Aspergillus속이 생성하는 Pectin Esterase 의 효소학적 성질

유대식,송형익,정기택 한국균학회 1981 韓國菌學會誌 Vol.9 No.1

The enzymatic properties of pectin esterase from Aspergillus sp. were studied. The optimum conditions for the enzyme reaction were pH 4.2 and temperature of 45℃. The crude enzyme was very stable at pH range of 2.2∼4.6, but about 20 percent of activity was lost at the range of pH 5.4∼8.0. The crude enzyme was very stable at 50℃ for one hour, however almost 100 percent of enzyme activity was lost at 70℃ for 30 minutes. The pectin esterase activity of crude enzyme was greatly inhibited by addition of sodium chloride at lower pH range. That is, the inhibition rates of enzyme activity at pH 3.0 and 4.0 were 47% and 28% in concentration of 1M sodium chloride, respectively. The enzyme activity was not affected by sodium chloride at pH 7.0 at different concentration of sodium chloride. Although the enzyme activity was not affected by addition of sucrose, it was slightly inhibited at higher concentration of sucrose.

과실주 (果實酒) (사과주) 양조에 관한 연구 : 저농도주정함유 (低濃度酒精含有) 사과주에 관하여 Apple wine containing lower concentration of alcohol

유대식,홍순덕,송형익,정기택 한국균학회 1978 韓國菌學會誌 Vol.6 No.1

This study aims to brew apple wine containing lower concentration of alcohol by fermentation and to retain CO₂ gas in apple wine, and investigation for the possibility of storage at room temperature was performed. A Saccharomyces sp. was proved to be acceptable for production of base wine as its higher fermentation rate at 20∼25℃. However, B-2 was most reasonable for post-fermentation of apple wine as this strain strongly ferments sugars at low temperature (4℃). The yield of apple juice increased by maceration of apple pulps. The yield was about 5% more than that of the unmacerated juice, whereas acid content was decreased by 10% compared with control. When stored apple wine containing 9% alcobol was introduced 1∼3% sucrose at 7∼8℃ for 100 days or more, the CO₂ pressure of apple wine in bottle shows 3㎏/㎠ by bottle-pressure meter. It showed good storage of the wine at room temperature. CO₂ gas pressure in apple wine containing 6% alcohol, 5∼10% hop extract, and 2% sugar was 2㎏/㎠. he result also showed possibility of storage. Whereas 6% concentration of alcoholic apple wine without hop extract caused unusual fermentation during storage at the same condition. The desirable conditions for high quality apple wine should have CO₂ pressure of 2㎏/㎠ or more and should be added 1∼2% sugar to base wine. From these results, it can be concluded that the brewing of lower alcoholic apple wine is possible.

카드뮴 내성 Hansenula anomala B-7의 단백질 합성에 미치는 카드뮴의 영향

유대식,송형익 한국미생물 · 생명공학회 1990 한국미생물·생명공학회지 Vol.18 No.3

카드뮴 내성 효모, Hansenula anomala B-7 세포에 축적된 카드뮴의 세포내 분포와 단백질 합성에 미치는 카드뮴의 영향 등에 대하여 연구하였다. 세포내 축적된 카드뮴의 84.9는 cytosol 등인 가용성 분획에 존재했다. 세포내 단백질 함량은 카드뮴(1,000$\mu g$0/ml)에 의하여 감소되었으나, 유안(30-75 포화)에 의하여 침전되는 가용성 단백질의 함량은 카드뮴에 의하여 증가되었다. 더욱이 카드뮴(1,00$\mu g$0/ml)의 첨가배지에서 배양된 세포에는 고분자 가용성 단백질이 카드뮴 무첨가 배지에서 배양된 세포에서 보다 증가되었으나, 저분자 단백질은 감소되었다. 이상의 결과로 단백질의 합성은 카드뮴에 의하여 저해되나, 유안(30-75 포화)에 의하여 침전되는 고분자 단백질의 합성은 카드뮴에 의하여 촉진된다. In this study the authors investigated the distribution of cadmium accumulated in cadmium-iun tolerant Hansenula anomala B-7 cells and also the effect of cadmium on protein synthesis. 84.9% of the cadmium accumulated was distributed in the soluble fraction (cytosol, etc.). The intracellular protein content was decreased by cadmium (1,000 $\mu g$/ml), but the content of soluble protein preeipitated by ammonium sulfate (30-75% saturation) was increased compared with the content of it obtained from the cells grown without cadmium. Furthermore, in the cells grown with 1,000 $\mu g$/ml of cadmium t h higher molecular weight soluble protein was increased compared with the cells grown without caa, mium, but the lower molecular weight soluble protein was decreased. These results suggested that the protein synthesis was inhibited by cadmium, but synthesis of higher molecular weight soluble protein was remarkably stimulated by cadmium.

Streptococus zooepidemicus에 의한 히아루론산의 생산

유대식 한국생물공학회 1992 KSBB Journal Vol.7 No.2

Streptococcus zooepidemicus에 의한 hyaluronic acid 생성의 최적 배지 조성은 batch cultre 조건에서 0.1% 쇠고기 추출물, 0.1% 효모 추출물, 3.0% 포도당 2.0% peptone, 0.1% 식염 및 0.5% $CaCO_3$이였으며, 배지의 포기 pH는 7.5로서 $37^{\circ}C$에서 36시간 진탕배양하는 것이 양호했다. 특히 공시균의 생육에 수반되어 hyaluronic acid가 생성되므로 배지의 pH를 중화하기위해 $CaCO_3$의 첨가는 필수적이었다. An optimal composition of medium for hyaluronic acid production and some characteristics of its from Streptococcus zooepidemicus were investigated. The hyaluronic acid from S. zooepidemicus was reached maximum level in the BY-medium containing 0.1% beef extract, 0.1% yeast extract, 3.0% glucose, 2.0% peptone, 0.1% NaCl and $0.5%CaCO_3$ (pH 7.5) at $37^{\circ}C$ for 36 hours with shaking. Addition of $CaCO_3$ to the medium was necessary to neulralize the lowered pH which was resulted from hyaluronic acid production. Molecular weights of extracelluar and cellular hyaluronic acid produced by the strain were $1-1.4{\times }10^6$ and $5{\times}10^6$, respectively. The amount of extracellular hyaluronic acid was 91.9% of total hyaluronic acid produced and the vest was all intracellular.

세포외 Cytosine Deaminase 생산균의 분리 및 동정

유대식,김대현 한국산업미생물학회 1997 한국미생물·생명공학회지 Vol.25 No.1

토양으로부터 세포의 cytosine deaminase를 다량 생산하는 YK 391 세균을 분리하였다. 이 세균의 형태적 특징은 포자를 형성하지 않고 운동성을 가지는 그람음성간균으로서 통성혐기성 세균이었다. 생리적 특징은 esculine을 가수분해하지 않으며 포도당과 trehalose로부터 산을 생성하나 arabinose로 부터는 산을 생성하지 않으며, 세포의 지방산은 palmitoleic acid와 palmitic acid가 80.31였으며 4℃에서 생육하지 않고 37℃에서 생육하므로, Chromobacterium violaceum YK 391로 동정했다. Chromobacterium violaceum YK391이 생산하는 세포와 cytosine deaminase는 cytosine과 5-fluorocytosine뿐 아니라 cytidine도 탈아미노화 시켰다. A bacterium, strain YK 391 producing extracellular cytosine deaminase, has been isolated from soil sample collected near Taegu City and identified. The strain YK 391 was observed to be a motile Gram-negative rod, and did not produced capsule nor spore. The bacterium produced acid from glucose and trehalose not from arabinose. Esculine was not hydrolyzed. The isolate could grow anaerobically at 37℃, but not at 4℃. Palmitoletic and palmitic acids comprised over 80% of the fatty acid composition of the strain. The strain YK 391 was identified as Chromobacterium violaceum YK 391 based on its morphological and physiological characteristics, and on the fatty acid composition. The extracellular cytosine deaminase produced by Chromobacterium violaceum YK 391 is believed to be unique because it was active not only on cytosine and 5-fluorocytosine but also on cytidine.

Bacillus polymyxa YL38-3의 세포외 cytosine deaminase 생성의 최적 배양 조건

유대식,김대현,박정문,송형익,정기택 한국미생물학회 1988 미생물학회지 Vol.26 No.4

The strain YL 38-3, which was capable of producing extracellular cytosine deaminase, was isolated and taxonomically examined. The isolated strain was identified to be Bacillus polymyxa YL 38-3. The optimal conditions for the enzyme production from Bacillus polymyxa YL 38-3 were investigated. The enzyme production was reached maximum level in the medium containing 0.5% glucose, 0.2% beef extract, 0.5% NaCl and 0.1% $KH_{2}PO_{4}$ (pH 6.0). And the enzyme showed the highest activity when the strain YL 38-3 was cultivated at $35^{\circ}C$ for 24 gours under the initial pH 6.0. By the additions of peptone the extracellular enzyme production was inhibited, meanwhile the intracellular enzyme production was highly stimulated. It was, therefore, deduced that peptone was related to the secretion mechanism of the enzyme from this bacterial cell.

카드뮴 내성 효모의 세포내 카드뮴 축적 기작

유대식,송형익,정기택 한국미생물 · 생명공학회 1990 한국미생물·생명공학회지 Vol.18 No.3

The mechanism of intracellular accumulation of cadmium in a cadmium-ion tolerant yeast, Hansenula ammala B-7, which is an extreme cadmium tolerant strain and has the ability to take up a large amount of cadmium was investigated. The amounts of cadmium taken up by the scalded yeast cells were 2 to 3 times more than the value of the living cells. The living Hansenula anomala B-7 cells adsorbed 74% of cadmium taken up onto the other layer of the cells and 26% of it accumulated inside the cells. But the scalded cells adsorbed 98.3% of cadmium taken up and accumulated 1.7% of it inside the cells. A cadmium uptake and its accumulation were accelerated up to 162.3% and 275.4% by Triton X-100 in the living cells, respectively. Whereas in the scalded cell cadmium uptake was not affected by Triton X-100. Furthermore the cadmium uptake and its accumulation were strongly inhibited by metabolic inhibitors like 2,4-dinitrophenol, sodium azide and potassium cyanide in the living cells, but in the scalded cells cadmium uptake was not affected by metabolic inhibitors. These results suggested that the intracellular accumulation of cadmium by the cadmium-tolerant Hansenula anomala B-7 cells was apparently dependent of biological activity, and also gave evidence of the existance of energy-dependent system.

카드뮴의 Hansenula anomala 세포내 축적에 미치는 Triton X-100의 효과

유대식,박정문,송형익 한국미생물학회 1987 미생물학회지 Vol.25 No.2

고도 카드뮴 내성효모 Hansenula anomala B-7의 균체내에 다량의 카드뮴을 축적시키기 위하여 배양시 계면활성제를 첨가하여 배양하는 방법을 검토했다. 계면활성제 중 비이온계인 Triton X-100에 의하여 약 40%의 카드뮴의 축적효과를 나타내며 유효농도는 0.1-0.2%였다. 균체내 카드뮴 축적의 최적조건은 다음과 같다. 정치배양보다 진탕배양이 효과적이었으며, 48시간 진탕배양으로 카드뮴의 균체내 축적이 최대에 도달했으며 배지의 초기 pH는 6.0이었으며, 배양온도는 $40^{\circ}C$가 양호했다. As a pary of investgation on effective accumulation of cadmium in yeast cells, effect of surfactant was studied on intracellular accumulation of cadmium in extremely cadmium-tolerant yeast, Hansenula anomala B-7. Cadmium accumulation was enhanced up to approximately 40% by the addition of non-ionic surfactant, Triton X-100 and its optimal concentration was found to be 0.1-0.2%. Furthermore, optimum conditions for intracellular accumulation of cadmium were at $40^{\circ}C$ and initial pH 6.0 for 48 hours under shaking culture.

국내 사용후핵연료 전과정 안전규제현황 및 개선방향

유대식,박동극,이관희,이복형,정승영,이상민,정찬우 대한방사선방어학회 2012 대한방사선방어학회 학술발표회 논문요약집 Vol.2012 No.11

세포외 Cytosine Deaminase의 효소학적 성질

유대식,김대현,박정문,송형익,정기택 한국미생물학회 1988 미생물학회지 Vol.26 No.4

Bacillus polymyxa YL38-3이 생성하는 세포의 cytosine deaminase의 효소학적 ,성질을 검토하였다. 본 세포외 효소는 열 안정성이 높으며, 인산완충액(pH6.0)과 $30^{\circ}C$에서 효소활성이 최대를 나타냈다. 본 효소는 cytosine 뿐 아니라 5- fluorocytosine-을 기질로 하나, 5-methylcytosine은 촉매하지 않았다. 더우기 본 효소는 $Cd^{2-}$, $Hg^{2+}$의 중금속이온과 ImM p-chloromercuribenzoate에 의하여 완전히 실활되며, o-phenanthroline과 monoiodoacetate에 의하여 75% 저해되었다. 그러나 1mM 2-mercaptoethanol에 의하여 본 효소의 활성을 약 200% 이상 활성화시켰다. Enzymological proprties of an extracellular cytosine deaminase from Bacellus polymyxa YL 38-3 were investigated. The extracellular enzyme was very stable, and optimum pH and temperature for the enzyme activity were found to be near pH 6.0 in 0.2M potassium phosphate buffer and at $30^{\circ}C$, respectively. 5-Fluorocytosine was converyed to 5-fluorouracil by the enzyme, but 5-methylcytosine was not to thymine by it. The enzyme activity was completely inhibited by some heavy metal ion such as 1mM of $Cd^{2-}$ and $Hg^{2+}$, and by 1mM of p-chloromercuribenzoate, respectively. The enzyme activity was inactivated about 75% by 1mM of o-phenanthroline and monoiodoacetate. But the enzyme activity was stimulated up to 200% by 1mM of 2-mercaptoethanol.