• 한국축산식품학회지
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• 제33권4호
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• pp.439-447
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• 2013

Time-temperature integrators (TTIs) are simple and cost-efficient tools which may be used to predict food quality. Enzymatic TTIs are devised to indicate food quality in the form of color alterations from green to red, based on the cumulative impacts of temperature and time period on the enzymatic reactions. In this study, the quality of ground beef patties was investigated for the parameters of pH levels, color, VBN, water holding capacity, and total microbial counts, depending on various storage temperatures (5, 15, and $25^{\circ}C$). TTIs were attached to the surface of the ground beef patties in order to evaluate the degree of correlating colorimetric changes with the determined quality parameters. Through the Arrhenius equation, activation energy and constant reaction rates of TTI, VBN, and total microbial counts were calculated as to observe the relationship between enzymatic reactions of the TTI and food spoilage reactions of the ground beef patties. VBN and total microbial counts were already increased to reach decomposition index (VBN: 20, total microbial count: 7-8 Log CFU/g) of meat at middle stage of storage period for each storage temperature. Although activation energy of TTI enzymatic reactions and food spoilage reactions of the ground beef patties were similar, the change of TTI color was not a coincidence for food spoilage at $5^{\circ}C$ and $15^{\circ}C$ of storage temperature. It was suggested that TTI should be designed individually for storage temperature, time, type of meat, or decomposition index of meat.

• Bulletin of the Korean Chemical Society
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• 제27권2호
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• pp.281-285
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• 2006

Microbial fuel cells (MFC) stacked with bipolar plates have been constructed and their performance was tested. In this design, single fuel cell unit was connected in series by bipolar plates where an anode and a cathode were made in one graphite block. Two types of bipolar plate stacked MFCs were constructed. Both utilized the same glucose oxidation reaction catalyzed by Gram negative bacteria, Proteus vulgaris as a biocatalyst in an anodic compartment, but two different cathodic reactions were employed: One with ferricyanide reduction and the other with oxygen reduction reactions. In both cases, the total voltage was the mathematical sum of individual fuel cells and no degradation in performance was found. Electricity from these MFCs was stored in a supercapacitor to drive external loads such as a motor and electric bulb.

• Asian-Australasian Journal of Animal Sciences
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• 제21권1호
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• pp.144-154
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• 2008

The rumen microbial ecosystem produces methane as a result of anaerobic fermentation. Methanogenesis in the rumen is thought to represent a 2-12% loss of energy intake and is estimated to be about 15% of total atmospheric methane emissions. While methanogenesis in the rumen is conducted by methanogens, PCR-based techniques have recently detected many uncultured methanogens which have a broader phylogenetic range than cultured strains isolated from the rumen. Strategies for reduction of methane emissions from the rumen have been proposed. These include 1) control of components in feed, 2) application of feed additives and 3) biological control of rumen fermentation. In any case, although it could be possible that repression of hydrogen-producing reactions leads to abatement of methane production, repression of hydrogen-producing reactions means repression of the activity of rumen fermentation and leads to restrained digestibility of carbohydrates and suppression of microbial growth. Thus, in order to reduce the flow of hydrogen into methane production, hydrogen should be diverted into propionate production via lactate or fumarate.

• Journal of Microbiology and Biotechnology
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• 제20권4호
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• pp.809-816
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• 2010

Microbial biotransformations can be used to predict mammalian drug metabolism. The present investigation deals with microbial biotransformation of valdecoxib using microbial cultures. Thirty-nine bacterial, fungal, and yeast cultures were used to elucidate the biotransformation pathway of valdecoxib. A number of microorganisms metabolized valdecoxib to various levels to yield nine metabolites, which were identified by HPLC-DAD and LC-MS-MS analyses. HPLC analysis of biotransformed products indicated that a majority of the metabolites are more polar than the substrate valdecoxib. Basing on LC-MS-MS analysis, the major metabolite was identified as a hydroxymethyl metabolite of valdecoxib, whereas the remaining metabolites were produced by carboxylation, demethylation, ring hydroxylation, N-acetylation, or a combination of these reactions. The hydroxymethyl and carboxylic acid metabolites were known to be produced in metabolism by mammals. From the results, it can be concluded that microbial cultures, particularly fungi, can be used to predict mammalian drug metabolism.

• 환경위생공학
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• 제11권2호
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• pp.27-31
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• 1996

2,4,6-Trinitrotoluene(TNT) was reduced into intermediate products by mixed culture incubated in anaerobic condition. To test the effects of extracellular material to electron transfer between sulfide and TNT, filtered medium of mixed culture was loaded in the test tubes with TNT and sulfide. The transformation rate was measured under four different conditions. The rate under microbial activity was the fastest among under different conditions. With sulfide or filtrate alone and TNT, the reactions were measured as the slowest reactions or no reactions occured, respectively. The reaction rate coefficient were calculated by linear regression and the first order kinetic was fitted best. Also, the plot of rate coefficients (K$_{f}$) showed linear relationships when at time zero TNT and sulfide concentration were 20 mg/1 and 6.0 mM, respectively. By extrapolation, reaction rate coefficient of 100% filtrate could be calculated as 0.0054/minute. However, reaction rate was affected by different concentration of sulfide, so it is a dependent of sulfide concentration. The results of this test showed TNT reduction rate can be limited more by microbial reaction than by mediation of filtrate or sulfide and filtrate alone.

• Bulletin of the Korean Chemical Society
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• 제24권4호
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• pp.437-440
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• 2003

In a mediator-aided microbial fuel cell, the choice of a proper mediator is one of the most important factors for the development of a better fuel cell system as it transfers electrons from bacteria to the electrode. The electrochemical behaviors within the lipid layer of two representative mediators, thionin and safranine O both of which exhibit reversible electron transfer reactions, were compared with the fuel cell efficiency. Thionin was found to be much more effective than safranine O though it has lower negative formal potential. Cyclic voltammetric and fluorescence spectroscopic analyses indicated that both mediators easily penetrated the lipid layer to pick up the electrons produced inside bacteria. While thionin could pass through the lipid layer, the gradual accumulation of safranine O was observed within the layer. This restricted dynamic behavior of safranine O led to the poor fuel cell operation despite its good negative formal potential.

• 한국습지학회지
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• 제11권1호
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• pp.123-130
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• 2009

지표수-지하수 혼합대는 지표수와 지하수의 수리적 교환이 일어나는 하상의 간극수 지역으로 모든 자연하천에 존재한다. 이 지역은 그동안 다른 특성으로 분리되었던 지표수와 지하수의 전이대로 다양한 미생물이 서식하고 있으며, 하변과는 또 다른 생지화학적인 기작이 일어날 것으로 추정된다. 지금까지의 연구는 미미하지만, 지표수-지하수 혼합대를 고려한 하천 생태 연구는 하천 전체의 생지화학적 기작을 이해하는데 중요한 역할을 할 것으로 보인다. 본 연구 대상 지역은 내성천(경상북도 예천군 고평교 하류 구간)으로 이 하천은 사질 하상이며, 자연이 그대로 보존되어있다고 평가 받는 자연 직할 하천이다. 토양시료는 하변 달뿌리풀(Phragmites japonica) 식생지, 나지, 수변 혼합대와 사주 혼합대 하강류(downwelling), 상승류(upwelling) 지역에서 깊이 별로 채취하여 수분함량, pH 및 용존유기탄소와 같은 토양 이화학적인 분석과 체외 미생물 효소($\beta$-glucosidase, N-acetylglucosaminidase, phosphatase and arylsulfatase) 활성도, 미생물 군집구조(eubacteria, denitrifying bacteria)의 특성을 알아보았다. 실험 결과 수변 및 사주 지표수-지하수 혼합대 토양이 많은 수분을 함유하고 있었고, 수분함량과 용존 유기탄소는 양의 상관관계를 보였으며, 체외 미생물 효소 활성도는 용존유기탄소와 양의 상관관계를 보였다. 진정세균 군집구조 또한 수변 및 사주의 지표수-지하수 혼합대에서 독특한 경향을 보였다. 이와 같은 결과는 지표수-지하수 혼합대를 통해 일어나는 하천의 생지화학적인 순환 전체를 이해하기 위한 기반을 제공한다.

• 한국환경과학회지
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• 제23권10호
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• pp.1745-1753
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• 2014

Sediment microbial fuel cell (SMFC), equipped with Zn, Al, Cu, Fe or graphite felt (GF) anode and marine sediment, was performed. Graphite felt was used as a common cathode. SMFC was single chambered and did not use any redox mediator. The aim of this work was to find efficient anodic material. Oxidation reduction potential (ORP), cell voltage, current density, power density, pH and chemical oxygen demand (COD) were measured for SMFC's performance.. The order of maximum power density was $913mWm^{-2}$ for Zn, $646mWm^{-2}$ for Fe, $387.8mWm^{-2}$ for Cu, $266mWm^{-2}$ for Al, and $127mWm^{-2}$ for graphite felt (GF). The current density over voltage was found to be strongly correlated with metal electrodes, but the graphite felt electrode, in which relatively weaker electricity was observed because of its bio-oriented mechanism. Metal corrosion reactions and/or a complicated microbial electron transfer mechanism acting around the anodic compartment may facilitate to generate electricity. We presume that more sophisticated selection of anodic material can lead to better performance in SMFC.

• 약학회지
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• 제16권3호
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• pp.137-147
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• 1972

Estrone, which is obtainable from 19-hydroxycholesterol acetate through microbial oxidation, was chemically transformed to orally active estrogens, ethynylestradiol and methylestradiol. For progestin synthesis, $5{\alpha}$-bromo-619-oxidoisoandrosterone, was harvested from the culture broth(ATCC:19170), in which $5{\alpha}$-bromo-619-oxidocholestanol, acetate was added as a carbon source. Methylestrenolone, a potent orally active progestin, was synthesized from the harvested product via several reactions. Norethindrone, a popular progestin, was also prepared from 19-norandrostenedione. 19-Norandrostenedione is also available through microbial oxidation and chemical modification of $5{\alpha}$-chlor-619-oxidocholestanol, acetate.

• Archives of Pharmacal Research
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• 제2권2호
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• pp.153-157
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• 1979

The carpophores of three Korean mushrooms, Coriolus versicolor, Pleurotus ostreatus, and Lentinus edodes were respectively extracted with hot water and the extract were dialyzed through Visking tube. They were found to contain an antinumor activity against sarcoma 180 implanted in mice. The components of these aqueous extracts were found to be polysaccharide and protein by color reactions including anthrone and Lowry-Folin tests. The hydrolysis of the polysaccharide with 3% HCI-MeOH and trimethylsilylation yielded four monosaccharides : glucose, mannose, galactose and xylose which were identified by G. L. C. After hydrolysis of protein with 6N HCL, fourteen to seventeen amino acids including aspartic and glutamic acids were detected by an amino acid analyzer.