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

• Korean Journal of Food Science and Technology
• /
• v.18 no.1
• /
• pp.24-30
• /
• 1986

The model foods similar to general Korean foods were prepared by combining starch, protein and moisture, and relationship between their thermal diffusivities and components were investigated. Thermal diffusivity of the model foods tended to be proportional with the moisture content. Under the same level of moisture content of the model foods, thermal diffusivity of the starch foods was higher than that of the protein foods, but no interaction among components was found. The measured values was quite agreed upon with the calculated values with 3.60 residual percent. The regression equations between thermal diffusivity and moisture, protein and starch contents at $20^{\circ}C$ and $60^{\circ}C$ were ${\alpha}20^{\circ}C$ = 0.04911M+0.37355P+3.73072, ${\alpha}60^{\circ}C$ = 0.05353M-0.4766P+4.15136, respectively. The correlation coefficients obtained according to the above equation were $0.9650^{**}$ and $20^{\circ}C$ and $0.9002^{**}$ at $60^{\circ}C$.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.21 no.1
• /
• pp.23-28
• /
• 1992

Starch solid model system was employed to investigate the effect of lipoxygenase, ${\beta}-carotene$, ${\alpha}-tocopherol$ and water activity on the oxidation of linoleic acid. The rate of oxidation of linoleic acid by lipoxygenase was increased with the increase in water activity, Addition of ${\beta}-carotene$ and ${\alpha}-tocopherol$ to this system has been shown to inhibit the oxidation of linoleic acid and ${\alpha}-tocopherol$ was more effective antioxidant than ${\beta}-carotene$. However, an increase in the concentration of ${\beta}-carotene$ was found to have a strong antioxidant effect in the solid model system. And also the antioxidative action of ${\beta}-carotene$ was increased with increasing water activity in this system.

• Microbiology and Biotechnology Letters
• /
• v.17 no.1
• /
• pp.1-7
• /
• 1989

To enhance the capability of starch fermentation of the transformant TSD-14, the heat treated protoplasts of TSD-14 were fused with the protoplasts of C. tropicalis (lys$^-$) in the presence of 30% (w/ v) PEG and 20 mM CaC1$_2$. Fusants were selected by nutritional complementation on minium medium and the fusion frequency was 4.4$\times$10$^{-5}$. All fusants tested were possessed of complemented traits concerning carbon compound assimilation, and the cell volumes of the fusants were approximately 1.5 times larger than the parental strains. The fusants were genetically very stable, and were able to hydrolyze alpha 1,4-glucosidic linkage as well as alpha 1,6-linkage of starch contrary to one of parents TSD-14, The most promising fusant FSC-14-75 produced 8.7% (v/v) of ethanol from 15% liquefied potato starch medium, but the result was enhanced to 9.3% (v/v) by addition of 0.3% peptone. The corresponding fermentation efficiency was 86.0%.

• Microbiology and Biotechnology Letters
• /
• v.21 no.6
• /
• pp.582-587
• /
• 1993

The extracellular alpha-amylase was purified to homogenity from the culture filtrate of starch grown Sch. castellii CBS 2863. The purified enzyme was glycoprotein with a molecular weight of about 56 kDa. The pH and temperature optimum were 5.5 and 40C, respectively. The enzyme was fairly stable up to 40C and at acid pH range (pH 4.0-7.0). The apparent Km and Vmax of the enzyme toward starch was 1.0mg/ml and 100U/mg protein, respectively. The analysis of amino acid composition was found to be acidic protein. The amino acid sequence of N-terminal peptide consisted of Asp-Val-Ser-Ser-Ala-X-X-Thr-Arg-Ser-Glu-Ser-Ile-Tyr.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.29 no.1
• /
• pp.49-56
• /
• 2000

The 2-O-$\alpha$-D-glucopyranosyl L-ascorbic acid (AA-2G) which was enzymatically glucosylated with the cyclodextrin glucanotransferase (CGTase) [EC 2.4.1.19] from Bacillus sp. JK-43 has been reported previously. The presnet experiments examined the optimal conditons for the productio of AA-2G from AA and soluble starch, and characterized the properties of the CGTase from Bacillus sp. JK-43. The reaction mixture for the maximal production of AA-2G was followings; 12% total substrate concentration, 1,400 usits/mL of CGTase and a mixing ratio of 2 : 3(g or AA : g of soluble starch). Under this condition, 1.76mM of AA-2G, which corresponded to 2.53% yield based on AA, was produced after incubation for 24hrs at 45$^{\circ}C$ (pH 5.5). The optimum pH and temperature for the CGTase activity were 6.0 and 45$^{\circ}C$, respectively. The enzyme was stable at pH 5.5 to 9.5, and at temperature up to 5$0^{\circ}C$. The thermostability of the enzyme could be enhanced up to 6$0^{\circ}C$ by the addition of 30mM CaCl2.

• Journal of Microbiology and Biotechnology
• /
• v.20 no.2
• /
• pp.383-390
• /
• 2010

A newly isolated active producer of raw-starch-digesting amyloytic enzymes, Rhizopus microsporus var. chinensis CICIM-CU F0088, was screened and identified by morphological characteristics and molecular phylogenetic analyses. This fungus was isolated from the soil of Chinese glue pudding mill, and produced high levels of amylolytic activity under solid-state fermentation with supplementation of starch and wheat bran. Results of thin-layer chromatography showed there are two kinds of amyloytic enzymes formed by this strain, including one $\alpha$-amylase and two glucoamylases. It was found in the electron microscope experiments that the two glucoamylases can digest raw corn starch and have an optimal temperature of $70^{\circ}C$. These results signified that amyloytic enzymes secreted by strain Rhizopus microsporus var. chinensis CICIM-CU F0088 were types of thermostable amyloytic enzymes and able to digest raw corn starch.

• Archives of Pharmacal Research
• /
• v.29 no.12
• /
• pp.1179-1186
• /
• 2006

Cross-linked starch microspheres were prepared using different kinds of cross-linking agents. The influence of several parameters on morphology, size, swelling ratio and drug release rate from these microspheres were evaluated. These parameters included cross-linker type, concentration and the duration of cross-linking reaction. Microspheres cross-linked with glutaraldehyde had smooth surface compared with those prepared with epichlorhydrine or formaldehyde. The particle size increased with increasing the cross-linking time and increasing the drug loading. Swelling ratio of the particles was a function of cross-linker type but not the concentration or time of cross-linking. Drug release from starch microspheres was measured in phosphate buffer and also in phosphate buffer containing a-amylase. Results showed that microspheres cross-linked with epichlorhydrine released all their drug content in the first 30 minutes. However, cross-linking of the starch microspheres with glutaraldehyde or formaldehyde decreased drug release rate. SEM and drug release studies showed that cross-linked starch microspheres were susceptible to the enzymatic degradation under the influence of alpha-amylase. Changing the enzyme concentration from 5000 to 10,000 IU/L, increased drug release rate but higher concentration of enzyme (20,000 IU/L) caused no more acceleration.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.45 no.6
• /
• pp.78-87
• /
• 2013

Even though the notice No. 2010-11 of the Ministry of Food and Drug Safety Administration that has been applied to analyze the content of the water soluble residue eluted from multi-layer paperboard was abolished in 2011, its application for the analysis on evaporation residue is still valid. There are very high possibilities that the noticed existing method gives the misleading result on the evaporation residue due to the water soluble starch eluted from the multi-layer paperboard. The quantitative analysis on water-soluble residue with starch content correction has been carried in the study using UV/Vis spectroscopy and HPLC. The UV/Vis spectroscopy absorbance analysis showed the large amount of the oxidized starch obtained from the aqueous residue eluted out of the multi-layer paperboard after the iodine, ${\alpha}$-amylase reaction, and starch hydrolysis. The residual content decreased by the correction through the enzyme hydrolysis.

• The Korean Journal of Food And Nutrition
• /
• v.18 no.1
• /
• pp.4-10
• /
• 2005

Periodate-oxidized soluble starch increased pH stability of Aspergillus awamori a-glucosidase. After incubation for two hours, the enzyme in the absence of oxidized soluble starch was stable in the range of pH 3-7 at 40℃, pH 3-6 at 50℃ and the enzyme in the presence of oxidized soluble starch was stable in the range of pH 3-9 at 40℃, pH 3-8 at 50℃. At 60℃, the enzyme was stable in pH 3-6 regardless of the presence or absence of IO₄-oxidized soluble starch, but when IO₄-oxidized soluble starch existed in pH 5-6, remained activity of the enzyme increased 20% more than when it didn't exist. The enzyme modified with IO₄-oxidized soluble starch remained 70% of activity in pH 9, but native enzyme didn't remain, showing the increase of stability due to modification. In thermal stability, modified enzyme remained 12% at 50℃ and 7% at 80℃. But native enzyme remained 8% at 50℃ and didn't remain at more than 70℃. The result of HPLC analysis revealed the subunit of the enzyme at under pH 2 or over pH 9 was separated or the enzyme was denatured and conjugated. Protein structure of native enzyme was denatured by acidic and basic pH but was stable in the presence of IO₄-oxidized soluble starch.