• Journal of Microbiology and Biotechnology
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• v.16 no.4
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• pp.613-618
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• 2006

Two endoxylanases from an alkaliphilic bacterium, Bacillus halodurans C-1, were purified 3.8- and 7.9- fold with specific activities of 9.4 and 19.8U/mg protein, respectively. The molecular masses of both purified enzymes were 23 and 47 kDa, respectively, and 23 kDa xylanase I (Xyl I) exhibited an optimum pH at 7.0, whereas 47 kDa xylanase II (Xyl II) showed a broad pH range of 5.0 to 9.0. The temperature optima of both xylanases were $60^{\circ}C\;and\;70^{\circ}C$, respectively. Both were stable in the pH range of 6.0 to 9.0 and 5.0 to 10.0, respectively, and they were stable up to $60^{\circ}C\;and\;70^{\circ}C$, respectively. The $K_m\;and\;V_{max}$ of Xyl I were 4.33mg/ml and $63.5{\mu}mol/min/mg$, respectively, whereas Xyl II had a $K_m$ value of 0.30 mg/ml and $V_{max}$ of $210{\mu}mol/min/mg$. Both xylanases hydrolyzed xylans from birchwood, oat spelt, and larchwood. However, they showed different modes of action; a series of xylooligosaccharides larger than xylotriose were released as the major products by Xyl I, whereas xylobiose and xylotriose were the main products by Xyl II. The maximum synergistic action of the two enzymes on hydrolysis of xylan was 2.16 with the ratio of Xyl I to Xyl II at 1:9.

• Journal of Microbiology and Biotechnology
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• v.30 no.2
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• pp.155-162
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• 2020

Acetyl xylan esterase (AXE; E.C. 3.1.1.72) is one of the accessory enzymes for xylan degradation, which can remove the terminal acetate residues from xylan polymers. In this study, two genes encoding putative AXEs (LaAXE and BhAXE) were cloned from Lactobacillus antri DSM 16041 and Bacillus halodurans C-125, and constitutively expressed in Escherichia coli. They possess considerable activities towards various substrates such as p-nitrophenyl acetate, 4-methylumbelliferyl acetate, glucose pentaacetate, and 7-amino cephalosporanic acid. LaAXE and BhAXE showed the highest activities at pH 7.0 and 8.0 at 50℃, respectively. These enzymes are AXE members of carbohydrate esterase (CE) family 7 with the cephalosporine-C deacetylase activity for the production of antibiotics precursors. The simultaneous treatment of LaAXE with Thermotoga neapolitana β-xylanase showed 1.44-fold higher synergistic degradation of beechwood xylan than the single treatment of xylanase, whereas BhAXE showed no significant synergism. It was suggested that LaAXE can deacetylate beechwood xylan and enhance the successive accessibility of xylanase towards the resulting substrates. The novel LaAXE originated from a lactic acid bacterium will be utilized for the enzymatic production of D-xylose and xylooligosaccharides.

• Journal of Microbiology and Biotechnology
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• v.12 no.5
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• pp.773-779
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• 2002

A gene (hap) encoding aminopeptidase from the chromosomal DNA of Bacillus licheniformis was cloned. The gene is 1,347 bp long and encodes a 449 amino acid preproprotein with a major mature region of 401 amino acids (calculated molecular mass 43,241 Da). N-Terminal sequence of the purified protein revealed a potential presence of N-terminal propeptide. The deduced primary amino acid sequence and the mass analysis of the purified protein suggested that a C-terminal peptide YSSVAQ was also cleaved off by a possible endogeneous protease. Tho amino acid sequence displayed 58% identity with that of the aminopeptidase from alkaliphilic Bacillus halodurans. This bacterial enzyme was overexpressed in recombinant Escherichia coli and Bacillus subtilis cells. Clones containing the intact hap gene, including its own promoter and signal sequence, gave rise to the synthesis of extracellular and thrmostable enzyme by B. subtilis transformants. The secreted protein exhibited the same biochemical properties and the similar apparent molecular mass as the B. lichenzyormis original enzyme.

• Microbiology and Biotechnology Letters
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• v.20 no.3
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• pp.289-294
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• 1992

Twenty-four bacterial strains among alkalophillic bacteria isolated from soil samples were examined for the presence of type II restriction endonuclease in aerobic culture. One strain was found to contain specific enzyme to cleave lambda DNA. The characteristics of this microorganism is the ability to grow well in alkalophilic and high temperature condition, that is at pH 10.3 and $50^{\circ}C$. This strain was tentatively identified to Bacillus alkaloPhilus subsp. halodurans when morphological, physiological and biochemical characteristics were examined. The enzyme was purified from crude extract by streptomycin sulfate, ammonium sulfate precipitation, which was followed by DEAE-cellulose and phosphocellulose ion exchange column chromatography, and the subunit molecular weight was about, 32,000 daltons by polyacrylamide gel electrophoresis containing 0.1% SDS.

• Journal of the Korean Geotechnical Society
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• v.31 no.1
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• pp.37-46
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• 2015

In this study, a blast furnace slag with the alkaliphilic microorganism (Bacillus halodurans) alkaline activator was used to cement natural soils in the field. A low-cost and massive microbial solution for cementation of field soils was produced and compared with existing microbial culture in terms of efficiency. A field soil was prepared for three different cementation areas: a cemented ground with microbial alkaline activator (Microbially-treated soil), a cemented ground with ordinary Portland cement (Cement-treated soil), and untreated ground (Non-treated soil). The testing ground was prepared at a size of 2.6 m in width, 4 m in length, and 0.2 m in depth. After 28 days, a series of unconfined compression tests on the cement-treated and microbially-treated soils were carried out. On the other hand, a torvane test was carried out for non-treated soil. The strength of field soils treated with microorganism was 1/5 times lower than those of cement-treated soil but is 6 times higher than non-treated soil. The pH measured from microbially-treated soil was about 10, which is lower than that of cement-treated soil (pH = 11). Therefore, it is more eco-friendly than Portland cemented soils. The C-S-H hydrates were found in both cement- and microbially-treated soils through SEM-EDS analyses and cement hydrates were also found around soil particles through SEM analysis.

• Journal of Microbiology and Biotechnology
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• v.17 no.1
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• pp.29-36
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• 2007

The xynA gene encoding the xylanase A of Paenibacillus sp. DG-22 was isolated with a DNA probe obtained by PCR amplification, using degenerated primers deduced from the amino acid residues of the known N-terminal region of the purified enzyme and the conserved region in the family 11 xylanases. The positive clones were screened on the LB agar plates supplemented with xylan, by the Congo-red staining method. The xynA gene consists of a 630-bp open reading frame encoding a protein of 210 amino acids, and the XynA preprotein contains a 28-residues signal peptide whose cleavage yields a l82-residues mature protein of a calculated molecular weight of 20,000Da and pI value of 8.77. The cloned DNA fragment also has another ORF of 873 nucleotides that showed 76% identity to the putative transcriptional activator of Bacillus halodurans C-125. Most of the xylanase activity was found in the periplasmic space of E. coli. The xynA gene was subcloned into pQE60 expression vector to fuse with six histidine-tag. The recombinant xylanase A was purified by heating and immobilized metal affinity chromatography. The optimum pH and temperature of the purified enzyme were 6.0 and $60^{\circ}C$, respectively. This histidine-tagged xylanase A was less thermostable than the native enzyme.