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변이주 Bacillus sp. A4442에 의한 갈락토스 전이활성이 높은 ${\beta}-Galactosidase$의 생산
최경호,양성준,김민홍,한금수,양지원,정진,인만진,Choi, Kyung-Ho,Yang, Sung-Joon,Kim, Min-Hong,Han, Keum-Soo,Yang, Ji-Won,Jung, Jin,In, Man-Jin 한국응용생명화학회 1995 Applied Biological Chemistry (Appl Biol Chem) Vol.38 No.6
토양으로부터 분리된 Bacillus sp.A1 균주는 가수분해활성보다는 전이활성이 훨씬 높은 ${\beta}-galactosidase$를 생산하기 때문에 산업적 응용 가능성이 있으나, glucose에 의한 catabolite repression을 보일 뿐만 아니라 lactose를 inducer로 요구한다는 결정적인 단점이 있어 갈락토올리고당의 제조에 직접 사용하기에는 적합하지 않았다. 따라서 galactose 전이효소의 생산성 제고를 꾀하기 위하여 N-methyl-N'-nitro-N-nitrosoguanidine를 이용한 3단계 변이를 시도하여 A4442변이주를 선발하였다. 이 변이주의 효소생산 능력은 괄목할 만큼 향상하였으며(약 20배 내외) catabolite repression과 lactose 요구성이 상당히 해제되었음을 확인하였다. 아울러 갈락토스가 새로운 inducer로 작용하는 것도 관찰하였다. 변이주를 이용한 발효시에 당의 농도와 배양액의 pH는 상호연관되어 효소의 생산에 영향을 끼쳤다. pH stat 기법을 이용하여 배양중 당의 농도를 0.5% 이하로 조절할 때 pH는 $6.5{\sim}7.5$ 범위내로 유지되었으며 효소활성은 $44\;unit/m{\ell}-broth$로 높게 나타났다. In an attempt to improve the productivity of ${\beta}-galactosidase$ from Bacillus sp. A1, which was isolated from soil and has remarkably higher transgalactosylation activity than lactose hydrolysis activity, a chemical mutation procedure using N-methyl-N'-nitro-N-nitrosoguanidine followed by selection was conducted. The final selection, designated as Bacillus sp. A4442, turned out to show a substantially increased enzyme productivity. Catabolite repression by glucose and lactose requirement as an inducer for the enzyme biosynthesis, which were shown in the parent strain, was markedly diminished; instead it was found out that galactose acts as another inducer. Because pH of medium, one of the most important factors for cell growth as well as enzyme production, is closely related with the sugar concentration during culture, it was kept in the optimum range of $6.5{\sim}7.5$; for this the initial glucose concentration was adjusted to be 0.5% which was thereafter maintained by the controlled pumping-in of lactose using the pH-stat technique. By doing so, we were able to increase the productivity of ${\beta}-galactosidase$ with high transgalactosylation activity up to $44\;unit/m{\ell}-broth$.
Sol-Gel 법으로 제조된 후막 PZT의 두께, 전극형상 및 분극공정에 따른 e₃₁, f 특성
박준식(Joon-Shik Park),양성준(Seong-Jun Yang),박광범(Kwang-Bum Park),윤대원(Dae-Won Yoon),박효덕(Hyo-Derk Park),김승현(Sung-Hyun Kim),강성군(Sung-Goon Kang),최태훈(Tae-Hoon Choi),이낙규(Nak-Kyu Lee),나경환(Kyoung-Hoan Na) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.4
Thick PZT films are required for the cases of micro actuators and sensors with high driving force,<br/> high breakdown voltage and high sensitivity, and so on. In this work, thick PZT films were fabricated<br/> by Sol-Gel multi-coating method. Total 8 types of samples using thick PZT films with thicknesses, about<br/> 1㎛ and 2㎛, and Pt top electrodes shapes for measuring transverse piezoelectric coefficient (e 31,f) were<br/> fabricated using MEMS processes. They were characterized by fabricated e31,f measurement system<br/> before and after poling. e31,f values of samples after poling were higher than before poling. Those of 2㎛<br/> thick PZT films were also higher than 1㎛ thick PZT films. And those with long electrodes as top<br/> electrodes were also higher than shorter.
변이주 Bacillus sp . A4442 에 의한 갈락토스 전이활성이 높은 β - Galactosidase 의 생산
인만진(Man Jin In),최경호(Kyung Ho Choi),양성준(Sung Joon Yang),김민홍(Min Hong Kim),한금수(Keum Soo Han),양지원(Ji Won Yang),정진(Jin Jung) 한국응용생명화학회 1995 Applied Biological Chemistry (Appl Biol Chem) Vol.38 No.6
In an attempt to improve the productivity of β-galactosidase from Bacillus sp. A1, which was isolated from soil and has remarkably higher transgalactosylation activity than lactose hydrolysis activity, a chemical mutation procedure using N-methyl-N`-nitro-N-nitrosoguanidine followed by selection was conducted. The final selection, designated as Bacillus sp. A4442, turned out to show a substantially increased enzyme productivity. Catabolite repression by glucose and lactose requirement as an inducer for the enzyme biosynthesis, which were shown in the parent strain, was markedly diminished; instead it was found out that galactose acts as another inducer. Because pH of medium, one of the most important factors for cell growth as well as enzyme production, is closely related with the sugar concentration during culture, it was kept in the optimum range of 6.5∼7.5; for this the initial glucose concentration was adjusted to be 0.5% which was thereafter maintained by the controlled pumping-in of lactose using the pH-stat technique. By doing so, we were able to increase the productivity of β-galactosidase with high transgalactosylation activity up to 44 U/㎖-broth.
화학 용액 증착 공정으로 제조된 후막 Pb(Zr_(0.52), Ti_(0.48))O₃의 e_(31,f) 특성
박준식,양성준,강성군,나경환 대한금속재료학회 2003 대한금속·재료학회지 Vol.41 No.9
Thick Pb(Zr_(0.52), Ti_(0.48))O₃(briefly, PZT) films are required for the cases of micro actuators and sensors with high driving force, high breakdown voltage and high sensitivity, and so on. In this work, thick PZT films were fabricated by chemical solution deposition process. Total 16 types of samples using thick PZT films with thicknesses, about 1 ㎛ and 2 ㎛, and Pt top electrodes shapes for measuring effective transverse piezoelectric coefficients (e_(31,f)) were prepared using MEMS processes. All samples were characterized by fabricated e_(31,f) measurement system before and after poling process at 125 kV/cm and 150℃ for 10 min. |e_(31,f)| values of samples after poling were higher than samples before poling. Those of 2 ㎛ thick PZT films were also higher than 1 ㎛ thick PZT films. We found that |e_(31,f)| was directly related with {111} to {h00} crystal structures of thick PZT films. And those with narrow electrodes (x₁- x_(0)) as top Pt electrodes were also higher than cases with wide top Pt electrodes in agreement with given equation.