• Journal of Environmental Health Sciences
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• v.23 no.4
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• pp.21-25
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• 1997

A study on the removal of mercury by Saccharomyces cerevisiae and Aureobasidium pullulans was done, in which the model of adsorption isotherm and adsorption rate was proposed. The adsorption isotherm of mercury by S. cerevisiae was accorded with Langmuir model but A. pullulans was followed to Freundlich model. The amount of mercury removed by A. pullulans was higher than that of S. cerevisiae, but the adsorption rate of mercury by A. pullulans was slower than that of S. cerevisiae. In a rapid adsorption process, therefore, it is more useful to use S. cerevisiae as a biosobent.

• The Korean Journal of Food And Nutrition
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• v.7 no.4
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• pp.259-266
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• 1994

The hyperthermophilic archaebacterium Thermococcus profundus Isolated from a deep-sea hydrothermal vent system, produced several amylolytic enzymes such as extracellular amylase and pullulanase, intracellular a-1,4-91ucosidase in respone to the presence of complex carbohydrates In the growth medium. This strain showed high activities on 0.5% maltose than on complex carbohydrates One of the amylases was partially purified by ammonium sulfate precipitation, DEAE-Toyopearl chromatography. The amylase exhibited maximal activity at pH 5.5 and 80$^{\circ}C$, and was stable in the range of pH 5.5 to 9.5 and up to 80$^{\circ}C$ for 30 min. The enzyme activity was no dependence on Ca2+ and not inhibited by detergents. The amylase hydrolyzed soluble starch, amylose, amylopectin and glycogen to produce maltose and maltotriose with trace amounts of glucose, but not pullulan and ${\alpha}$-, ${\beta}$-, ${\gamma}$-cyclodextrin. Malto-oligosaccharides ranging from maltotetraose to maltoheptaose were hydrolyzed in an endo fashion.

• Proceedings of the Microbiological Society of Korea Conference
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• 1991.04a
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• pp.225-236
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• 1991

The genes encoding the thermostable $\alpha$-amylase and maltogenic amylase from Bacillus lichenciformis were cloned and expressed in E. coli. The recombinant plasmid pTA322 was found to contain a 3.1kb EcoRI genomic DNA fragment of the thermostable $\alpha$-amylase. The cloned $\alpha$-amylase was compared with the B. licheniformis native $\alpha$-amylase. Both $\alpha$-amylase have the same optimal temperature of $70^{\circ}C$ and are stable in the pH range of 6 and 9. The complete nucleotide sequences of the thermostable $\alpha$-amylase gene were determined. It was composed of one open reading rame of 1,536 bp. Start and stop codons are ATG and TAG. From the amino acid sequence deduced from the nucleotide sequence, the cloned thermostable $\alpha$-amylase is composed of 483 amino acid residues and its molecular weight is 55,200 daltons. The content of guanine and cytosine is $47.46mol\%$ and that of third base codon was $53_41mol\%$. The recombinant plasmid, pIJ322 encoding the maltogenic amylase contains a 3.5kb EcoRI-BamHI genomic DNA fragment. The optimal reaction temperature and pH of the maltogenci amylase were $50^{\circ}C$ and 7, respectively. The maltogenic amylase was capable of hydrolysing pullulan, starch and cyclodextrin to produce maltose from starch and panose from pullulan. The maltogenic amylase also showed the transferring activity. The maltogenic amylase gene is composed of one open reading frame of 1,734bp. Start and stop codons are ATG and ATG. At 2bp upstream from start codon, the nucleotide sequence AAAGGGGGAA seems to be the ribosome-binding site(RBS, Shine-Dalgarno sequence). A putative promoter(-35 and-10 regions) was found to be GTTAACA and TGATAAT. From deduced amino acid sequence from the nucleotide srquence, this enzyme was comosed of 578 amino acid residues and its molecular weight was 77,233 daltons. The content of guanine and cytosine was $48.1mol\%$. The new recombinant plasmid, pTMA322 constructed by inserting the thermostable $\alpha$-amylase gene in the EcoRI site of pIJ322 to produce both the thermostable $\alpha$-amylase and the maltogenic amylase were expressed in the E. coli. The two enzymes expressed from E. coli containing pTMA322 was reacted with the $15\%$ starch slurry at $40^{\circ}C$ for 24hours. The distribution of the branched oligosaccharides produced by the single-step process was of the ratio 50 : 50 between small oligosaccharide up DP3 and large oligosaccharide above DP3.

• Food Science and Preservation
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• v.11 no.4
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• pp.496-502
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• 2004

Purified acorn starch was obtained from alkali precipitation method. Acorn amylose and acorn amylopectin were fractionated from purified acorn starch by butanol improvement method. Gel permeation chromatography (GPC) was used to measure molecular weight distribution of acorn starch, acorn amylose, acorn amylopectin and corn starch, corn amylose, corn amylopectin. GPC measurement diagrams were obtained by each retention time. And then, we used DMSO and DMF as solvent, pullulan as standard material. We calculated the Number-average molar mass (Mn), Weight-average molar mass (Mw) and polydispersity from molecular weight distribution of each sample. As a result of estimating molecular weight using GPC, Mw of amylose has small value than Mw of amylopectin. From this fact, the molecular structural aspects of amylose and amylopectin were predicted and it was in good agrement with the tendency of polydispersity by GPC. The polydispersity of starch had big value than amylose and amylopectin, from this result, it might be known that the range of molecular weight appeared broad by heterogeneous properties of two components. The viscosity of purified acorn starch, amylose, amylopectin seperated from acorn starch, was decreased by increasing the shear rate and raising the temperature exponentially. Acorn starch solutions exhibited pseudoplastic power law fluid behavior.

• Korean Journal of Microbiology
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• v.29 no.2
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• pp.104-110
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• 1991

The glucoamylase of Schwanniomyces castellii was purified to homogeneity from the culture filtrate. the purified enzyme was a glycoprotein with a molecular mass of about 145 KDa, which was monomeric protein with an isoelectric point of 4.3. The pH and temperature optima were 5.5 and 40.deg.C, respectively. The enzyme was fairly stable up to 50.deg.C and at acid pH range (pH 4.5-6.0). The apparent Km of the enzyme toward soluble starch, isomaltose and pullulan were 3.84, 0.51 and 13.7 mg/ml, respectively. The analysis of amino acid composition on this enzyme was found to be acidic protein like other fungal glucoamylase. The amino acid sequence of N-terminal peptide consisted of Ala-Pro-Ala-Asp-Gly-Ile-Gly-Asp-X-Ala-X-Ala.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.510-510
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• 2013

탄소나노튜브를 발광층에 첨가하여 Alternating current (AC) 방식으로 구동되는 고분자유기물 소자를 제작하였다. 고분자유기물 소자는 ITO가 코팅된 유리기판을 사용하였으며, 전극으로는 ITO와Al을 사용하고 cyanoethyl pullulan (CRS)의 유전물질과 탄소나노튜브를 함유한 poly[2-methoxy-z5-(2-ethyl-hexyloxy)-1,4-phenylene-vinylene](MEH-PPV) 고분자유기발광물질을 이용하여 4개의 층(ITO/CRS/탄소나노튜브를 함유한 MEH-PPV/Al)으로 고분자유기물 소자를 구성하였다. 소자는 ITO가 코팅된 유리 기판 위에 CRS의 유전층과 탄소나노튜브를 함유한 MEH-PPV의 발광층은 스핀코우터를 이용하여 증착하였으며, Al은 thermal evaporator을 이용하여 증착하였다. 본 연구에서는 AC 방식 고분자유기물 소자에 탄소나노튜브의 함유량을 변경하면서 전압과 전류 특성을 관찰하여 탄소나노튜브가 함유된 소자가 저 전류 구동이 가능한 것을 확인하였으며, 탄소나노튜브를 통한 micro-capacitance 효과의 확인 및 percolation과의 상관관계를 알아보았다. AC 고분자유기물 소자는 가정에서 사용되는 AC전원을 바로 사용할 수 있는 범용성을 가지고 있으며, 탄소나노튜브를 발광층에 첨가함으로 낮은 소비전력으로 고분자유기물 소자를 구동 할 수 있는 장점으로 차세대 디스플레이나 조명으로 그 쓰임새를 기대해본다.

• Journal of Microbiology and Biotechnology
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• v.4 no.1
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• pp.41-48
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• 1994

The xylanase from alkali-tolerant Bacillus sp. YA-14 was purified to homogeneity by CM-cellulose, Sephadex G-50, and hydroxyapatite column chromatographies. The molecular weight of the purified enzyme was estimated to be 20, 000 Da by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The purified enzyme slightly hydrolyzed carboxymethyl cellulose and Avicel, but did not hydrolyze soluble starch, dextran, pullulan, and ${\rho}-nitrophenyl-{\beta}$-D-xylopyranoside. The maximum degree of hydrolysis by enzyme for birchwood xylan and oat spelts xylan were 47 and 40%, respectively. The Michaelis constants for birchwood xylan and oat spelts xylan were calculated to be 3.03 mg/ml and 5.0 mg/ml, respectively. The activity of the xylanase was inhibited reversibly by $HgCl_2$, and showed competitive inhibition by N-bromosuccinimide, which probably indicates the involvement of tryptophan residue in the active center of the enzyme. The Xylanase was identified to be xylose-producing endo-type xylanase and did not show the enzymatic activities which cleave the branch point of the xylan structure.

• Microbiology and Biotechnology Letters
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• v.25 no.2
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• pp.109-114
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• 1997

The Oomycete Saprolegnia ferax produces an extracellular $\beta$-amylase, Maximum enzyme yield was attained after 7 days of growth in YNB starch medium (pH 6.5) at 25$\circ$C. The amylase was pu- rified 24-fold by ultrafitration, HPLC DEAE column and HPLC gel filtration. The purfied enzyme was a monomeric glycoprotein with a molecular weight of about 44,000 dalton. The pH and temperature optima were 6.5 and 50$\circ$C, respectively. The enzyme was fairly stable up to 50$\circ$C and at acidic pH region (pH 4.0-7.0). The apparent Km and Vmax values of the enzyme against soluble starch were 0.77 mg/ml and 2,174 $\mu$moles/mg protein, respectively. Amino acid analysis indicated that the enzyme was enriched in alanine, glycine, leucine and acidic amino acid. Starch hydrolysis with the enzyme released maltose but not glucose, whereas maltotriose, Schardinger dextrin ($\alpha$-cyclodextrin) and pullulan were not hydrolysed by the enzyme. The enzyme was inhibited by Schardinger dextrin, p-chloromercuribenzoate(PCMB), CU$^{2+}$' and Hg$^{2+}$. Inhibition of the enzyme by PCMB could be reversed by the addition of cysteine and mercaptoethanol.

• Korean Journal of Microbiology
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• v.30 no.6
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• pp.519-523
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• 1992

The glucoamylase of Candida tsuubaensis was purified to homogeneity form culture filtrate by means of ultrafiltration, Sephacryl S-200 gel filtration and Sp-Sephadex C-50 chromatography. The purified enzyme was a glycoprotein with a molecular mass of approximately 50 kDa, which was a monomeric protein. Km values were 5.8 mg/ml for soluble starch and 0.04 mM for maltose. Glucoamylase also released only glucose from both pullulan and isomaltose. The analysis of amino acid composition revealed that the enzyme contained a high content of acidic and polar amino acids. In addition, Western blotting analysis indicates that C. tsukubaensis glucoamylase is resistant to glucose repression.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.342-345
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• 2000

Effect of volcanic ash on cell growth of Aspergillus sp. and production of exopolymers by Agrobacterium sp. and Aureobasidium pullualns was investigated. The volcanic ash contained various mineral salts such as $SiO_2$, $Al_2O_3$, CaO, $K_2O$. Maximal cell growth of Aspergillus sp. was obtained when 0.3% volcanic ash was added to medium. Cell growth of Aspergillus sp. increased with higher concentration of volcanic ash in medium. Amount of cell growth with 0.3 % volcanic ash was 6.7 times higher than that without volcanic ash. Volcanic ash also stimulated production of exopolymer as well as cell growth. Production of curdlan with 0.1% volcanic ash was 12.40 g/l whereas that without volcanic ash was 9.15 g/l. Production of pullulan with volcanic ash was also higher than that without volcanic ash.