Streptomyces thermocyaneoviolaceus의 Xylanase 생산조건 및 Xylooligo당의 생산

주길재,박희동,최준호,이인구,이오석,권달호 慶北大學校農業科學技術硏究所 1998 慶北大農學誌 Vol.16 No.-

농산폐자원으로부터 기능성물질인 xylooligo당을 생산하기 위해서 내열성 균주인 S.thermocyaneoviolaceus가 생산하는 xylanase의 생산최적조건을 검토한 결과 0.8% 밀기울, 0.06% yeast extract, 0.06% bactopeptone, 0.05% MgSO₄·7H₂O, 0.005% FeSO₄·7H₂O, 0.05% KH₂PO₄및 0.2% K₂HPO₄를 함유한 배지(pH7.0)에서 50℃, 24시간 배양시 최고효소활성(2.47 unit/ml)의 배양상징액을 얻을 수 있었다. 효소의 최적반응조건은 pH5.5, 65℃였다. 또한 pH안정성을 조사한 결과 pH4.5∼9.5사이에서 4℃에서 12시간후에도 80% 이상의 효소활성을 유지하였고, 열 안정성은 60℃에서 1시간 처리후 94%이상의 효소활성을 유지하는 내열성이 있는 효소였다. 생산된 xylanase birchwood xylan 반응생성물을 TLC 및 HPLC로 확인해 본 결과, pH가 낮을수록(pH 5.0∼6.0) xylobiose와 xylotriose및 소량의 xylose의 양이 증가하였고, pH가 높을수록 (pH8.0∼9.0) X₄이상의 각종 xylooligo당의 양이 상대적으로 증가하였다. 또한 24 시간후에는 xylan의 상대량이 25% 이하로 감소하면서 주분해산물로 xylobiose가 생산되었으며 xylotriose와 xylose 및 X₄이상의 각종 xylooligo당이 생산되었다. A thermotolerant bacterium, Streptomyces thermocyaneoviolaceus which produced xylan-degrading enzymes, utilized excellently xylan of wheat bran by producing the enzymes in comparison with that of birchwood or oat spelts. Optimal enzyme production was achieved in WB medium containing 0.8% wheat bran, 0.06% yeast extract, 0.06% bactopeptone, 0.05% MgSO₄·7H₂O, 0.05% FeSO₄·7H₂O, 0.05% KH₂PO₄ and, 0.2% K₂HPO₄(pH 7.0) at 50℃ for 24 hrs. The optimal pH and temperature for the hydrolysis of xylan were pH 5.5 and 65℃, respectively. The enzyme activity was retained more than 80% at the range from pH 4.5 to pH 9.5 at 4℃ for 12 hrs and 94% on the heat-treatment at 65℃ for 1 hr. Xylobiose, xylotriose, xylose, and other xylooligosaccharides were produced as end products from hydrolysis of birchwood xylan by the xylanase of S. thermocyaneoviolceus.

반응표면분석에 의한 방선균 Streptomyces chibaensis J-59 포도당 이성화효소의 생산 최적화

주길재,박희동 慶北大學校農業科學技術硏究所 1996 慶北大農學誌 Vol.14 No.-

Jar fermentor 배양에서 S. chibaensis J-59로부터 포도당 이성화효소의 최적 생산조건을 확립하기 위하여 반응표면분석을 이용하였다. 실험계획은 중심계획합성법을 이용하였고, 3가지 실험요인으로는 공기주입량(vvm), 교반속도(rpm), 포도당의 농도(%)로 선별하였다. 요인실험의 결과로 회귀계수를 산출한 후 반응표면 회귀식을 구하였다. 효소 생산량의 변화에 대한 회귀식의 결정계수(R2)는 0.9776이였고, 분산분석의 F-ratio가 12.487이었으며, 이때 유의성(Prob>F)은 5% 이내로 인정되었다. 능선분석 결과, 효소생산 최대값은 공기주입량 2.227vvm, 교반속도 587.5rpm, glucose 농도 0.586%로 나타났으며 이때 반응표면 회귀식에 의해 추정하는 예상 효소활성은 7.67단위로 나타났다. Jar fermentor 배양에서의 최적화 회귀식에 따라 1% birchwood xylan, 1.5% CSL 0.1% MgSO₄·7H₂O, 0.012% CoCl₂·6H₂O, (pH 7.0)로 구성된 배지에 초기 pH를 7.0으로 조정하여 배양 종료까지 7.0을 유지하면서 공기주입량을 2.2vvm, 교반속도를 580rpm, glucose 농도를 0.586%로 하여 30℃에서 42시간 배양하였을 때 실제효소생산량은 7.43단위로 상기 분석법에서 예상한 효소 생산량의 97%에 달하였고, 플라스크배양의 효소생산량(2.78GIU/㎖)보다 약 2.7배 가량 효소생산이 증가되었다. Using response surface methodology(RSM), the various conditions(agitation speed, air flow. glucose concentration) in jar fermentor culture were investigated to find the optimum conditions for maximum enzyme production. Central-composite-design was used to control the variable constant in the experiment. The glucose isomerase production of Steptomyces chibaensis J-59 was mostly affected by the air flow rate and glucose concentration. The estimated optimum conditions were as follows: 1% birchwood xylan, 1.5% CSL, 0.1% MgSO₄·7H₂O, 0.012% CoCl₂·6H₂O, pH7.0; air flow, 2,2vvm; agitation speed, 587rpm; glucose concentration, 0.586%. Experimental values(7.43GIU/㎖) for the enzyme production obtained from the given optimum conditions had a almost resemblane to response values(7.67GIU/㎖) predicted by the RSM. The jar fermentor culture by the RSM produced xylose isomerase about 2.7 times as much as the baffled flask culture.

應力集中部에서의 破壞進路

朴熙代,金鍾周,曺相鳳 영남이공대학 1981 論文集 Vol.10 No.-

It was known by photoelastic and fracture experiments that the theory of fracture path of crack problems, fracture grows to the direction which the maximum shearing stresses arc minimum at the vicinity of crack tip, could be applied to the general stress concentration problems. That is the theory is like this, fracture initiation occurs at the maximum stress concentrated point and frature grows to the direction which the maxi-mum shearing stresses are minimum at the stress concentrated field.

소수성 촉매를 이용한 수소동위원소 교환 반응 측정을 위한 순환 반응기

최희주,이한수,안도희,강희석,김광락 한국공업화학회 2002 응용화학 Vol.6 No.2

The catalytic rate constants of hydrophobic catalysts developed for the removal of tritium mainly generated in the pressurized heavy water reactors should be measured. A recycle reactor was designed and built for characterzing the long-term behavior of the catalyst performance at the various temperatures and gas velocities.The catalytic rate constants were measured at the apparent gas velocity of 0.5 m/s and the temperature of 60℃. The initial catalytic constant was 8.44×10^-4mol/g.sec. This value is much greater than that considered in the design of Wolsong Tritium Removal Facility.

Logit 및 Turnbull 모형을 이용한 복숭아 품질인증의 소비자가치 평가

허주녕,김태균,변상희 한국농업정책학회, 한국축산경영학회 2000 농업경영정책연구 Vol.27 No.3

The dichotomous-choice contingent valuation method is applied to elicit consumers' value of quality-certificated peaches. First, a logit model is estimated like previous studies. Second, a distribution-free approach, Turnbull empirical distribution model, is employed to solve negative willingness to pay and truncation problems. The result is shown that consumers are willing to pay 2,559∼2,975 Won/kg more than the current price of regular peaches for quality-certificated peaches. Key words : 품질인증 복숭아(quality-certificated peach), 로짓모형(logit model), Turnbull 분포무관모형(Turnbull model), 가상가치평가(contingent valuation), 지불의사금액(willingness to pay)

Killer 효모 Saccharomyces cerevisiae B15-1의 에탄올 발효특성

이창호,우철주,이종수,정기택,박희동 한국미생물생명공학회 ( 구 한국산업미생물학회 ) 1996 한국미생물·생명공학회지 Vol.24 No.3

정치배양에 의한 Saccharomyces cerevisiae B15-1의 에탄올 발효에 미치는 영향 인자와 초기 기질농도에 따른 발효 특성을 연구, 검토하여 에탄올 생성 최적 조건하에서 발효액중의 생성된 에탄올 농도, 균체 농도 및 당 농도와의 관계를 규명하고자 하였다. 에탄올 생성의 최적 조건은 배양 온도 30℃, 초기 pH 5.0이었으며, 에탄올 비생성 속도는 초기 기질농도가 150 g/l일 때 1.203 g-EtOH/g-cell·hr로서 가장 높게 나타났다. 에탄올 발효능은 기질농도가 150 g/l 이하에서는 거의 일정하였으나 200 g/l에서는 급격히 감소하였다. 최종 균체량과 최종 에탄올 생성량은 초기 기질의 농도가 증가함에 따라 증가하는 현상을 보였으나 그 증가율은 기질의 농도가 높을 수록 다소 감소하는 경향을 나타내었다. 초기 기질농도가 150 g/l 이하에서는 대부분이 발효에 의해 에탄올로 전환되었으나 200 g/l의 당을 사용한 경우에는 균체의 증식과 발효가 완료된 후에도 약 10.7 g/l의 기질이 에탄올로 전환되지 못하고 배지에 남아 있었다. 초기 기질 농도를 매개변수로 생성된 에탄올과 에탄올 수율을 조사한 결과 에탄올 수율은 초기 당농도가 증가할수록 급격히 감소하였으며, 초기 당농도가 일정한 경우 에탄올 생성량이 소량일 때는 에탄올의 생성량이 증가할수록 에탄올의 수율은 급격히 증가하다가 점차 완만한 증가현상을 보였으며 에탄올 생성량이 60 g/l 이상에서는 거의 일정하였다. Characteristics of ethanol fermentation were investigated during the stationary culture of a killer yeast, Saccharomyces cerevisiae B15-1. Specific ethanol production rate reached the maximum level, 1.203 g-EtOH/g-cell·hr, at 150 g/l of the initial glucose concentration. No big differences were obtained in ethanol fermentability based on the initial sugar concentration below 150 g/l. When 200 g/l of sugar was used, fermentability dropped significantly. Although the final cell mass and the amount of ethanol produced were increased, their increase rates were declined according to the increase of initial sugar concentration. It was found that most of the sugar used below 150 g/l of concentration could be changed to ethanol. However, when 200 g/l of sugar was used, some of them remained in the media even after increase of cell mass and fermentation stopped. The ethanol yield was decreased when initial sugar concentration was high, and were increased when the amount of ethanol produced was increased and finally reached the plateau over 60 g/l of ethanol concentration.

초등과학 탐구수업 지도자료의 활용 실태

신영준,장명덕,배진호,권난주,여상인,이희순,노석구 한국초등과학교육학회 2005 초등과학교육 Vol.24 No.2

In this study, we had tried to present a plan for improving the actual conditions of practical utilization of teaching material for 6th grade science developed by Ministry of Education & Human Resources Development and distributed to all elementary schools in Korea. Also we presented ways of better utilization of the teaching material after investigating the actual conditions of practical utilization. A survey was made to investigate and collect all data in the major metropolitan cities, the Kangwon, Chungcheong, Honam, and Kyeongsang area, respectively. We surveyed 316 6th grader teachers to investigate the actual conditions of distribution and utilization of teaching material as a general research. In addition, we surveyed 46 teachers to investigate the organization and content of teaching material as a particular research. The results are as follows. First, the teaching material was not approximately transmitted and kept to 6th grader teachers. Second, the utilization guide was not made. Third, it was reported that the thematic divisions of teaching material was a strong point, but the less detailed experiment manual was a weak point. Fourth, the consideration of content difficulties and simplicity was necessary to improve the material. Fifth, additional items should be included in the introductory presentation, convenience of reorganization, activity material causing learning interest, guidance of substitution experiment, and more concrete notice of experiment activity. Finally, there were positive responses of more than 4.0 point of Likert scale (1 to 5 point scale) in detail investigations of thematic items, which could have possibility that the teaching material was helpful to elementary school science field.

2세대 Metal-on-Metal Prosthesis를 사용한무시멘트 인공 고관절 전치환술 중간 결과 보고 (5-10년)

김영창,정경칠,곽희철,김주용 대한고관절학회 2004 Hip and Pelvis Vol.16 No.1

방선균 WCM-9가 생산하는 Polyene 항진균성 항생물질(AF1)의 생물학적 성상

신운섭,정선호,이동희,이경호,김수기,박주영,고춘명 대한의진균학회 1996 대한의진균학회지 Vol.1 No.1

Background: Pathogenic fungi infect humans, especially immunocompromised patients, with superficial or deeply invasive pattern. In the past 20 years, fungal infections have been increased dramatically resulted by increment of organ transplantation, cancer, AIDS patients, or use of broad-spectrum antibacterial agents. Fungal infections are now important causes of morbidity and mortality of hospitalized patients. but there is no effective antifungal antibiotics as well as antibacterial antibiotics Objective: Effective new antifungal antibiotics are needed for the treatment of mycosis. So in an effort to develop effective antifungal antibiotics, we screened over 600 isolates of Streptomyces spp. from soil. Methods: Antifungal producing strain was selected using disk diffusion method, An antifungal substance (AF1) was purified with ethyl acetate extraction, silica gel column chromatography and reverse phase HPLC. MICs of AF1 were detected by agar dilition method. Results: The compound showed UV maxima of 307, 321, 340, 359 nm indicating methylpentaene. Minimum inhibitory concentrations of the AF1 were 3.7 ㎍/ml against mold, and 3.7 - 7.4 ㎍/ml against Candida species. AF1 was also active against Cryptococcus neoformans, with MIC of 0.9 ㎍/ml. The concentration of AF1 for K^+ ion release from human red blood cell and hemolysis were 5 ㎍/ml. Conclusion: The antibiotic purified from culture broth of Streptomyces sp. WCM-9 was a polyene antifungal antibiotic which have broad spectrum antifungal activity.

고리 및 영광 논토양에 대한 ^137Cs의 모의 사고 침적시 토양-벼 전이계수

최용호,임광묵,박효국,최희주,이한수 대한방사선 방어학회 2002 방사선방어학회지 Vol.27 No.4

고리 및 영광 원전 반경 5km 내 11곳의 논토양을 원상대로 재배상자에 채취하여 실험 온실로 운반한 후 벼의 이식 전과 생육중에 ^137Cs을 담수의 표면에 처리하였다. 이식전 처리시 ^137Cs의 토양-작물체 전이계수(m²kg^-1-dry plant)는 토양에 따라 8배 정도의 변이를 보였고 평균은 지역간 차이가 거의 없이 쌀알의 경우 1.1 x 10^-4 , 볏짚의 경우 2.7 x 10^-4 이었다. 분얼초기 처리와 수잉기 처리시 전이계수는 이식전 처리에 비해 대체로 2∼3 배 및 15∼30 배 정도 높았다. 토양 유기물 함량과 전이계수 간에는 정의 상관이 있었다. 본 실험결과에 입각하여 우리나라 논에 대한 일회성 사고침적시 적용할 수 있는 ^137Cs 전이계수의 대표치를 침적시기별로 제안하였다. Undisturbed soil blocks were taken into culture boxes from 11 paddy fields within 5 km radii of Kori and Yonggwang NPPs and carried to a greenhouse where ^137Cs was applied to the surface of standing water before rice transplanting and during its growth. Transfer factors (m²kg^-1-dry plant) of ^137Cs applied before transplanting varied with soils by a factor of about 8. The mean was 1.1 x 10^-4 for hulled rice seeds and 2.7 x 10^-4 for straw without significant regional differences. The ^137Cs applications at the early tillering stage and booting stage resulted in, on the whole, 2∼3 and 15∼30 times, respectively, higher transfer factors than the application before transplanting. A positive correlation was found between soil organic matter and transfer factor. Generic values of transfer factors were proposed for an acute accidental deposition of ^137Cs onto Korean paddy fields in different times of the year.