• Microbiology and Biotechnology Letters
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• v.23 no.5
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• pp.573-579
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• 1995

A Bacillus strain capable of producing an extracellular malto-oligosaccharides forming $\alpha $-amylase was isolated from soil and designated as Bacillus sp. SUH4-2. The enzyme was purified by ammonium sulfate fractionation, DEAE-Toyopearl and Mono-Q HR 5/5 column chromatographies using a FPLC system. The specific activity of the enzyme was increased by 16.1-fold and the yield was 13.5%. The optimum temperature for the activity of $\alpha $-amylase was 60-65$\circ$C and more than 50% of initial activity was retained after the enzyme was incubated at 60$\circ$C for 40 min. The enzyme was stable over a broad pH range of 5.0-8.0 and the optimum pH was 5.0-6.0. The molecular weight of the enzyme was determined to be about 63.6 kD and isoelectric point was around 5.8. The enzyme activity was strongly inhibited by Mn$^{2+}$, Ni$^{2+}$, and Cu$^{2+}$ ; slightly by Ca$^{2+}$. The purified enzyme produced starch hydrolyzates containing mainly maltose and maltotriose from soluble starch. The starch hydrolyzates were composed of 11% glucose, 59% maltose, 25% maltotriose and 5% maltotetraose.

• 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.

• Microbiology and Biotechnology Letters
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• v.19 no.2
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• pp.163-170
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• 1991

Production of cyclodextrin (CD) directly from raw corn starch without liquefaction using cyclodextrin glucanotransferase (CGTase) was carried out in an agitated bead reaction system. Similar CD yield and production rate comparable with those of conventional method using liquefied starch were obtained. Especially high purity-CD in the reaction mixture without accumulation of malto-oligosaccharides was obtained. The maximum 54g/l of CD was obtained at raw starch concentration of 200g/l. CD yield was inversely proportional to raw starch concentration, and conversion yield was 0.48 at substrate concentration of 100g/l. The optimal amount of enzyme (CGTase unit/g raw starch) was found to be around 6.0. Granular structure of raw starch degraded by CGTase was observed by SEM in order to investigate the enhancing mechanism, along with those of acid or alkali pretreated raw starch, amylose, and amylopectin. Kinetic constants of CGTase on raw starch in an agitated bead reaction system were evaluated, and CGTase was competitively inhibited by CD.

• Microbiology and Biotechnology Letters
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• v.19 no.5
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• pp.514-520
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• 1991

Direct synthesis of cyclodextrin (CD) from extruded insoluble corn starch without liquefaction procedure using cyclodextrin glucanotransferase (CGTase) was carried out. Increased CD production rate and yield were achieved in heterogeneous enzyme reaction system containing extruded corn starch compared with those of conventional system employing liquefied or partially cyclized starch. At extruded starch concentration of 100 g/l the CD concentration and conversion yield were reached up to 54 g/l and 0.54, respectively. High purity of $\alpha \beta \gamma$-CDs without accumulation of undesirable malto-oligosaccharides was produced, furthermore, the residual extruded starch was easily separated by centrifugation from reaction mixture, whlch will facilitate the purification procedure. Granular structure of extruded starch was observed by SEM to investigate enzyme reaction mechanism. Supplemental addition of $\alpha$-amylase enhanced slightly the initial CD production rate, but it decomposed produced CD at the late stage. Various! extruded raw starches, such as, corn, rice, and barley were also suitable substrates for CD production.

• Food Science and Preservation
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• v.15 no.3
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• pp.477-482
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• 2008

The quality characteristics of Goami by-product under the mixed enzyme treatment condition of $\alpha$-amylase and cellulase have been compared, and found the highest amount of soluble solids and reducing sugars at the $\alpha$-amylase treated group (A), and the contents revealed to show gradual decrease with the increase of cellulase content. The amounts of total dietary fiber and total sugars did not show large difference by both of enzyme concentration. The result of sugar analysis revealed the presence of all $G{\sim}G5$ in all treatment groups, and the content of malto-oligosaccharide recorded the highest content of 2,200 mg% at the $\alpha$-amylase treatment group (A). When the quality characteristic of the hydrolyzed powders manufactured by the optimum hydrolysis condition was compared, no significant color difference was found between samples. Among the contents of dietary fibers, insoluble dietary fiber was found to present in the lowest content of 6.95% at the Goami flour (GF) and the Goami by-product powder (GBPP) and Goami by-product hydrolysate powder (GBPHP) resulted the similar content around 14% and the highest soluble dietary fibers content was found in Goami by-product hydrolysate powder (GBPHP), which was followed by in the order of Goami by-product powder (GBPP) and Goami flour (GF), but the content variation was not large. The free amino acid was found to be highest in Goami by-product hydrolysate powder (GBPHP) followed by in the order of Goami by-product powder (GBPP) and Goami flour (GF). In the sugar analysis, the Goami by-product hydrolysate powder (GBPHP) was found with all $G{\sim}G5$ sugars by showing the highest amount of 1,800 mg% At the Goami by-product powder (GBPP), $G{\sim}G2$ sugars were detected with about 66 mg% and malto-oligosaccharides were not detected at the Goami flour (GF). Based upon the results, the functionality of Goami by-product hydrolysate powder (GBPHP) was found to be enforced compared to Goami flour (GF) and Goami by-product powder (GBPP), which allow us to expect it to be used as the various rice processing food source.