• Journal of Microbiology and Biotechnology
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• 제3권2호
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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.

• KSBB Journal
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• 제13권5호
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• pp.621-625
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• 1998

The raw starch hydrolysis by amylase prepared from alkaline-tolerant Bacillus sp. were investigated. Degree of hydrolysis(%) of 5%(w/v) raw rice, corn and potato starch by this enzyme were about 40, 25 and 20%, respectively. The hydrolysis action on raw starch by change of blue value was similar to the action pattern of exo ${\beta}$-amylase. The hydrolysis products of rice starch were mainly glucose and maltose. Oligosaccarides were also detected. From the above results, this enzyme was considered as exo type ${\alpha}$-amylase. This enzyme activity on the raw starch and the gelatinized starch were 28.40 and 86.60 IU/mg protein, respectively, and the ratio of raw starch-digesting activity to gelatinized starch-digesting activity (raw starch digestivity) was about 32%. The Km values for the raw and the gelatinized starch were 4.22 and 3.0mg/mL, respectively, and the VmaX values were 0.20 and 0.31mg/mL/min, respectively.

• 한국식품과학회지
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• 제27권5호
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• pp.773-775
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• 1995

The effect of alum$(Al{\cdot}K(SO_4)_2{\cdot}12H_{2}O)$ on the activity of raw starch-digesting enzyme produced by alkali-tolerant Bacillus sp. was investigated. In adding alum of 0.5%(w/w), activities of raw starch-digesting enzyme on the gelatinized and raw rice starches have not been inhibited. In case of adding alum of 5%(w/w), competitive and uncompetitive inhibition were observed for the gelatinized and raw rice starches, respectively. The inhibitory effect on the raw starch was much higher than that on the gelatinized starch.

• Journal of Microbiology and Biotechnology
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• 제20권4호
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• pp.718-726
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• 2010

A selected fungal strain, for production of the raw-starchdigesting enzyme by solid-state fermentation, was improved by two repeated sequential exposures to ${\gamma}$-irradiation of $Co^{60}$, ultraviolet, and four repeated treatments with Nmethyl-N'-nitrosoguanidine. The mutant strain Aspergillus sp. XN15 was chosen after a rigorous screening process, with its production of the raw-starch-digesting enzyme being twice that of usual wild varieties cultured under preoptimized conditions and in an unsupplemented medium. After 17 successive subculturings, the enzyme production of the mutant was stable. Optimal conditions for the production of the enzyme by solid-state fermentation, using wheat bran as the substrate, were accomplished for the mutant Aspergillus sp. XN15. With the optimal fermentation conditions, and a solid medium supplemented with nitrogen sources of 1% urea and 1% $NH_4NO_3$, 2.5 mM $CoSO_4$, 0.05% (v/w) Tween 80, and 1% glucose, the mutant Aspergillus sp. XN15 produced the raw-starch-digesting enzyme in quantities 19.4 times greater than a typical wild variety. Finally, XN15, through simultaneous saccharification and fermentation of a raw rice corn starch slurry, produced a high level of ethanol with $Y_{p/s}$ of 0.47 g/g.

• Journal of Microbiology and Biotechnology
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• 제20권2호
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• pp.383-390
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• 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.

• Journal of Microbiology and Biotechnology
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• 제2권1호
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• pp.56-65
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• 1992

The complete nucleotide sequence of the Bacillus circulans F-2 RSDA gene, coding for raw starch digesting a-amylase (RSDA), has been determined. The RSDA structure gene consists of an open reading frame of 2508 bp. Six bp upstream of the translational start codon of the RSDA is a typical gram-positive Shine-Dalgarno sequence and the RSDA encodes a preprotein of 836 amino acids with an Mr of 96, 727. The gene was expressed from its own regulatory region in E. coli and two putative consensus promoter sequences were identified upstream of a ribosome binding site and an ATG start codon. Confirmation of the nucleotide sequence was obtained and the signal peptide cleavage site was identified by comparing the predicted amino acid sequence with that derived by N-terminal analysis of the purified RSDA. The deduced N-terminal region of the RSDA conforms to the general pattern for the signal peptides of secreted prokaryotic proteins. The complete amino acid sequence was deduced and homology with other enzymes was compared. The results suggested that the Thr-Ser-rich hinge region and the non-catalytic domain are necessary for efficient adsorption onto raw substrates, and the catalytic domain (60 kDa) is necessary for the hydrolysis of substrates, as suggested in previous studies (8, 9).

• Journal of Microbiology and Biotechnology
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• 제19권10호
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• pp.1161-1168
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• 2009

Ethanol production by the simultaneous saccharification and fermentation (SSF) of low-value rice wine cake (RWC) without cooking was investigated. RWC is the filtered solid waste of fermented rice wine mash and contains 53% raw starch. For the SSF, the RWC slurry was mixed with the raw-starch-digesting enzyme of Rhizopus sp. and yeast, where the yeast strain was selected from 300 strains and identified as Saccharomyces cerevisiae KV25. The highest efficiency (94%) of ethanol production was achieved when the uncooked RWC slurry contained 23.03% starch. The optimal SSF conditions were determined as 1.125 units of the raw-starch-digesting enzyme per gram of RWC, a fermentation temperature of $30^{\circ}C$, slurry pH of 4.5, 36-h-old seeding culture, initial yeast cell number of $2{\times}10^7$ per ml of slurry, 17 mM of urea as the nitrogen additive, 0.25 mM of $Cu^{2+}$ as the metal ion additive, and a fermentation time of 90 h. Under these optimal conditions, the ethanol production resulting from the SSF of the uncooked RWC slurry was improved to 16.8% (v/v) from 15.1% (v/v) of pre-optimization.

• 한국미생물·생명공학회지
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• 제17권2호
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• pp.136-141
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• 1989

Streptomyces sp. 4M-2의 생전분 분해효소를 황산 암모니움 염석과 이온교환 크로마토그라피 및 Gel 여과 등으로 비활성이 51.22 RSU/mg, 수율 4.5%로 정제할 수 있었다. 정제효소의 분자량은 102,000이었으며 생옥수수 전분에 대한 Km값은 44.44mg/m1 이었다 정제효소의 작용 최적온도는42$^{\circ}C$, pH는 5.5였고 $Ca^{2+}$와 $Ba^{2+}$의 첨가에 의해 효소활성이 증가되었다. 정제효소는 옥수수 amylose를 가장 잘 분해하고 감자전분도 비교적 잘 분해하였다. 이 효소에 의한 옥수수 생전분의 분해산물은 주로 maltose와 maltotriose였고 소량의 glucose와 oligosaccharide도 검출되었으므로 $\alpha$-amylase 계통의 효소로 추정된다.

• 한국미생물·생명공학회지
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• 제16권6호
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• pp.457-462
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• 1988

방사균이 생산하는 생전분 분해효소를 식품공업에 이용하기 위한 자료를 얻고자 메주로부터 생전분 분해력이 강한 방사균을 분리하여 Streptomyces sp.로 동정하였다. 밀기울침출액 기본배지에 4%의 호화옥수수전분과 0.16%의 KNO$_3$를 첨가하고 pH를 6.2 로 조정한 다음 분리균주를 접종한 후 3$0^{\circ}C$에서 5~6일간 진탕배양하였을 때 33RSU/$m\ell$의 생전분 분해효소를 생산하였다. 또한 효소생산에 효과적인 금속 이온은 인정되지 않았으며 Hg$^{2+}$ 및 Co$^{2+}$ 등은 저해가 현저하였다.

• 한국식품과학회지
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• 제18권4호
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• pp.288-293
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• 1986

유안염석과 column chromatography 및 gel여과 등으로 비활성이 45.2U/mg가 되는 정제된 Rhizopus oryzae의 생전분 분해효소를 16.2%의 수율로 얻었다. 정제효소는 전기영동상에서 그 순도가 인정되었고 분자량은 67000, Km값은 4.082mg/ml이었다. 정제효소는 $50^{\circ}C$, pH $4.0{\sim}5.0$에서 잘 작용하였으며 옥수수amylose가 가장 적합한 전분이었고 옥수수 생전분에 작용한 분해산물은 거의 glucose였다.