• 한국균학회소식:학술대회논문집
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• 한국균학회 2015년도 추계학술대회 및 정기총회
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• pp.16-16
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• 2015

Ectomycorrhizal (ECM) mushrooms play a major role in plant growth promotion through symbiotic association with roots of forest trees. They also provide an economically important food resource to us and therefore they have been studied for their artificial cultivation for decades in Korea. We have secured bio-resources of ECM mushrooms from Korean forests and performed their physiological studies. To investigate the cultural characteristics, the fungi were cultured under different conditions (medium, temperature, pH of the medium, inorganic nitrogen source). More than 90% of total 160 strains grew on three solid media (potato dextrose agar, PDA; sabouraud dextrose agar, SDA; modified Melin-Norkrans medium, MMN). The rate of mycelial growth on malt extract agar (MEA) was lower than those of three media (PDA, SDA, MMN). None of the Tricholomataceae strains grew on MEA. Many strains of ECM mushrooms were able to grow at the temperature range of $15{\sim}25^{\circ}C$ on PDA, while they showed poor growth at $10^{\circ}C$ or $30^{\circ}C$. In particular, the growth rates of both Gomphaceae and Tricholomataceae were significantly lower at $10^{\circ}C$ than at $30^{\circ}C$. The optimal pH of many strains was pH 5.0 when they cultured in potato dextrose broth (PDB). Fifty-seven percent of tested strains grew well on medium containing ammonium source than nitrate source. Many strains of Tricholomataceae showed a notable growth on ammonium medium than nitrate medium. Twenty-three percent of strains preferred nitrate source than ammonium source for their mycelial growth. The production and activity of two enzymes (cellulase and laccase) by ECM fungi were also assayed on the enzyme screening media containing CMC or ABTS. Each strains exhibited different levels of enzymatic activities as well as enzyme production. The number of laccase-producing strains was less than that of cellulase-producing strains. We found that 77% of tested strains produced both cellulase and laccase, whereas 2% of strains did not produce any enzymes. The morphological characteristics of mycelial colony were also examined on four different solid media. Yellow was a dominant color in mycelial colony and followed by white and brown on all culture media. ECM mushrooms formed mycelial colonies with a single or multiple colors within a culture medium depending on the strains and culture media. The most common shape of mycelial colony was a circular form on all media tested. Other families except for Amanitaceae formed an irregular colony on MMN than PDA. All strains of Tricholomataceae did not form a filamentous colony on all media. The pigmentation of culture media by mycelial colonies was observed in more than 50% of strains tested on both PDA and SDA. The degree of pigmentation on PDA or SDA was higher than MMN and brown color was dominant than yellow color. The production of exudates from mycelial colony was higher on PDA than MMN. Brown exudates were mainly produced by many strains on PDA or SDA, whereas transparent exudates were mainly produced by strains on MMN. We observed the mycelial colonies with a single or multiple textures in just one culture plate. Wrinkled or uneven colony surfaces were remarkably observed in many strains on PDA or SDA, while an even colony surface was observed in many strains on MMN. Sixty percent of Tricholomaceae strains formed wrinkled surface on PDA. However, they did not form any wrinkle on MMN plate. Cottony texture was observed in mycelia colonies of many strains. Velvety texture was often observed in the mycelial colonies on SDA than PDA and accounted for 60% of Suillaceae strains on SDA.

• Biotechnology and Bioprocess Engineering:BBE
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• 제10권6호
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• pp.482-493
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• 2005

Biomass is originally photosynthesized from inorgainic compounds such as $CO_2$, minerals, water and solar energy. Recent studies have shown that anaerobic bacteria have the ability to convert recalcitrant biomass such as cellullosic or chitinoic materials to useful compounds. The biomass containing agricultural waste, unutilized wood and other garbage is expected to utilize as feed, food and fuel by microbial degradation and other metabolic functions. In this study we isolated several anaerobic, cellulolytic and chitinolytic bacteria from rumen fluid, compost and soil to study their related enzymes and genes. The anaerobic and cellulolytic bacteria, Clostridium thermocellum, Clostridium stercorarium, and Clostridium josui, were isolated from compost and the chitinolytic Clostridium paraputrificum from beach soil and Ruminococcus albus was isolated from cow rumen. After isolation, novel cellulase and xylanase genes from these anaerobes were cloned and expressed in Escherichia coli. The properties of the cloned enzymes showed that some of them were the components of the enzyme (cellulase) complex, i.e., cellulosome, which is known to form complexes by binding cohesin domains on the cellulase integrating protein (Cip: or core protein) and dockerin domains on the enzymes. Several dockerin and cohesin polypeptides were independently produced by E. coli and their binding properties were specified with BIAcore by measuring surface plasmon resonance. Three pairs of cohesin-dockerin with differing binding specificities were selected. Two of their genes encoding their respective cohesin polypeptides were combined to one gene and expressed in E. coli as a chimeric core protein, on which two dockerin-dehydrogenase chimeras, the dockerin-formaldehyde dehydrogenase and the dockerin-NADH dehydrogenase are planning to bind for catalyzing $CO_2$ reduction to formic acid by feeding NADH. This reaction may represent a novel strategy for the reduction of the green house gases. Enzymes from the anaerobes were also expressed in tobacco and rice plants. The activity of a xylanase from C. stercorarium was detected in leaves, stems, and rice grain under the control of CaMV35S promoter. The digestibility of transgenic rice leaves in goat rumen was slightly accelerated. C. paraputrificum was found to solubilize shrimp shells and chitin to generate hydrogen gas. Hydrogen productivity (1.7 mol $H_2/mol$ glucos) of the organism was improved up to 1.8 times by additional expression of the own hydrogenase gene in C. paraputrficum using a modified vector of Clostridiu, perfringens. The hydrygen producing microflora from soil, garbage and dried pelletted garbage, known as refuse derived fuel(RDF), were also found to be effective in converting biomass waste to hydrogen gas.

• 자원환경지질
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• 제50권1호
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• pp.27-34
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• 2017

제강 환원슬래그(steelmaking reduction slag)를 출발물질로 사용하여 다양한 농도의 $H_2SO_4$, $NH_4NO_3$(0.3, 0.5, 0.7, 1 M) 용액, 반응온도 $100^{\circ}C$와 $150^{\circ}C$의 조건에서 Ca 용출 및 탄산화 실험을 실시하였다. 양이온 용출과 탄산화 반응시간은 각각 2시간 및 1시간이었으며 탄산화 효율 증대를 위해 pH는 약 12로 조절하였고 $CO_2$의 부분압은 10 bar이었다. TG 분석결과로부터 탄산화율을 계산한 결과, $H_2SO_4$ 0.5 M과 반응온도 $150^{\circ}C$의 실험 조건에서 약 86%의 고정화율이 관찰되었으나 이 이상의 농도에서는 탄산화율은 급격히 감소하였다. 그러나 $NH_4NO_3$용액을 사용한 결과, 산의 농도가 증가함에 따라 탄산화율도 비례적으로 증가하여 1 M 농도에서 약 93%의 탄산화율이 관찰되었다. 따라서 제강 환원슬래그를 사용한 탄산화반응은 $H_2SO_4$보다는 $NH_4NO_3$용액을 사용할 경우 유리한 것으로 분석되었다. SEM 분석결과, 합성된 아라고나이트는 나무토막 형태(wood piece shape), 둥근형태(round shape), 꽃모양(flower shape)으로 관찰되었으며, 방해석은 결정면이 잘 발달된 능면체형(rhombohedral shape)의 전형적인 형태로 확인되었다.

• 대한기관식도과학회:학술대회논문집
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• 대한기관식도과학회 1976년도 제10차 학술대회연제 순서 및 초록
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• pp.87.4-88
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• 1976

본 의료원 개원이래 1971년 11월부터 1976년 3월말까지 만 4년 5개월간 경희대학교 부속병원 이비인후과에 내원한 식도이물환자 73례, 기도이물환자 8례, 총 81례에 대한 통계적 고찰을 하여 다음과 같은 결론을 얻은바 기왕의 보고와 비교관찰 하면서 문헌적 고찰과 함께 보고하는 바이다. 결론은 다음과 같다. 1) 식도이물의 빈도는 총례 73례중 주화(61례 : 83.6%) 골편 (6례 : 8.2%) 식괴(3례 ; 4.1%) 디스크 나른 금속들의 순이었고, 기도이물 총 8례중 석괴(3례 ; 37.5%) 금속편(2례 ; 25%), 플라스틱제 연필뚜껑, 나무조각, 플라스틱제반지의 순서였다. 2) 성별비는 남자가 51례(62.9%) 여자가 30례(37.1%)이며 남녀비는 약 1.7:1로 남자에 많았다. 3) 연령별로는 5세이하가 총 81례중 69례(85.2%)였으며 특히 주화는 5세이하가 61례중 59례(96.7%)였으며 최고 연령은 8세 최저연령은 11개월이었다. 기도 이물은 8례 중 7례(87.5%)가 10세이하의 어린이었다. 4) 식도이물과 기도이물의 비는 식도이물 73례, 기도 이물 8례로 약 9:1로 식도이물이 많았으며, 부위별로는 식도이물에서 66례(90.4%)가 제1협착부에, 5례(6.9%)가 제2협착부에, 그리고 2례(2.7%)가 제3협착부에 있었다. 기도이물에서는 5례(62.5%)가 기관에, 2례가 후두에 그리고 1례는 기관지에 있었다. 5) 잔류기간에 있어서 식도이물은 24시간이내가 63례(86.3%)였으며 1례는 16일동안 잔류하였다. 기도 이물은 24시간이내가 4례(50%)였으며 1례는 18일동안 잔류하였다. 6) 치료에 있어서 식도이물에서 37례(50.7%)는 후두경을 이용한 상부식도경술로, 33례(45.2%)는 국소마취하에 식도경술로, 3례(4.1%)는 전신마취하에 식도경술로 적출하였다. 주화의 경우 총 61례중 8례(13.1%)는 검사도중에 위속으로 내려갔다. 기도이물에서 후두이물 2례는 국소마취하에 후두경으로, 기관이물 5례중 2례(40%)는 국소마취하에 기관절개술과 함께 기관지경술로, 3례(60%)는 전신마취하에 기관지경술로 적출하였으며 기관지이물 1례는 흉부외과에서 전신마취하에 개흉술로 적출하였다.