• Microbiology and Biotechnology Letters
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• v.16 no.6
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• pp.494-498
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• 1988

The optimum conditions for glucoamylase production, and ethanol productivity of the transformant TSD-14 were investigated as compared with the parental strains. The properties of TSD-14 were comparatively similar to the donor S. diastaticus IFO 1046 as regards the conditions of glucoamylase production and ethanol productivity. The soluble starch was the most effective carbon source for the glucoamylase production. While inorganic nitrogen sources did not prompt cell growth and enzyme production, the organic nitrogen sources generally enhanced both cell growth and glucoamylase production. The metal salts such as FeSO$_4$, MgSO$_4$, MnCl$_2$, and NiSO$_4$were favorable to the enzyme production. And the optium temperature and initial pH for glucoamylase production were 3$0^{\circ}C$ and 5. The transformant TSD-14 produced 8.3%(v/v) ethanol from 15% sucrose medium, 4.8%(v/v) ethanol from 15% soluble starch medium, and 7.5%(v/v) ethanol from 15% liquefied potato starch medium. The corresponding fermentation efficiency were 84% , 45% and 70%, respectively.

• Journal of Microbiology and Biotechnology
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• v.4 no.3
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• pp.230-232
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• 1994

The enzymes $\alpha$-amylase and glucoamylase used in starch hydrolysis were found active in the supercritical carbon dioxide solvent Higher hydrolysis of starch sluny in supercritical $CO_2$ was achieved by operating the reactor for the first two hours with $\alpha$ -amylase and to subsequent addition of glucoamylase for continued hydrolysis.

• Microbiology and Biotechnology Letters
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• v.16 no.4
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• pp.320-326
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• 1988

Glucoamylase (EC 3.2.1.3) of Aspergillus sp. isolated from soil was partially purified by Sephacryl S-200 gel filtration and DEAE-Sephacel ion exchange chromatography, The glucoamylase activity was separated into two isozymes after DEAE-Sephacel ion exchange chromatrography. The optimum pH and temperature for both glucoamylase isozymes (GI, GII) were identical; pH 4.5 and temperature, $65^{\circ}C$. The molecular weights of GI and GII Isozymes were estimated to be 105,000, which were measured by gel filtration on Sephacryl S-200. Both isozymes were stable at pH ranges of 2 to 7, and up to 6$0^{\circ}C$. Glycerol was effective to stabilize the both isozymes. The activation energies of GI and GII isozymes were 10.63 and 10.33 kcal/mole, respectively. The enzyme activities of both isozymes were completely inactivated by addition of 0.1% Hg$^{++}$. In kinetic studies, the Km values of GI isozyme for soluble starch, dextrin, and glycogen were 0.62%, 0.32%, and 1.02%, respectively. For GII isozyme, they became 0.66%, 0.23%. and 0.14% for the substrates.

• Microbiology and Biotechnology Letters
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• v.18 no.4
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• pp.352-359
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• 1990

The synergistic effect of glucoamylase and a -amylase on the hydrolysis of raw corn starch in an agitated bead reaction system was studied by investigating the changes of sugar profiles, the granular structure, particle size distribution, and X-ray diffraction pattern of residual raw corn starch. The enzymatic hydrolysis of raw corn starch was greatly enhanced by synergistic effect of glucoamylase and $\alpha$ -amylase. Even though the sugar profiles were mainly determined by the mixing ratio of glucoamylase and $\alpha$-amylase; raw starch was mainly converted to glucose directly without accumulation of any significant amount of oligosaccharides. The cavity formation and fragmentation phenomena of raw corn starch granule subjected to enzyme reaction were analyzed by means of SEM and the particle size distribution. The X-ray diffraction pattern of raw starch was not changed at the initial stage of reaction but slightly changed at the late stage of hydrolysis, which may be caused by the preferential degradation of amorphous region by enzymatic reaction, not by the destruction of microcrystalline structure of raw corn starch.

• Microbiology and Biotechnology Letters
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• v.16 no.6
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• pp.489-493
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• 1988

To obtain a new yeast strain that is able to efficiently produce ethanol from starch, the glucoamylase gene of Saccharomyces diastaticus was transformed into S. cerevisiae without a cloning vector. The competent cells of S. cerevisiae, induced by the treatment of Li$_2$SO$_4$, were transformed with the partial BamHI-digests of chromosomal DNA of S. diastaticus, and the transformants were selected by their abilities to utilize and ferment starch. The transformants, which appeared at a frequency of 8.5$\times$10$^{-7}$, were able to withstand up to 800 ppm of copper sulfate like the recipient and retained the phenotypic expression of the recipient with the exception of the acquisition of STA gene and MAL gene, as regards fermentation of carbohydrates. The enzymatic properties of glucoamylases produced by transformants were very similar to those produced by S. diastaticus as based on optimium pH and temperature.

• Journal of the Korean Society of Food Science and Nutrition
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• v.14 no.2
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• pp.188-191
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• 1985

A thermophilic and cellulolytic bacterium, Herpetosiphon geysericola CUM 317 isolated from the compost, produced ${\alpha}-amylase,\;{\beta}-amylase$, and glucoamylase. Mutual relationships on the production of the three amylases were studied by changing the cultivation conditions. ${\alpha}-Amylase$ and glucoamylase were produced highly after 40 hrs on wheat bran medium at $50^{\circ}C$ and after 30 hrs on liquid medium at $40^{\circ}C$, though ${\beta}-amylase$ was produced best at 10 hrs of initial cultivation phase. The production of the amylases was generally repressed by the addition of carbon sources in liquid medium containing polypeptone. ${\alpha}-Amylase$ production was enhanced relatively by the addition of cupric sulfate in the liquid medium, ${\beta}-amylase$ was enhanced by cadmium sulfate, and glucoamylase was enhanced by calcium chloride.

• Korean Journal of Microbiology
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• v.18 no.4
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• pp.161-171
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• 1980

A mutant strain having increased productivity of both enzymes, protease and amylase, was obtained from A. flavus KU 153, isolatd from South Korea for its high protease production by successive ultra-violet light irradiation, Two glucoamylases from the mutant strain selected were purified from wheat branculture by successive salting out, followed by dialysis and column chromatography, and their characteristics were compared with those of the wild strain. Glucoamylase production of the mutant selected was increased about 3.3 times compared with the wild strain, and 2.1 times compared with the parental strain, ${\alpha}-amylase$ activity of the mutant selected was about 2 times hugher than that of the wild strain or the parental strain. Protease and cellulase productivities of the muant selected were all alike compared with those of the highly proteolytic mutant, the parental strain. Therefore, it was considered that the back mutation on the protease production did not occurred in the formation process of the glucoamylase producing mutant. Total activities of glucoamylase I and II from the mutant selected were 2.86 and 3.65 times higher compared with those from the wild strain, respectively. Considering the optimal pH-thermal stability and Km-Vmax value of glucoamylase I and II from both strains, wild and mutant, it was deduced that the characteristics of glucoamylase I and II from the wild strain did not altered during the mutation process. Therefore, it was concluded that the selected mutant did not induce the formation of another glucoamylase isozyme, or the changes in the characteristics of the glucoamylase, but induce the productivity of the same glucoamylase I and II by the action of regulatory gene.

• Journal of environmental and Sanitary engineering
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• v.5 no.1
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• pp.49-64
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• 1990

Glucoamylase from the culture filtrate of Aspergillus nicer was purified by ammonium sulfate precipitation, aceton precipitation, DEAE-cellulose ion exchange chromatography and Sephadex G-50 gel fillration. Glucoamylase was secreted into the medium upon growth on glucose, sucrose or a variety of other hexose sugars or hexose sugar polymers and little or no glucoamylase activity was found when glycerol or xylose was used as the carbon source. The optimum pH and temperature (or the maximum enzyme activity were found to be 5.0 and $50^{\circ}C$, respectively. The enzyme was considerably thermostable, for no loss of activity was observed when the enzyme was preincubated at $60^{\circ}C$ for 30 min. The enzyme activity was inhibited by 20 mM of $Hg^{2+}$, $Fe^{2+}$. The km value for starch was 0.045%.

• Microbiology and Biotechnology Letters
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• v.17 no.5
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• pp.519-523
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• 1989

The effects of carbon, nitrogen sources and culture conditions on glucoamylase production from Aspergillus sp. were investigated. Among tested carbon sources, soluble starch was most effective for the production of the enzyme, and the level of concentration for the optimal enzyme production was found to be 5%. For nitrogen sources, yeast extract was best for the enzyme production, with the level of 0.1%. The enzyme was maximally produced by cultivating the organism at medium of initial pH 6.0, and temperature of 28$^{\circ}C$. Wheat bran was most suitable for the enzyme production from the organism in solid state culture.

• Journal of Microbiology and Biotechnology
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• v.24 no.12
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• pp.1690-1698
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• 2014

Partial purification of glucoamylase from solid-state fermentation culture was, firstly, investigated by reverse micellar extraction (RME). To avoid back extraction problems, the glucoamylase was kept in the original aqueous phase, while the other undesired proteins/enzymes were moved to the reverse micellar organic phase. The individual and interaction effects of main factors (i.e., pH and NaCl concentration in the aqueous phase, and concentration of sodium bis-2-ethyl-hexyl-sulfosuccinate (AOT) in the organic phase) were studied using response surface methodology. The optimum conditions for the maximum recovery of the enzyme were pH 2.75, 100 mM NaCl, and 200 mM AOT. Furthermore, the optimum organic to aqueous volume ratio ($V_{org}/V_{aq}$) and appropriate number of sequential extraction stages were 2 and 3, respectively. Finally, 60% of the undesired enzymes including proteases and xylanases were removed from the aqueous phase, while 140% of glucoamylase activity was recovered in the aqueous phase and the purification factor of glucoamylase was found to be 3.0-fold.