• 한국연초학회지
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• 제25권2호
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• pp.120-127
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• 2003

Cyclodextrin glucanotransferase (CGTase) from Bacillus stearothermophilus synthesized vanillin and ethyl vanillin monoglucoside, with a series of its maltooligoglucosides by transglycosylation with dextrin as a donor, and vanillin or ethyl vanillin as an acceptor. The monoglucoside formed from reaction mixture of vanillin or ethyl vanillin by the successive actions of CGTase and Rhizopus glucoamylase was isolated by extraction with n-butanol saturated with water and silica gel column chromatography. The structure of the isolated monoglucoside was identified as vanillin- $\alpha$ -D-glucoside and ethyl vanillin- $\alpha$ -D-glucoside, respectively, by FAB-MS, UV, IR, 1H-NMR, 13C-NMR spectra and products by hydrolysis with acid, $\alpha$ - and $\beta$ -glucosidases.

• 한국미생물·생명공학회지
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• 제39권4호
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• pp.374-381
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• 2011

미생물과의 상호작용을 통하여 토양의 특성을 변화시킬 수 있는 지렁이 Eisenia fetida의 장내미생물 군집을 조사하기 위하여, 배양방법과 비배양방법인 DGGE와 pyrosequencing을 이용하여 8주와 16주 사육 지렁이의 장내미생물 군집을 분석하였다. 배양방법에서는 L. fusiformis(51%), B. cereus(30%), E. aerogenes(21%), 그리고 L. sphaericus (15%) 등이 우점미생물로 확인되었다. DGGE 분석에서는 B. cereus(15.1%), Enterobacter sp.(13.6%), uncultured bacterium (13.1%), 그리고 B. stearothermophilus(7.8%)가 우점미생물로 확인되었다. Pyrosequencing 분석에서는 Microbacterium soli(26%), B. cereus(10%), M. esteraromaticum(6%), 그리고 Frigoribacterium sp.(6%)가 우점미생물로 확인되었다. 그외에도 Aeromonas sp., Pseudomonas sp., Borrelia sp., Cellulosimicrobium sp., Klebsiella sp., and Leifsonia sp. 등의 미생물도 확인이 되었으며, 비배양 방법을 이용한 장내 미생물 군집 조사는 배양이 불가능한 미생물을 확인할 수 있을 뿐만 아니라 더 다양한 미생물 군집도 확인할 수 있었다.

• Journal of Microbiology and Biotechnology
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• 제8권4호
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• pp.378-387
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• 1998

The DNA sequence immediately following the xynA gene of Bacillus stearothermophilus 236 ［about l-kb region downstream from the translational termination codon (TAA) of the xynA gene］was found to have an ability to enhance the xylanase activity of the upstream xynA gene. An 849-bp ORF was identified in the downstream region, and the ORF was confirmed to encode a novel protein of 283 amino acids designated as XaiF (xylanase-activity-increasing factor). From the nucleotide sequence of the xaiF gene, the molecular mass and pI of XaiF were deduced to be 32,006 Da and 4.46, respectively. XaiF was overproduced in the E. coli cells from the cloned xaiF gene by using the T7 expression system. The transcriptional initiation site was determined by primer extension analysis and the putative promoter and ribosome binding regions were also identified. Blast search showed that the xaiF and its protein product had no homology with any gene nor any protein reported so far. Also, in B. subtilis, the xaiF trans-activated the xylanase activity at the same rate as in E. coli. In contrast, xaiF had no activating effect on the co-expressed ${\beta}-xylosidase$ of the xylA gene derived from the same strain of B. stearothermophilus. In addition, the intracellular and extracellular fractions from the E. coli cells carrying the plasmid-borne xaiF gene did not increase the isolated xylanase activity, indicating that the protein-protein interaction between XynA and XaiF was not a causative event for the xylanase activating effect of the xaiF gene.

• 한국미생물·생명공학회지
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• 제36권4호
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• pp.360-365
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• 2008

식품 내의 잔류 항생물질의 검사는 주로 미생물의 생육 억제 여부를 통한 생물학적인 분석을 이용한다. 이러한 방법은 여러 가지 계열의 항생제들에 대한 미생물의 민감성을 토대로 이용되고 있다. 그러나 현재 사용하고 있는 미생물들로는 동물용의약품으로 허가되어 식용동물에 사용되고 있는 점점 다양해지는 항생제 및 합성항균제를 식품에서 모두 검출할 수는 없다는 한계가 있다. 그러므로 본 연구는 검출 가능한 항생제 및 합성항균제 계열의 범위를 확대하고, 각 약품별 감도를 증진시키기 위한 새로운 방법들을 조사하였다. B. megaterium ATCC 9885, B. subtilis ATCC 6633, B. cereus ATCC l1778 and Geobacillus stearothermophilus (B. stearothermophilus) ATCC 10149를 사용한 검사의 민감성은 macrolides, quinolones와 monensin, chloramphenicol에 대한 검출 감도가 낮았다. 반면에 M. luteus(K. rhizophila) ATCC 9341는 macrolides에 대한 높은 검출 감도를 나타냈고, E. coli ATCC l1303는 quinolones와 aminoglycosides에 대한 높은 민감성을 나타냈다. 결론적으로, 두 균주의 추가로 검출가능한 항생제 및 합성항균제의 범위를 확대하였으며, 검출감도를 높일 수 있게 되었다.

• 유기물자원화
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• 제1권1호
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• pp.69-84
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• 1993

우분의 효율적인 퇴비화를 위한 최적 공정운용지표를 결정하기 위하여 실험실규모의 퇴비화 반응기를 설치하였다. 우분에 톱밥을 소량 혼합하여 초기의 C/N비를 24, pH를 6.9로 조절하였다. 송기량을 200 ml/min kg. VS, 500 ml/min kg. VS, 1000 ml/min kg. VS, 1500 ml/min kg. VS로 정하여 퇴비화를 실시하고 온도 상승곡선과 최종 C/N비, 분해율로 퇴비화의 효율을 판단한 결과 1000 ml/min kg. VS에서 가장 양호한 퇴비화가 진행되었다. 한편 수분함량을 40%, 50%, 60%, 70%로 달리하여 퇴비화를 실시한 결과 수분함량이 50%일 때 가장 퇴비화의 효율이 좋았으며 20일 후의 분해율은 43%였다. 또한 초기의 pH는 모두 중성내지 약 알카리성으로 상승하였으며 퇴비화의 효율에 있어서는 별다른 차이가 없었다. 즉 온도 상승곡선과 C/N비의 저하, 분해율에 있어서 비슷한 결과를 나타내었다. 상기 실험으로 결정된 최적 운용조건하에서 퇴비화를 실시하여 미생물수를 계수하였다. 세균의 수는 퇴비화의 시간에 따라 증가하여 실험종료일인 20일째는 건조 퇴비화 물질 1g당 $1.5{\times}10^9$세포 였으며 방선균은 $1.1{\times}10^8$개체, 곰팡이는 $3.0{\times}10^8$ 개체였다. 방선균과 곰팡이의 숫자는 다른 연구 결과에서 나타난 수치보다 대체로 높았다. 또한 지표세균군을 계수하였는 바 대장균군은 초기에 건조 퇴비화 물질 1g당 $3.1{\times}10^3$, 분원성 대장균군은 $7.5{\times}10^2$ 세포, 분원성 연쇄상구균은 $5.6{\times}10^5$ 세포 존재하였다. 이러한 개체군수는 퇴비화의 시간이 지남에 따라 감소하여 대장균과 분원성 대장균은 16일째에, 분원성 연쇄상균은 20일째에 발견되지 않았다. 이러한 지표세균군들의 생존기간은 타 연구결과에 비해 대체로 더 길었다. 우분의 퇴비화에서 분리동정된 세균속은 Bacillus 속이 89.3%로 가장 많았으며 Bacillus 속 중에서는 B. circulans complex가 가장 많이 출현하였고 B. stearothermophilus, B. sphericus, B.의 순이었다.

• 유기물자원화
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• 제10권3호
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• pp.126-131
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• 2002

남은 음식물을 기질로 생균사료를 생산하기위하여 고온성 세균에 의한 호기적 액체 발효가 시도되었다. 토양이나 남은 음식물들로부터 11종의 고온성 세균이 $55^{\circ}C$에서의 진탕배양에 의해 분리되었다. 이들 분리균 들의 기질분해능을 평가하기위해 배양액 중에서의 ${\alpha}-amylase$ 와 protease효소역가를 측정 비교하였다. 이 결과 6종의 세균이 선택되었고 남은 음식물 기질 적응력을 높이기 위해 반복 배양을 실시하였다. 발효말기에서의 생균농도는 대부분 $3{\sim}7{\times}10^9/ml$에 이르렀다. 이들 중 B3, B6가 가장 높은 효소역가를 나타냈다. B3, B6, 그리고 분양받은 균주인 Bacillus Stearothermophillus를 2L-jar fermenter를 이용해 혼합발효시킨 결과발효개시 8시간 내에 생균수가 $1.4{\times}10^{10}/ml$에 이르렀다.

• 한국식품영양과학회지
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• 제23권6호
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• pp.964-972
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• 1994

The 4.3-kb gene coding for L-lactate dehydrogenase of Bacillus stearothermophilus has been subcloned and expressed in E. coli cells. The enzyme was purified 200-fold with 25% yield by heat treatment , DEAE-Sephadex, and NAD++ -Sepharose CL-4B affinity chromatography followed by gel filtration through Sephadex G-200 . The molecular weight of the purfied enzyme was estimated to be about 35, 000 and 140, 000 on SDS-polyacrylamide gel electrophoresis and gel filtration, respectively. indicating that the enzyme is composed of four identical subunits. THe enzyme for pyruvate reduction and lactate oxdiation was stable at 60 and 75$^{\circ}C$ for 30 min, and the optimal temperatures for both reactions were 60 and 7$0^{\circ}C$, respectively. The enzyme had an optimal pH at 5.5 and 8.5 in pyruvate reduction and lactate oxidation, respectively. The pH stability of enzyme of pyruvate reduction was table between pH 5 and 7. more than 90% of enzyme activity was lost at 1mM FeSO4 and p-chloromercuribonzoate. The maximal activation of the enzyme was obtained with 0.8mM fructose 1, 6-bisphosphate.

• Journal of Microbiology and Biotechnology
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• 제26권9호
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• pp.1579-1585
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• 2016

Sugar esters are valuable compounds composed of various sugars and fatty acids that can be used as antibacterial agents and emulsifiers in toothpaste and canned foods. For example, fructose fatty acid esters suppress growth of Streptococcus mutans, a typical pathogenic bacterium causing dental caries. In this study, fructose laurate ester was chosen as a target material and was synthesized by a transesterification reaction using Candida antarctica lipase B. We performed a solvent screening experiment and found that a t-butanol/dimethyl sulfoxide mixture was the best solvent to dissolve fructose and methyl laurate. Fructose laurate was synthesized by transesterification of fructose (100 mM) with methyl laurate (30 mM) in t-butanol containing 20% dimethyl sulfoxide. The conversion yield was about 90%, which was calculated based on the quantity of methyl laurate using high-performance liquid chromatography. Fructose monolaurate (M_r 361) was detected in the reaction mixture by high-resolution mass spectrometry. The inhibitory effect of fructose laurate on growth of oral or food spoilage microorganisms, including S. mutans, Bacillus coagulans, and Geobacillus stearothermophilus, was evaluated.

• Journal of Microbiology and Biotechnology
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• 제19권12호
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• pp.1536-1541
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• 2009

The DNA shuffling technique has been used to generate libraries of evolved enzymes in thermostability. We have shuffled two thermostable cytidine deaminases (CDAs) from Bacillus caldolyticus DSM405 (T53) and B. stearothermophilus IFO12550 (T101). The shuffled CDA library (SH1067 and SH1077 from the first round and SH2426 and SH2429 from the second round) showed various patterns in thermostability. The CDAs of SH1067 and SH1077 were more thermostable than that of T53. SH2426 showed 150% increased halftime than that of T53 at $70^{\circ}C$. The CDA of SH2429 showed about 200% decreased thermostability than that of T53 at $70^{\circ}C$. A single amino acid residue replacement that presented between SH1077 and SH2429 contributed to dramatic changes in specific activity and thermostability. On SDS-PAGE, the purified CDA of SH1077 tetramerized, whereas that of SH2429 denatured and became almost monomeric at $80^{\circ}C$. A simulated three-dimensional structure for the mutant CDA was used to interpret the mutational effect.

• Preventive Nutrition and Food Science
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• 제6권4호
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• pp.206-210
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• 2001

Starch is an abundant resource in plant biomass, and it should be hydrolyzed enzymatically into fermentable sugars for ethanol fermentation. A genetic recombinant yeast, Saccharomyces cerevisiae GA-7458, was constructed by integrating the structural gene of both $\alpha$-amylase from Bacillus stearothermophilus and the gene (STA1) encoding glucoamylase from S. diastaticus into the chromosome of S. cerevisiae SH7458. The recombinant yeast showed active enzymatic activities of $\alpha$-amylase and glucoamylase. The productivity of ethanol fermentation from the pH-controlled batch culture (pH 5.5) was 2.6 times greater than that of the pH-uncontrolled batch culture. Moreover, in a fed-batch culture, more ethanol was produced (13.2 g/L), and the production yield was 0.38 with 2% of corn starch. Importantly, the integrated plasmids were fully maintained during ethanol fermentation.