• Asian-Australasian Journal of Animal Sciences
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• v.26 no.1
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• pp.50-58
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• 2013

A facultative bacterium producing cellulolytic and hemicellulolytic enzymes was isolated from the rumen of a native Korean goat. The bacterium was identified as a Bacillus licheniformis on the basis of biochemical and morphological characteristics and 16S rDNA sequences, and has been designated Bacillus licheniformis JK7. Endoglucanase activities were higher than those of ${\beta}$-glucosidase and xylanase at all temperatures. Xylanase had the lowest activity among the three enzymes examined. The optimum temperature for the enzymes of Bacillus licheniformis JK7 was $70^{\circ}C$ for endoglucanase (0.75 U/ml) and $50^{\circ}C$ for ${\beta}$-glucosidase and xylanase (0.63 U/ml, 0.44 U/ml, respectively). All three enzymes were stable at a temperature range of 20 to $50^{\circ}C$. At $50^{\circ}C$, endoglucanse, ${\beta}$-glucosidase, and xylanase had 90.29, 94.80, and 88.69% residual activity, respectively. The optimal pH for the three enzymes was 5.0, at which their activity was 1.46, 1.10, and 1.08 U/ml, respectively. The activity of all three enzymes was stable in the pH range of 3.0 to 6.0. Endoglucanase activity was increased 113% by $K^+$, while $K^+$, $Zn^+$, and tween 20 enhanced ${\beta}$-glucosidase activity. Xylanase showed considerable activity even in presence of selected chemical additives, with the exception of $Mn^{2+}$ and $Cu^{2+}$. The broad range of optimum temperatures (20 to $40^{\circ}C$) and the stability under acidic pH (4 to 6) suggest that the cellulolytic enzymes of Bacillus licheniformis JK7 may be good candidates for use in the biofuel industry.

• Journal of Microbiology and Biotechnology
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• v.6 no.2
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• pp.79-85
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• 1996

By using a T7 expression system, a large amount of Bacillus stearothermophilus endo-xylanase A (XynA) could be produced in Escherichia coli cells. The overproduced enzyme formed inclusion bodies, and so the protein could be more easily purified to homogeneity. The molecular weight of the purified enzyme was estimated to be 22 kDa by SDS-polyacrylamide gel electrophoresis and 43 kDa by Sephacryl S-200 gel filtration, suggesting that the native enzyme was a homodimer. The pI value was determined to be 8.4. The Michaelis constants for birchwood xylan and oat spelts xylan were calculated to be 3.83 mg/ml and 5.03 mg/ml, respectively, and the $V_{max}$ max/ values for both xylans were 2.86 $\mu mole$/min. The purified enzyme was most active at $55^{\circ}C$ and pH 8.0, and stable up to $60^{\circ}C$ and in the near neutral pH range. From the zymogram, Bacillus stearothermophilus was found to have at least three xylanases and the purified one was the smallest among them.

• Microbiology and Biotechnology Letters
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• v.33 no.1
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• pp.24-28
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• 2005

A bacterial strain D­1 found to have potent fibrinolytic activity was isolated from Korean traditional Doenjang. It was identified as Bacillus sp. based on its 16S rRNA sequence analysis, morphological and physiological characteristics.

• Journal of Microbiology and Biotechnology
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• v.13 no.5
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• pp.738-744
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• 2003

The gene ADH encoding NAD-dependent alcohol dehydrogenase from Bacillus stearothennophilus was cloned and overexpressed as a GST fusion protein at a high level in Escherichia coli. The expressed fusion protein was purified simply by glutathione affinity chromatography. GST fusion protein was then cleaved by thrombin, while soluble enzyme was further purified by glutathione affinity chromatography. The recombinant enzyme had the same elctrophoretic mobility as the native enzyme from Bacillus stearothennophilus. The recombinant enzyme catalyzed the oxidation of a number of alcohols and exhibited high activities towards secondary alcohols. The $K_m\;and\;V_{max}$ values of the recombinant enzyme for ethanol were 5.11 mM and 61.35 U/mg, respectively. Pyridine and imidazole notably inhibited the enzymatic activity. The activity of the recombinant enzyme optimally proceeded at pH 9.0 and $70^{\circ}C$. The midpoint of the temperature-stability curve for the recombinant enzyme was approximately $68^{\circ}C$, and the enzyme was not completely inactivated even at $85^{\circ}C$. The recombinant enzyme showed a high resistance towards denaturing agents (0.05% SDS, 0.1 M urea). Therefore, due to its stability and relatively broad substrate specificity, the recombinant enzyme could be utilized in bio-industrial processes and biosensors.

• Journal of Microbiology and Biotechnology
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• v.17 no.1
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• pp.37-43
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• 2007

A gene encoding inulin fructotransferase (di-D-fructofuranose 1,2': 2,3' dianhydride [DFA III]-producing IFTase, EC 4.2.2.18) from Bacillus sp. snu-7 was cloned. This gene was composed of a single, 1,353-bp open reading frame encoding a protein composed of a 40-amino acid signal peptide and a 410-amino acid mature protein. The deduced amino acid sequence was 98% identical to Arthrobacter globiformis C11-1 IFTase (DFA III-producing). The enzyme was successfully expressed in E. coli as a functionally active, His-tagged protein, and it was purified in a single step using immobilized metal affinity chromatography. The purified enzyme showed much higher specific activity (1,276 units/mg protein) than other DFA III-producing IFTases. The recombinant and native enzymes were optimally active in very similar pH and temperature conditions. With a 103-min half-life at $60^{\circ}C$, the recombinant enzyme was as stable as the native enzyme. Acidic residues and cysteines potentially involved in the catalytic mechanism are proposed based on an alignment with other IFTases and a DFA IIIase.

• Journal of Microbiology and Biotechnology
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• v.22 no.3
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• pp.407-415
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• 2012

An endophytic bacterium, Bacillus thuringiensis GS1, was isolated from bracken (Pteridium aquilinum) and found to have maximal production of chitinase (4.3 units/ml) at 5 days after culture. This study investigated the ability of B. thuringiensis GS1 to induce resistance to Rhizoctonia solani KACC 40111 (RS) in cucumber plants. Chitinase activity was greatest in RS-treated plants at 4 days. ${\beta}$-1,3-Glucanase activity was highest in GS1-treated plants at 5 days. Guaiacol peroxidase (GPOD) activity increased continuously in all treated plants for 5 days. Ascorbate peroxidase (APX) activity in RS-treated plants was increased 1.5-fold compared with the control at 4 days. Polyphenol oxidase (PPO) activity in RS-treated plants was increased 1.5-fold compared with the control at 3 days. At 5 days after treatment, activity staining revealed three bands with chitinase activity (Ch1, Ch2, and Ch3) on SDS-PAGE of cucumber plants treated with GS1+RS, whereas only one band was observed for RS-treated plants (Ch2). One GPOD isozyme (Gp1) was also observed in response to treatment with RS and GS1+RS at 4 days. One APX band (Ap2) was present on the native-PAGE gel of the control, and GS1- and GS1+RS-treated plants at 1 day. PPO bands (Po1 and Po2) from RS- and GS1+RS-treated plants were stronger than in the control and GS1-treated plants upon native-PAGE at 5 days. Taken together, these results indicate that the induction of PR proteins and defense-related enzymes by B. thuringiensis GS1 might have suppressed the damping-off caused by R. solani KACC 40111 in cucumber plants.

• Animal Bioscience
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• v.35 no.6
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• pp.869-883
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• 2022

Objective: The aim of study was to investigate the effects of in-feed supplementation of Bacillus amyloliquefaciens (BA) and Saccharomyces cerevisiae (SC) on growth performance, gut integrity, and microbiota modulations in red-feathered native chickens (RFCs). Methods: A total of 18,000 RFCs in a commercial farm were evenly assigned into two dietary treatments (control diet; 0.05% BA and 0.05% SC) by randomization and raised for 11 weeks in two separate houses. Fifty RFCs in each group were randomly selected and raised in the original house with the partition for performance evaluations at the age of 9 and 11 weeks. Six non-partitioned RFCs per group were randomly selected for analyses of intestinal architecture and 16S rRNA metagenomics. Results: Feeding BA and SC increased the body weight and body weight gain, significantly at the age of 11 weeks (p<0.05). The villus height/crypt ratio in the small intestines and Firmicutes to Bacteroidetes ratio were also notably increased (p<0.05). The supplementation did not disturb the microbial community structure but promote the featured microbial shifts characterized by the significant increments of Bernesiella, Prevotellaceae_NK3B31_group, and Butyrucimonas, following remarkable decrements of Bacteroides, Rikenellaceae_RC9_gut_group, and Succinatimonas in RFCs with growth benefits. Besides, functional pathways of peptidoglycan biosynthesis, nucleotide excision repair, glycolysis/gluconeogenesis, and aminoacyl transfer ribonucleic acid (tRNA) biosynthesis were significantly promoted (p<0.05). Conclusion: In-feed supplementation of BA and SC enhanced the growth performance, improved mucosal architectures in small intestines, and modulated the cecal microbiota and metabolic pathways in RFCs.

• Microbiology and Biotechnology Letters
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• v.35 no.3
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• pp.203-209
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• 2007

Soybean milk cake (SMC) was used for the solid-state fermentation by Bacillus subtilis PUL-A isolated from soybean milk cake. In the presence of 5% glutamate the maximum production of biopolymer (59.9 g/kg) was performed by fermentation at $42^{\circ}C$ for 24 hr. The recovered biopolymer was consisted of 87% $\gamma$-polyglutamic acid with molecular weight of $1.3{\times}10^6$ dalton and other biopolymer. The biopolymer solution showed the great decrease in consistency below pH 6.0, regardless of the molecular weight of PGA. Biopolymer solution has a typical pseudoplastic flow behavior and yield stress. The consistency of biopolymer solution was greatly decreased by increasing heating time and temperature in acidic condition compared to the alkaline condition. In kaolin clay suspension, the flocculating activity of biopolymer was the highest value with 15 mg/L biopolymer and 4.5 mM $CaCl_2$, but decreased greatly with $FeCl_3$. The flocculating activity of biopolymer was maximum at pH5, but decreased drastically by heating at $60{\sim}100^{\circ}C$. In particular, biopolymer with native PGA showed the efficient flocculating activity compared to that of modified biopolymer containing low molecular weight of PGA.

• Journal of Microbiology and Biotechnology
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• v.9 no.6
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• pp.861-869
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• 1999

An extracellular protease was purified to homogeneity from the culture supernatant of psychrotrophic bacteria Bacillus sp. JH 108 using procedures including ammonium sulfate fractionation, anion exchange chromatography, gel filtration chromatography, and cation exchange chromatography. The enzyme exhibited a molecular weight of 36 kDa, an optimum pH of 8 to 9, and optimum temperature of $60^{\circ}C$. The enzyme preferentially hydrolyzed leucine at the N-terminus of peptides and thus can be classified as an aminopeptidase. It was strongly inhibited by metal chelating agents such as EDTA and l, l0-phenanthroline. The activity lost by EDTA was restored with $Zn^{2+}{\;}or{\;}Co^{2+}$. These divalent cations also stimulated the native enzyme. This suggests that the enzyme is a metalloprotease acting as a leucine aminopeptidase.

• Journal of Microbiology and Biotechnology
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• v.22 no.6
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• pp.788-792
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• 2012

We report the computational structural simulation of the Cry1Ab19 toxin molecule from B. thuringiensis BtX-2 based on the structure of Cry1Aa1 deduced by x-ray diffraction. Validation results showed that 93.5% of modeled residues are folded in a favorable orientation with a total energy Z-score of -8.32, and the constructed model has an RMSD of only $1.13{\AA}$. The major differences in the presented model are longer loop lengths and shortened sheet components. The overall result supports the hierarchical three-domain structural hypothesis of Cry toxins and will help in better understanding the structural variation within the Cry toxin family along with facilitating the design of domain-swapping experiments aimed at improving the toxicity of native toxins.