• Microbiology and Biotechnology Letters
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• v.24 no.6
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• pp.726-732
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• 1996

To improve the fermentation characteristics(such as starch-degradability, ethanol tolerance, sugar and high-temperature tolerance) of recombinant haploid yeast Saccharomyces diastaticus K114, hybridization technique was used. The hybridization partner was S. diastaticus 1177 which had good glucoamylase activity and fermentabi- lity. The best hybrid HH64 showed improved ethanol tolerance, sugar and high-temperature tolerance. Especia- lly, the starch-fermentability was significantly improved, since the hybrid produced 1.60% (w/v) ethanol from 4% (w/v) starch, while the recombinant haploid K114 produced 1.30% (w/v) ethanol. The optimum temperature and pH for the starch-fermentation by the hybrid HH64 was 30$\circ$C and 5, respectively. The hybrid yeast HH64 produced 7.5% (w/v) ethanol directly from 20% (w/v) starch.

• Journal of Life Science
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• v.17 no.9 s.89
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• pp.1260-1265
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• 2007

Magnetically separable enzyme-coated nanofibers were developed for the hydrolysis of starch. Stability of ${\alpha}-amylase-coated$ nanofiber was greatly improved and its residual activity was maintained over 92.7% after 32 days incubation at room temperature and under shaking conditions (200 rpm). The recovery of enzyme was high and enzyme activity after 10 recycle was 95.2% of its original activity. Developed enzyme-coated nanofibers were used for the hydrolysis of starch. When 0.5 mg of magnetically separable enzyme nanofibers was used, 40 g/l of starch (2 ml) was completely degraded within 40 min. The continuous enzyme reactor was developed and used for starch hydrolysis and 76% of starch (30 g/l) was hydrolyzed with 1 hr residence time.

• Journal of Microbiology and Biotechnology
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• v.7 no.5
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• pp.310-317
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• 1997

Enzymatic synthesis of glucosyl-sugar alcohols using various transglycosylating enzymes, such as cyclodextrin glucanotransferase (CGTase), ${\alpha}$-amylase, ${\alpha}$-glucosidase, and pullulanase was investigated using various sugar alcohols, such as sorbitol, xylitol, inositol, maltitol, and lactitol as glucosyl acceptors. CGTase showed the highest transglycosylating activity to sugar alcohols compared to other transglycosylating enzymes, and inositol and maltitol were the most suitable glucosyl acceptors. Soluble starch, extruded starch, cyclodextrins, and maltooligosaccharides were also identified to be adequate glucosyl donors for transglycosylation reaction of CGTase to sugar alcohols. The synthesis of glucosyl-maltitol in the reaction system using extruded starch as the glucosyl donor and maltitol as the glucosyl acceptor showed the best results showing the highest transglycosylation yield. The transglycosylation products were purified by activated carbon column chromatography with ethanol gradient elution. Chemical structures of above transglucosylated products were analyzed by nuclear magnetic resonance spectroscopy, and two products were identified to be maltotritol and maltotetraitol, in which one or two glucose molecules attached to the parent maltitol molecule by a ${\alpha}$-l,4-glucosidic bond, respectively.

• Microbiology and Biotechnology Letters
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• v.26 no.2
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• pp.143-150
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• 1998

Many enzymes catalyze a primary reaction and/or secondary reaction. Dextransucrase usually synthesize dextran from sucrose as a primary reaction. The secondary reaction of dextransucrase is the transfer of glucose from sucrose to carbohydrate accepters. We have reacted dextransucrase from Leuconostoc mesenteroides B-742CB with sucrose and starches; granule or gelatinized starches, and Small or Potato starches. The yield of modified starch was ranged from 46% to 72%(s.d.<${pm}$5%) of theoretical depends on various reaction conditions. Modified products were more resistant against the hydrolysis of ${alpha}$-amylase, isoamylase, pullulanase and endo-dextranase than those of native starch. Based on the reactions from enzyme hydrolysis and methylation followed by acid hydrolysis modification of granule starch was more efficient than the modification of gelatinized starch. After modification of granule starch with dextransucrase, there produced a soluble modified starch. After modification the starch granules were fractionated to small size. The positions of glucose substitution of the modified products were determined by methylation followed by acid hydrolysis and analyzed by TLC. The products were modified by the addition of glucose to the position of C3, C4 and C6 free hydroxyl group of glucose residues in the starch.

• Journal of Microbiology and Biotechnology
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• v.3 no.2
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• pp.99-107
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• 1993

Two strains (No. 26 and 143) of bacteria which secrete both pectinase and raw-starch-digesting amylase simultaneously, were isolated from various domestic soil samples. The two bacteria were identified as Pasteurella ureae judging by their morphological and physiological characteristics. The optimal culture conditions for the production of raw-starch-digesting enzyme by the Pasteurella ureae 26 were using $NH_4NO_3$ as the nitrogen source at $37^{\circ}C$ with the pH of 7.5, and 15 of C/N ratio. Since the enzyme was produced only when raw or soluble starch was used as a carbon source, but not when glucose or other sugars was used, the enzyme was considered to be an inducible enzyme by starch. Thin layer chromatography of the hydrolyzed product of starch by the raw-starch-digesting enzyme of the strain No. 26 showed that glucose, maltose and other oligosaccharides were present in the hydrolyzates, and therefore the enzyme seemed to be ${\alpha}-amylase$. The enzyme had adsorbability onto raw com starch in the pH range of 3 to 9.

• The Korean Journal of Mycology
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• v.17 no.3
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• pp.149-153
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• 1989

One strain of Aspergillus niger K-25 producing an acid-stable ${\alpha}-amylase$ was isolated from the soil. The optimum culture conditions were investigated. The production of the acid-stable ${\alpha}-amylase$ was enhanced when the strain was incubated in a medium containing soluble starch 3.5%, peptone 2%, $KH_2PO_4$ 0.5%, $MaSO_4{\cdot}7H_2O$ 0.25% and $FeCI_3$ 1.0% at pH 3 for 7 days. However, higher activity of acid-stable ${\alpha}-amylase$ was demonstrated on wheat bran culture. Amylase production was doubled when A. niger K-25 was incubated on the wheat bran supplemented with fumaric acid buffer (pH 3).

• Journal of the Korean Wood Science and Technology
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• v.42 no.2
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• pp.149-156
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• 2014

Termites are wood pests that cause vast economic damage every year. They digest both cellulose and starch, but the enzymes for starch digestion have not been well characterized. We obtained complete amino acid sequence information on the KME1 ${\alpha}$-amylase from Reticulitermes speratus KMT1 through analysis of total mRNA sequences. The KME1 enzyme has two ${\alpha}$-amylase domains and is 68% identical to the ${\alpha}$-amylase from Blattellager manica, its closest relative in the GenBank database. Some unique features of its conserved region and its distant evolutionary relationship to other insect ${\alpha}$-amylases suggest that KME1 is a new type of ${\alpha}$-amylase.

• Korean Journal of Microbiology
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• v.36 no.2
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• pp.112-118
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• 2000

A new gene encoding an acidophilic TEX>$\alpha$-amylase of Bacillus cil-culans KCTC3004 was cloned into Eschericlzia coli using pUC19 as a vector. The gene localized in the 5.8 kb PstI DNA fragment was expressed independently of its orientation in the cloning vector showing enzyme activity about 40 times greater than that produced by the original B, circulans The optimum pH and temperature of the cloned enzyme were pH 3.6 and 45^{\circ}C.$ respectively. The enzyme hydrolyzed starch to produce maltotriose and maltooligosaccharides. The SDS-PAGE and zymopram of the enzyme produced in E coli(p.4L850) indicated a molecular weight of 55,000.

• The Korean Journal of Food And Nutrition
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• v.10 no.4
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• pp.480-484
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• 1997

Sugars in Korean ginseng(Panax ginseng C. A. Meyer) were studied by HPLC, TLC and NMR. The sugars in Korean ginseng were crushed and extracted by boiling for 30min. Korean ginseng was found to contain 3.77% of sucrose, 3.50% of maltose, 0.09% of fructose and 0.04% of glucose and 3.90% of starch. No other mono- and oligosaccharides were detected in the test of TLC and HPLC. Starch in ginseng showed only signal of $\alpha$-1, 4-glucosidic linkage by proton NMR analysis, and showed 92% of absorbance by iodine reaction compared with amylose(DP 117). These results indicated that starch in Korean ginseng is composed by only amylose. Pectin content in ginseng showed 0.22% as galcturonic acid by carbazole analysis.

• Microbiology and Biotechnology Letters
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• v.42 no.4
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• pp.407-412
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• 2014

A number of Saccharomycopsis fibuligera strains that can hydrolyse and utilize starch as a carbon source were isolated from nuruk, a traditional Korean starter for rice wine fermentation, and their specific growth rates on starch-containing medium were compared to choose the prominent strain. S. fibuligera strain MBY1320 showed a higher growth rate at $42^{\circ}C$ than that of strain S. fibuligera KCTC7806, indicating that S. fibuligera MBY1320 has more thermo-tolerant machinery for starch hydrolysis and utilization than KCTC7806. Although the activity of ${\alpha}$-amylase at $30^{\circ}C$ was significantly lower for S. fibuligera MBY1320 than KCTC7806 (3,812.5 U vs. 14,878.5 U), S. fibuligera MBY1320 showed a much higher glucoamylase activity at $42^{\circ}C$ than S. fibuligera KCTC7806 (5,048.9 U vs. 13,152.3 U). Thus, a new S. fibuligera strain, with a higher starch-hydrolysing activity at elevated temperatures than that of other types of strain, this study reports.