• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.7
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• pp.1115-1124
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• 2013

The present study was conducted to ensure the diversity of domestic solar salt by analyzing the composition and microbiological characteristics of solar salt (from Docho island: DS) and the flower of salt produced in different Korean salt flats (Sinui island: SF, Bigum island: BF, and Docho island: DF). The analyses showed that the moisture content of the three types of flower of salt and solar salt ranged from 10.54~13.82% and NaCl content ranged from 78.81~84.61%. The mineral content of those salts ranged from 3.57~5.51%. The content of insoluble matter in these salts was $0.01{\pm}0.00{\sim}0.05{\pm}0.00%$. The sand content of these salts was $0.01{\pm}0.01{\sim}0.03{\pm}0.01%$. By Hunter's color value analysis, the color of the flower of salt was brighter and whiter than solar salt. The salinity of the flower of salt was a little higher than solar salt as well. The magnesium and potassium ion content of DF was $9,886.72{\pm}104.78mg/kg$ and $2,975.23{\pm}79.73mg/kg$, respectively, which was lower than the content in SF, BF, and DS. The heavy metal content of all salts was acceptable under the Korean Food Sanitation Law. The flower of salt was confirmed to be sweeter and preferable to solar salt. More than 80% of the solar salt crystals were 2~3 mm in size, whereas crystals from the flower of salt were 0.5~2 mm in size. The bacterial diversity of DF and DS were investigated by culture and denaturing gradient gel electrophoresis (DGGE) methods. The number of cultured bacteria in flower of salt was approximately three times more than solar salt. By DGGE analysis, major microbes of DF were Maritimibacter sp., Cupriavidus sp., and unculturable bacteria, and those of DS were Cupriavidus sp., Dunalidella salina and unculturable bacteria. The results of DGGE analysis showed that major microorganisms in solar salts were composed of unidentified and unculturable bacteria and only a few microorganisms were culturable.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.5
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• pp.509-516
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• 2010

This study investigates characteristics of diesel degradation and variations of microbial community with the soil enrichment cultures. The cultures has yellow(YE-5) and transparent color's(WH-5) colony on solid plate medium. The bacillus type of YE-5 and WH-5 cultures showed diesel degradation at the rate of 99.07mg-Diesel/$L{\cdot}day$ and 57.82mg-Diesel/$L{\cdot}day$ in the presence of 1%(v/v) initial diesel concentration. Diesel degradation was 1.7 times faster than WH-5 culture. YE-5 or WH-5 culture could degrade a wide range of diesel compounds from $C_8$ to $C_24$. Microbial community analysis by PCR-DGGE technique shows that Psedomonas, Klebsiella, Escherichia and Stenotrophomonas as proteobacteria take role on the diesel degradation. uncultured Senotrophomonas sp. was only detected with YE-5 culture. It is concluded that proper combination of the microorganism should be present to stimulate the degradation of diesel and further studies are recommended for the effect of uncultured Senotrophomonas sp. or Escherichia hermannii on diesel degradation.

• Korean Chemical Engineering Research
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• v.53 no.1
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• pp.71-77
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• 2015

A fluidized biofilter was filled with Pseudomonas sp. and Bacillus cereus/thuringiensis-fixed waste-tire crumb media and was run to treat authentic textile-dyeing wastewater mixed with alkaline polyester-weight-reducing wastewater. As a result, its removal efficiency of $COD_{Cr}$ and color were 75~80% and 67%, respectively. In addition, upon constructing hybrid-recirculating system composed of the fluidized biofilter and a 450 W-UV/photocatalytic reactor, only fluidized biofilter was run bypassing UV/photocatalytic reactor at stage I. Subsequently, the hybrid system was continuously run at stage II-i, ii and iii. At stage II-i, the total removal efficiency of $COD_{Cr}$ was enhanced to be 80~85%, compared to 75% at stage I, owing to 20~30% removal efficiency of the UV/photocatalytic reactor. However, at stage II-i, the total removal efficiency of color was enhanced to be 65~70%, compared to 45~65% at stage I, even though the removal efficiency of the UV/photocatalytic reactor was tantamount to merely 0~5%. As far as the removal efficiency of fluidized biofilter of the hybrid-recirculating system is concerned, its removal efficiency of color was enhanced by the synergy effect of the hybrid-recirculating system unlike $COD_{Cr}$. Besides, despite of the increase of hybrid-recirculating system-recycle ratio, the deactivation of photo-catalytic activity was scarcely observed to eliminate the color while its irreversible deactivation was observed to eliminate $COD_{Cr}$.

• Journal of Microbiology and Biotechnology
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• v.33 no.3
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• pp.387-397
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• 2023

Cytochrome P450 (CYP) is a heme-containing enzyme that catalyzes hydroxylation reactions with various substrate molecules. Steroid hydroxylases are particularly useful for effectively introducing hydroxyl groups into a wide range of steroids in the pharmaceutical industry. This study reports a newly identified CYP steroid hydroxylase (BaCYP106A6) from the bacterium Bacillus sp. and characterizes it using an in vitro enzyme assay and structural investigation. Bioconversion assays indicated that BaCYP106A1 catalyzes the hydroxylation of progesterone and androstenedione, whereas no or low conversion was observed with 11β-hydroxysteroids such as cortisol, corticosterone, dexamethasone, and prednisolone. In addition, the crystal structure of BaCYP106A6 was determined at a resolution of 2.8 Å to investigate the configuration of the substrate-binding site and understand substrate preference. This structural characterization and comparison with other bacterial steroid hydroxylase CYPs allowed us to identify a unique Arg295 residue that may serve as the key residue for substrate specificity and regioselectivity in BaCYP106A6. This observation provides valuable background for further protein engineering to design commercially useful CYP steroid hydroxylases with different substrate specificities.

• Mycobiology
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• v.35 no.1
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• pp.25-29
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• 2007

A newly synthesized Nickel (II) tyrosine complex was screened as potential antimicrobial agent against a number of medically important bacteria (Bacillus subtilis, Streptococcus ${\beta}$-haemolytica, Escherichia coli, Shigella dysenterae) and fungi (Aspergillus fumigatus, Candida albicans, Aspergillus niger, Aspergillus flavus, Penicillium sp.) strains. were used for antifungal activity. The antimicrobial activity was evaluated using the Agar Disc method. Moreover, the minimum inhibitory concentration of the complexes was determined against the same pathogenic bacteria and the values were found between $4{\sim}64\;{\mu}g\;ml^{-1}$. Brine shrimp bioassay was carried out for cytotoxicity measurements of the complexes. The $LC_{50}$ values were calculated after probit transformation of the resulting mortality data and found to be 6 ${\mu}g\;ml^{-1}$.

• The Plant Pathology Journal
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• v.33 no.5
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• pp.488-498
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• 2017

The aim of this study was to identify volatile and agardiffusible antifungal metabolites produced by Bacillus sp. G341 with strong antifungal activity against various phytopathogenic fungi. Strain G341 isolated from four-year-old roots of Korean ginseng with rot symptoms was identified as Bacillus velezensis based on 16S rDNA and gyrA sequences. Strain G341 inhibited mycelial growth of all phytopathogenic fungi tested. In vivo experiment results revealed that n-butanol extract of fermentation broth effectively controlled the development of rice sheath blight, tomato gray mold, tomato late blight, wheat leaf rust, barley powdery mildew, and red pepper anthracnose. Two antifungal compounds were isolated from strain G341 and identified as bacillomycin L and fengycin A by MS/MS analysis. Moreover, volatile compounds emitted from strain G341 were found to be able to inhibit mycelial growth of various phytopathogenic fungi. Based on volatile compound profiles of strain G341 obtained through headspace collection and analysis on GC-MS, dimethylsulfoxide, 1-butanol, and 3-hydroxy-2-butanone (acetoin) were identified. Taken together, these results suggest that B. valezensis G341 can be used as a biocontrol agent for various plant diseases caused by phytopathogenic fungi.

• Journal of Microbiology
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• v.40 no.1
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• pp.33-37
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• 2002

An enzymatic reaction for the production of D-alanine from D-aspartic acid and pyruvate as substrates by a thermostable D-amino acid aminotransferase (D-AAT) was investigated at various conditions In the temperature range of 40-70$\^{C}$ and pH range of 6.0-9.5. The D-AAT was produced with recombinant E. coli BL21, which hosted the chimeric plasmid pTLK2 harboring the D-AAT from the novel thermophilic Bacillus sp. LK-2. The enzyme reaction was shown to follow the Ping Pong Bi Bi mechanism. The K$\_$m/ values for D-aspartic acid and pyruvate were 4.38 mar and 0.72 mM, respectively. It was observed that competitive inhibition by D-alanine, the product of this reaction, was evident with the inhibition constant K$\_$i/ value of 0.1 mM. A unique feature of this reaction scheme is that the decorboxylation of oxaloacetic acid, one of the products, spontaneously produces pyruvate. Therefore, only a catalytic amount of pyruvate is necessary for the enzyme conversion reaction to proceed. A typical time-course kinetic study skewed that D-alanine up to 88 mM could be produced from 100 mM of D-aspartic acid with a molar yield of 1.0.

• Biodesign
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• v.6 no.4
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• pp.84-91
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• 2018

Spo0F is a response regulator that modulates sporulation, undergoes phosphorylation for phosphorelay signal transduction, and interacts with various regulatory proteins; however, the mechanisms through which phosphorylation induces structural changes and regulates interactions with binding partners remain unclear. Here, we determined the unphosphorylated crystal structure of Spo0F from the psychrophilic bacterium Paenisporosarcina sp. TG-14 (PaSpo0F) and established a phosphorylation-state structural model. We found that PaSpo0F underwent structural changes (Lys54 and Lys102) by phosphorylation and generated new interactions (Lys102/Gln10 and Lys54/Glu84) to stabilize the ${\beta}4/{\alpha}4$ and ${\beta}1/{\alpha}1$ loop structures, which are important target-protein binding sites. Analysis of Bacillus subtilis Spo0 variants revealed movement by BsSpo0F Thr82 and Tyr84 residues following interaction with BsSpo0B, providing insight into the movement of corresponding residues in PaSpo0F (Thr80 and Tyr82), with further analysis of BsSpo0F/BsRapH interaction revealing alterations in the ${\beta}4/{\alpha}4$ loop region. These results suggest that phosphorylation-induced structural rearrangement might be essential for PaSpo0F activation and expand the understanding of Spo0F-specific activation mechanisms during sporulation.

• Microbiology and Biotechnology Letters
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• v.36 no.4
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• pp.307-313
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• 2008

The yeast surface expression system, pCTXYN (6.8 kb), of Bacillus endoxylanase gene (xynB, 642 bp) was constructed and introduced into Saccharomyces cerevisiae EBY100 cell. The transformed yeast cell showing the highest endoxylanase activity was selected through the active staining of colonies grown on YPDG medium containing xylan. With the yeast transformant, EBY100/pCTXYN, grown on galactose containing medium, it was found that the endoxylanase was successfully displayed on the yeast cell surface and the xylooligosaccharides were efficiently produced from xylan. The most of endoxylanase activity was detected in the cell fraction and reached about 1.9 unit/mL after 48 h cultivation. The optimized conditions for xylooligosaccharides production from xylan were determined as follows: substrate and its concentration, oat spelt xylan 6%; concentration of yeast whole-cell, 5 unit/mL; temperature, $50^{\circ}C$, and reaction time $2{\sim}4\;h$. When the oat spelts xylan and corncob xylan were hydrolyzed by treatment with cell surface-displayed endoxylanase, xylotriose was formed as a main product.

• The Korean Journal of Food And Nutrition
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• v.26 no.2
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• pp.249-257
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• 2013

This study is being performed to confirm the container effects during the fermentation processes of kimchi. Kimchi fermentation was prepared in the laboratory with four different types of containers; namely, a traditional Onggi vessel (Korean traditional clay pot, TOV), plastic airtight covered Onggi vessel (PAOV), plastic covered vessel (PCV) and plastic airtight covered vessel (PACV). The kimchi fermentation in the different containers was followed by taking samples at 48 hour intervals for 10 days. In all fermentation containers, the pH changes of kimchi were decreased with fermentation days, while salt content was the same for all types of containers. The number of lactic acid bacteria in kimchi were $1.09{\times}10^8$ $CFU/m{\ell}$ at first. But the TOV, PAOV, PCV, and PACV after fermentation for 10 days were $1.42{\times}10^{10}$, $9.13{\times}10^9$, $4.93{\times}10^9$ and $7.46{\times}10^9$ $CFU/m{\ell}$, respectively. The kimchi fermented in the TOV with the most dominant bacterial species were the following 5 strains: Bacillus subtilis, B. licheniformis, B. safensis, Lactobacillus brevis and B. pumilus. The use of different types of containers therefore influenced the number of L. brevis and the four Bacillus species. in kimchi, and may influence the characteristics of the fermented kimchi products. The TOV offered the greatest L. brevis numbers and suggested that it could be the best suited for preparing traditional kimchi fermentation.