• Microbiology and Biotechnology Letters
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• v.20 no.6
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• pp.707-710
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• 1992

Bacillus stearothermophilus No.239 isolated from soil was mutated with N-methyl-N'nitro-N-nitrosoguanidine (MNNG) to yield a series of mutants with increasing levels of cyclomalto-dextrin glucanotransferase (EC 2.4.1.19` CGTase) production. After five consecutive mautation steps, a mutant MNNG 8 with about 14 times of CGTase activity than the parent strain was obtained.

• Journal of Food Hygiene and Safety
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• v.38 no.5
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• pp.356-360
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• 2023

We analyzed the heat resistance of non-pathogenic Bacillus atrophaeus, Bacillus subtilis, and Geobacillus stearothermophilus spores which exhibit strong heat resistance and evaluated the possibility of using them to determine direct sterilization when manufacturing retort foods. The D₁₂₁-values of B. subtilis, G. stearothermophilus, and B. atrophaeus spores were 2.9±0.1 min, 4.3±0.1 min, and 3.7±0.1 min, respectively. The Z-values of B. subtilis, G. stearothermophilus, and B. atrophaeus spores were 43.0±1.4℃, 25.0±1.6℃, and 35.8±1.4℃, respectively. The D₁₂₁-values of B. subtilis, G. stearothermophilus, and B. atrophaeus spores were all higher than that of Clostridium botulinum spores used to confirm retort food sterilization. Considering these results, B. subtilis, G. stearothermophilus, and B. atrophaeus spores can be used instead of the pathogenic spore-forming bacteria C. botulinum when sterilizing retort food. In addition, sterilization can be confirmed in 2 to 3 days, a shorter time than the 13 days required for existing bacterial growth experiments based on the Korean food code.

• Research in Plant Disease
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• v.8 no.4
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• pp.234-238
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• 2002

In vitro and in vivo activities of a biocontrol agent, Bacillus stearothermophilus strain YC4194 was evaluated for the control of Pythium damping-off of cucumber. B. stearothermophilus YC4194 inhibited germination of cystospores and formation of zoosporangia of Pythium aphanidermatum in vitro. Incorporation of a bentonite and talc based formulation(10$^{9}$ cfu/g) of B. stearothermophilus YC4194 to the nursery soils (10 g/ι soil) resulted In a significant (p=0.01) reduction in the disease severity of cucumber damping-off after inoculation with P. aphanidermatum. The control efficacy of B. stearothermophilus YC4194 formulation was not different from that of the fungicides, dimethomorph, metalaxyl, ethaboxam. When the cucumber plants were transplanted to the soil inoculated with P. aphanidermatum zoospores, the B. stearothermophilus YC4194 maintained the high population density in rhizosphere soil upto 10$^{7}$ cfu/g until 15 days after treatment.

• Microbiology and Biotechnology Letters
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• v.22 no.6
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• pp.599-606
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• 1994

Bacillus stearothermomophilus, a strong xylan degrader, was confirmed to express multiple esterase activities in addition to the major xylanolytic enzymes. One of the genes encoding the esterases was isolated from the genomic library of B. stearothermophilus constructed with EcoRl restriction endonuclease and pBR322 plasmid. Three recombinant plasmids showing the tributyrin degrading activity were selected from approximately 7, 000 E. coli HB101 transformants, and were found to have the same insert of a 3.2 kb DNA fragment. Restriction mapping and hybridization studies revealed that the gene(estII) on the hybrid plasmid (pKMG7) had originated from the B. stearothermophilus chromosome, and was distinct from the estl, another esterase gene of B. stearothermophilus isolated in the previous work. The E. coli cells harboring pKMG7 produced an acetylxylan esterase that exibited similar substrate specificity to the esterase encoded by the estI gene.

• Microbiology and Biotechnology Letters
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• v.17 no.4
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• pp.289-294
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• 1989

A bacterial strain capable of producing high level of extracellular xylanase was isolated from soil. The characteristics of the isolated strain No.236 were identified to be Bacillus stearothermophilus. The maximal xylanase production was observed in the medium containing 0.75% xylan, 0.35% yeast extract, 1.06% $K_2$HPO$_4$and 0.05% CaCO$_3$with initial pH of 6.5 when the strain was cultured at 5$0^{\circ}C$ for 28 hrs with reciprocal shaking. Hydrolysis of xylan by the xylanase revealed that xylose was the only product of the reaction. This suggested that the enzyme produced by Bacillus stearothermophilus No. 236 was an exe-acting xylanase.

• Microbiology and Biotechnology Letters
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• v.20 no.3
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• pp.344-347
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• 1992

Simultaneous liquefaction and cyclodextrin (CD) production were conducted on potato starch using cyclomaltodextrin glucanotransferase (CGTase) from a mutant strain MNNG 8 of Bacillus stearothermophilus No. 239. A high concentration (30%) of potato starch was converted to cyc1o-dextrins (CDs) with 29% yield in the conditions of pH 6.0, temperature $80^{\circ}C$, 4.3 mM $CaCl_2$, CGTase addition of 3.0 dextrinizing activity unit (DAU) at $40^{\circ}C$/g starch.

• Microbiology and Biotechnology Letters
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• v.30 no.4
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• pp.293-297
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• 2002

The cyclodextrin glucanotransferase (CGTase) gene from Bacillus stearothermophilus NO2 was expressed in Saccharomyces cerevisiae 2805 under the adhl promoter. The CGTase was purified from S. cerevisiae 2805/pVT-CGTS. The purified enzyme exhibited a optima of activity around pH 7.0 and $65^{\circ}C$. Thermal stability of the enzyme was increased fairly as compared with the CGTase of B. stearothermophilus NO2. The conversion yield of cyclodextrin (CD) and the production ratio of $\alpha$-, $\beta$,-, ${\gamma}$-CD from starch were showed similarly aspect to the CGTase of B. stearothermophilus NO2.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.56-59
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• 2000

Thermophilic bacterium, Bacillus stearothermophilus NUB3621, was engineered to produce ethanol from glucose by introducing cloned thermostable pyruvate decarboxylase and alcohol dehydrogenase genes. A novel promoter sequence was screened and used for the enhancement of these two enzymes. Successful redirection of metabolic flux into ethanol was obtained. In addition, gene expression profiling using Bacillus subtilis DNA microarray was analyzed to overcome the intrinsic low glucose utilization of B.stearothermophilus. Many known and unknown genes were identified to be up or down regulated under glucose-containing media.

• Journal of Microbiology and Biotechnology
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• v.2 no.2
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• pp.115-121
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• 1992

In order to broaden the spectrum of substrate utilization of a Gram negative bacterium Zymomonas mobilis which has a great potential as an industrial ethanol producing microorganism, cloning of $\alpha$-amylase gene into Z. mobilis ZM4 was tried. The $\alpha$-amylase gene was isolated from Bacillus stearothermophilus. By Southern blot analysis, it was proven that the $\alpha$-amylase gene fragment was originated from a naturally occuring plasmid of B. stearothermophilus ATCC 31195. To place $\alpha$-amylase gene under the control of Z. mobilis promoter, two different Z. mobilis expression vectors, pZA26 and pLOI204, were used. The truncated $\alpha$-amylase gene was then introduced into these vectors. Both qualitative and quantitative activities of $\alpha$-amylase were observed in Z. mobilis cells harboring these plasmids with the $\alpha$-amylase gene inserted. Gas chromatographic analysis of ethanol showed that one of the Z. mobilis transconjugants was capable of producing 67 mM ethanol from rich medium(RM) containing 5% soluble starch as a sole carbon source.

• Journal of Microbiology and Biotechnology
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• v.8 no.1
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• pp.21-27
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• 1998

The xylA gene of Bacillus stearothermophilus encoding the major ${\beta}$-xylosidase was previously cloned and sequenced. In the present study we examined the regulation of the cloned xylA gene expression in Bauillus subtilis MW15 carrying the xylA::aprA fusion plasmids. The induction of the fused xylA gene expression remained uninfluenced by any of the carbon sources tested but the gene expression was repressed about 2-3 fold in the presence of glucose. Two CRE-like sequences (CRE-1: nucleotides ＋ 124 to ＋136 and CRE-2: ＋247 to ＋259) were recognized within the reading frame region of the xylA gene. The deletion experiments showed that the CRE-2 sequence had a role in catabolite repression (CR) as a true CRE of the xylA gene, but the CRE-1 had no effect on CR of the xylA gene expression. Surprisingly, the deletion of the CRE- 1 sequence reduced about 2~3 fold of the expression of the xylA fused gene. The repression ratios of the xylA gene expression were estimated to be about 0.4 from the assay of subtilisin activity, and about 0.3 at the level of transcription by determining the amounts of xylA transcripts in B. subtilis. While, the level of CR of the xylA gene was assessed to be about l0-fold in previous work when the relative amounts of the xylA transcripts were measured in B. stearothermophilus.