• 한국응용과학기술학회지
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• 제26권1호
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• pp.10-17
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• 2009

This study investigated the effect of kilning condfition on the diastatic power and activities of protease, $\alpha$-amylase, and $\beta$-amylase in rice malt. Common rice (Oryza sativa) was steeped at $30^{\circ}C$ for 50 h, germinated at $30^{\circ}C$ for 7 days, and kilned at $50^{\circ}C$ for 24 h. The moisture content and enzymatic activities were determined under various kilning times. As a result, the moisture content was reduced from 42.1 % to 3.9% after 24 h of kilning at $50^{\circ}C$. The protease activity of rice malt showed lower value than that of barley malt. All enzymatic activities were decreased during the kilning stage. Results indicated that after prolonged kilning at $50^{\circ}C$, the inactivation of hydrolytic enzymes might be occurred. Even though the amylolytic activity of malted rice showed low value, the rice malt shows the potential characteristics as ingredient for the brewing and cereal industries.

• Journal of Microbiology and Biotechnology
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• 제8권6호
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• pp.625-630
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• 1998

Using a modified yeast secretory expression vector, $\alpha$-amylase of Schwanniomyces occidentalis was produced from Saccharomyces cerevisiae. The expression vector contains the a-amylase gene (AMY) harboring its own promoter without the regulatory region and the adenine base at the -3 position from the ATG start codon, its own signal sequence, CYC1 transcription terminator, and SV40 enhancer. The expressed $\alpha$-amylase activity from cells carrying the plasmid was approximately 26 times higher than that from the cells harboring an unmodified plasmid. When Saccharomyces diastaticus was transformed with this modified vector, a 2.5 times higher level of amylolytic activity than that from Sch. occidentalis was observed.

• 한국미생물·생명공학회지
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• 제27권6호
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• pp.509-514
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• 1999

Forty seven amylolytic Bifidobacterium strains were isolated on starch-containing agar medium from the faecal samples of the various age groups of Korean. From these amyloytic Bifidobacterium spp., two strains of KFRI 1535, identified temporarily as Bifidobacterium longum, and KFRI 1550, identified as Bifidobacterium breve, showed great macrophage-stimulating activity for the production of tumor necrosis factor-$\alpha$ and inteleukin-6. As the cell concentration increased the cytokine production increased, although in some strains the cytokine levels started to decline over cell concentration increased the cytokine production increased, although in some strains the cytokine levels started to decline over cell concentration of $250\mu\textrm{g}$/ml. the strains which showed high cytokine-stimulating activity generally showed greater production of nitric oxide even though differences were less between strains. Selected Bifidobacterium strains were compared for their fermentation capability in saccharified rice solution and in apple pomace mixture.

• 동아시아식생활학회지
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• 제23권6호
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• pp.833-838
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• 2013

양조용 곰팡이 12균주에 대하여 WEB(wheat extract broth), PDB(potato dextrose broth), MEB(malt extract broth) 배지에서의 배양특성 및 전분분해 효소 활성을 조사하였다. PDB 배지에서의 균체 생산량은 1.26(R. oryzae KACC 45741)~4.80(A. oryzae KACC 46959) g/100 mL로 WEB, MEB 배지보다 각각 2.3~9.2배, 1.7~14.6배 낮았다. A. oryzae의 경우, 상업유통 균주인 Suwon, CF1001, CF1003 균주들이 야생 균주인 KACC 46421, KACC 46423, KACC 46424, KACC 46959보다 건조 균체량이 높았다. Rhizopus sp.의 산 생성량은 WEB, PDB, MEB 배지에서 각각 0.12~0.47, 0.22~1.0, 0.16~0.68%(as lactic acid)이었으며, A. oryzae는 0.06~0.11, 0.03~0.04, 0.06~0.08%(as citric acid) 범위이었다. 전분분해효소 활성은 Rhizopus sp.의 경우, R. delemer KACC 46419 균주만 WEB와 MEB에서 각각 0.013 U, 0.019 U의 활성을 보인 반면, A. oryzae의 효소 활성은 WEB, PDB, MEB 배지에서 각각 0.019~0.037, 0.017~0.033, 0.028~0.046 U 범위였다. 결론적으로 액체 종국용 배지는 균체 생산성이 비교적 우수하였고, 효소활성이 높았던 MEB 배지를 사용하는 것이 유리한 것으로 생각된다.

• Journal of Microbiology and Biotechnology
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• 제31권2호
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• pp.272-279
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• 2021

Two genes encoding probable α-ʟ-arabinofuranosidase (E.C. 3.2.1.55) isozymes (ABFs) with 92.3% amino acid sequence identity, ABF51A and ABF51B, were found from chromosomes 3 and 5 of Saccharomycopsis fibuligera KJJ81, an amylolytic yeast isolated from Korean wheat-based nuruk, respectively. Each open reading frame consists of 1,551 nucleotides and encodes a protein of 517 amino acids with the molecular mass of approximately 59 kDa. These isozymes share approximately 49% amino acid sequence identity with eukaryotic ABFs from filamentous fungi. The corresponding genes were cloned, functionally expressed, and purified from Escherichia coli. SfABF51A and SfABF51B showed the highest activities on p-nitrophenyl arabinofuranoside at 40~45℃ and pH 7.0 in sodium phosphate buffer and at 50℃ and pH 6.0 in sodium acetate buffer, respectively. These exoacting enzymes belonging to the glycoside hydrolase (GH) family 51 could hydrolyze arabinoxylo-oligosaccharides (AXOS) and arabino-oligosaccharides (AOS) to produce only ʟ-arabinose, whereas they could hardly degrade any polymeric substrates including arabinans and arabinoxylans. The detailed product analyses revealed that both SfABF51 isozymes can catalyze the versatile hydrolysis of α-(1,2)- and α-(1,3)-ʟ-arabinofuranosidic linkages of AXOS, and α-(1,2)-, α-(1,3)-, and α-(1,5)-linkages of linear and branched AOS. On the contrary, they have much lower activity against the α-(1,2)- and α-(1,3)-double-substituted substrates than the single-substituted ones. These hydrolases could potentially play important roles in the degradation and utilization of hemicellulosic biomass by S. fibuligera.

• Journal of Microbiology and Biotechnology
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• 제20권9호
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• pp.1307-1313
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• 2010

An extracellular ${\alpha}$-amylase from Lactococcus lactis IBB500 was purified and characterized. The optimum conditions for the enzyme activity were a pH of 4.5, temperature of $35^{\circ}C$, and enzyme molecular mass of 121 kDa. The genome analysis and a plasmid curing experiment indicated that $amy^+$ genes were located in a plasmid of 30 kb. An analysis of the phylogenetic relationships strongly supported a hypothesis of horizontal gene transfer. A strong homology was found for the peptides with the sequence of ${\alpha}$-amylases from Ralstonia pikettii and Ralstonia solanacearum. The protein with ${\alpha}$-amylase activity purified in this study is the first one described for the Lactococcus lactis species, and this paper is the first report on a Lactococcus lactis strain belonging to the amylolytic lactic acid bacteria (ALAB).

• 한국작물학회지
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• 제43권1호
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• pp.19-22
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• 1998

Effects of acute anoxia on carbohydrate hydrolytic enzyme activities and free amino acid contents in malt were examined. Malts were prepared with barley grains germinated for 7 days which contained the highest levels of amylolytic and(1-3,1-4)-$\beta$-glucanase activities. $\alpha$-Amylase and $\beta$-amylase activities in malts were not significantly affected by anoxia for 5 or 10 h.(1-3,1-4)-$\beta$-Glucanase activity, however, decreased about 7 to 10% by anoxia for 5 or 10 h. Alanine and $\gamma$-aminobutyric acid content changed drastically. Alanine contents in malts increased by 2.2- and 2-fold, and $\gamma$-aminobutyric acid contents by 1.4- and 1.9-fold under anoxia for 5 and 10 h, respectively.

• 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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• 제18권3호
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• pp.457-464
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• 2008

An extracellular enzyme (RMEBE) possessing ${\alpha}-(1{\rightarrow}4)-(1{\rightarrow}6)$-transferring activity was purified to homogeneity from Rhodothermus marin us by combination of ammonium sulfate precipitation, Q-Sepharose ion-exchange, and Superdex-200 gel filtration chromatographies, and preparative native polyacrylamide gel electrophoresis. The purified enzyme had an optimum pH of 6.0 and was highly thermostable with a maximal activity at $80^{\circ}C$. Its half-life was determined to be 73.7 and 16.7 min at 80 and $85^{\circ}C$, respectively. The enzyme was also halophilic and highly halotolerant up to about 2M NaCl, with a maximal activity at 0.5M. The substrate specificity of RMEBE suggested that it possesses partial characteristics of both glucan branching enzyme and neopullulanase. RMEBE clearly produced branched glucans from amylose, with partial ${\alpha}-(1{\rightarrow}4)$-hydrolysis of amylose and starch. At the same time, it hydrolyzed pullulan partly to panose, and exhibited ${\alpha}-(1{\rightarrow}4)-(1{\rightarrow}6)$-transferase activity for small maltooligosaccharides, producing disproportionated ${\alpha}-(1{\rightarrow}6)$-branched maltooligosaccharides. The enzyme preferred maltopentaose and maltohexaose to smaller maltooligosaccharides for production of longer branched products. Thus, the results suggest that RMEBE might be applied for production of branched oligosaccharides from small maltodextrins at high temperature or even at high salinity.

• 한국미생물·생명공학회지
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• 제44권4호
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• pp.488-492
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• 2016

S. fibuligera 균주는 생전분을 분해하는 활성이 있는 효모 균주이다. 본 연구에서는 첨가되는 젖산의 농도가 점차 증가하는 장기간 반복 회분식 배양 방법을 사용하는 적응진화를 통하여 S. fibuligera 균주의 젖산에 대한 내성을 증진시키고자 하였다. 진화된 균주인 S. fibuligera MBY1940 균주는 비성장속도 측정과 평판배지를 사용하는 성장분석을 통하여 모균주가 성장할 수 없는 젖산 농도 2.5%에 대해서도 내성을 나타내는 것을 확인하였다. 전자현미경 관찰을 통하여 젖산이 첨가된 스트레스 조건에서 모균주는 신장된 세포 형태와 세포막에 손상을 입은 것으로 보아 진화된 균주에 비해 젖산에 대하여 상대적으로 취약한 것으로 판단되었다.