

Sorbitan methacrylate was synthesized from sorbitan dehydrated from D-sorbitol using an immobilized lipase. To optimize the enzymatic synthesis of sorbitan methacrylate, response surface methodology was applied to determine the effects of five-level-four-factors and their reciprocal interactions on sorbitan methacrylate biosynthesis. A total of 30 individual experiments were performed, which were designed to study reaction temperature, reaction time, enzyme amount and substrate molar ratio. A statistical model predicted that the highest conversion yield of sorbitan methacrylate was 100%, at the following optimized reaction conditions: a reaction temperature of 43.06 $^{\circ}C$, a reaction time of 164.25 mins., an enzyme amount of 7.47%, and a substrate molar ratio of 3.98:1. Using these optimal factor values under experimental conditions in four independent replicates, the average conversion yield reached 98.7%${\pm}$1.2% and was well within the value predicted by the model.

• 한국식품영양과학회지
• /
• 제11권4호
• /
• pp.13-16
• /
• 1982

성장이 빠르며 임산가공학적으로 많이 이용되지 않고 있는 이태리 포플라를 이용하여 6탄당과 5탄당으로 가수분해를 시켰으며 다음과 같은 결과를 얻었다. 기질을 산으로 가수분해 시킨결과 황산 농도 15%에서 1시간 작용시에는 14.82%, 산과 효소 가수 분해시에는 산 농도 20%에서 3시간 처리시 20.20%가 분해되었다. NaOH의 알카리로 처리시에는 1%의 농도 3시간이 지나 9.8%의 분해도를 보였고, 알카리 효소 처리시에는 10.48%까지 분해되었다. 또한 이와같은 실험에서 톱밥 가수분해에 대한 최적조건은 $H_2SO_4$ 25%의 농도에서 3시간 처리후 또한 3시간동안 효소처리를 받았을때 기질 100g으로 부터 10.70g의 당이 생성되었음을 확인하였다.

• Journal of Microbiology and Biotechnology
• /
• 제9권5호
• /
• pp.646-649
• /
• 1999

A thermophilic bacterium producing D-stereospecific dipeptidase was isolated from Korean soil samples. The enzyme hydrolyzed the peptide bond between D-alanyl-D-alanine (D-Ala-D-Ala). The isolated bacterial strain was rod shaped, gram-positive, motile, and formed an endospore. Morphological and physiological characteristics suggested this microorganism a thermophilic Bacillus species, and was named as Bacillus sp. BCS-l. The production of D-stereospecific dipeptidase was growth-associated and optimal at $55^{\circ}C$. The enzyme was applied for the synthesis of D-amino acid-containing peptide, N-benzyloxycarbonyl-L-aspartyl-D-alanine benzyl ester (Z-L-Asp-D-AlaOBzl), as a model reaction. A thermodynamically controlled synthesis of Z-L-Asp-D-AlaOBzl was achieved in an organic solvent.

• KSBB Journal
• /
• 제19권5호
• /
• pp.385-389
• /
• 2004

In this research, the chemo-enzymatic synthesis of sorbitan methacrylate was investigated to optimize reaction conditions. Firstly, sorbitan was manufactured by sorbitol cyclic reaction in the presence of p-toluenesulfonic acid (p-TSA) as catalyst material. Secondly, sorbitan methacrylate was synthesized by immobilized lipase Novozyme 435 with acyl donors in t-butanol. As a result of enzymatic synthesis of sorbitan methacrylate, the conversion yield reached about $65\%$ in the condition of initial sorbitan conc. 50 g/L, enzyme content $3\%$ (w/v) , molar ratio 1:3, reaction temperature 50^{circ}C and reaction time 42 hrs using methyl methacrylate as acyl donor. Comparing with acyl donors and reaction temperature, the conversion yield reached about 18, 65 and $80\%$ with methacrylic acid, methyl methacrylate and vinyl methacrylate as acyl donor, respectively. And optimum reaction temperature was 60, 50, and 50^{circ}C, respectively