• Korean Journal of Food Science and Technology
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• v.29 no.5
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• pp.1021-1027
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• 1997

We examined some properties of yeast cell wall lytic enzyme produced by Dicyma sp. YCH-37. Several metal ions, reducing reagents, and chemical modifiers have little effects on the lytic activity, except guanidine-HCl. Yeast cells of early log phase were more susceptible to the enzyme than those of stationary phase, and heat-treated cells were more easily lysed than intact living ones. Yeast cells pretreated with organic solvents such as butanol and acetone were more susceptible to the enzyme than intact living ones. Yeast cells cultured in Yeast extract-Malt extract medium containing 0.5 M ammonium sulfate were easily lysed by the lytic enzyme, and yeast cells cultured without shaking were more easily lysed by the enzyme than those with shaking. When SDS, ${\beta}-mercaptoethanol$, Triton X-100, sodium sulfite, and KCl were added to enzyme reaction mixture each, lysis of yeast cells was more effective.

• Journal of Microbiology and Biotechnology
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• v.34 no.2
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• pp.436-456
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• 2024

Several thermostable proteases have been identified, yet only a handful have undergone the processes of cloning, comprehensive characterization, and full exploitation in various industrial applications. Our primary aim in this study was to clone a thermostable alkaline protease from a thermophilic bacterium and assess its potential for use in various industries. The research involved the amplification of the SpSKF4 protease gene, a thermostable alkaline serine protease obtained from the Geobacillus thermoglucosidasius SKF4 bacterium through polymerase chain reaction (PCR). The purified recombinant SpSKF4 protease was characterized, followed by evaluation of its possible industrial applications. The analysis of the gene sequence revealed an open reading frame (ORF) consisting of 1,206 bp, coding for a protein containing 401 amino acids. The cloned gene was expressed in Escherichia coli. The molecular weight of the enzyme was measured at 28 kDa using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The partially purified enzyme has its highest activity at a pH of 10 and a temperature of 80℃. In addition, the enzyme showed a half-life of 15 h at 80℃, and there was a 60% increase in its activity at 10 mM Ca²⁺ concentration. The activity of the protease was completely inhibited (100%) by phenylmethylsulfonyl fluoride (PMSF); however, the addition of sodium dodecyl sulfate (SDS) resulted in a 20% increase in activity. The enzyme was also stable in various organic solvents and in certain commercial detergents. Furthermore, the enzyme exhibited strong potential for industrial use, particularly as a detergent additive and for facilitating the recovery of silver from X-ray film.

• Journal of Microbiology and Biotechnology
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• v.11 no.4
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• pp.577-584
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• 2001

An antimicrobially active bacterium which was identified as Bacillus brevis, was isolated from kimchi. The antimicrobial activity was found against various Gram-positive and Gram-negative bacteria including some pathogens food-spoilage microorganisms, and some yeast strains. The antimicrobial activity was especially strong against Bacillus anthracis and Shigella dysenteriae. The strong activity was observed during an early stationary phase in the culture when incubated at $37^{\circ}C$ with initial medium pH of 6.8. The antimicrobial activity was found to be stable at $90^{\circ}C$ for 30 min and in the pH range of 3-11, and it was insensitive to organic solvents including acetone, acetonitrile, ethanol, and methanol. Analysis of the bacterocin on tricine-sodium dodecyl sulfate-polyacrylamide gel suggested a molecular mass of approximately 4.5-6.0 kDa. The antimicrobial substance was characterized as a bacteriocin, because of its proteinaceous nature and low molecular weight. The bacteriocin could potentially be used as a food preservative, because of its thermostable property and broad antimicrobial spectrum.

• Journal of Microbiology and Biotechnology
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• v.21 no.1
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• pp.20-27
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• 2011

The purification and characterization of a $Mn^{2+}$-dependent alkaline serine protease produced by Bacillus pumilus TMS55 were investigated. The enzyme was purified in three steps: concentrating the crude enzyme using ammonium sulfate precipitation, followed by gel filtration and cation-exchange chromatography. The purified protease had a molecular mass of approximately 35 kDa, was highly active over a broad pH range of 7.0 to 12.0, and remained stable over a pH range of 7.5 to 11.5. The optimum temperature for the enzyme activity was found to be $60^{\circ}C$. PMSF and AEBSF (1 mM) significantly inhibited the protease activity, indicating that the protease is a serine protease. $Mn^{2+}$ ions enhanced the activity and stability of the enzyme. In addition, the purified protease remained stable with oxidants ($H_2O_2$, 2%) and organic solvents (25%), such as benzene, hexane, and toluene. Therefore, these characteristics of the protease and its dehairing ability indicate its potential for a wide range of commercial applications.

• Applied Biological Chemistry
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• v.31 no.4
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• pp.382-386
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• 1988

Extracellular protein produced by Bacillus sp. $T_2-3$ was characterized for its patterns of sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and sephadex G-100 filtration, spectrum of maximum absorption, composition of amino acid and solubility to solvents. The extracellular protein was composed of two kinds of protein which was little difference in molecular weight about 49,000. Maximum absorbance of the extracellular protein was showed at 230nm and main amino acids of the extracellular protein were aspartic acid, glutamic acid and alanine. Solubility of the extracellular protein was 55.8% in $H_2O$ and 28.4% in 0.4% NaOH.

• Journal of Microbiology and Biotechnology
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• v.16 no.5
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• pp.731-739
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• 2006

A bacterial strain HJ-14 was isolated as a producer of antioxidants from the coast of Jinhae in Korea. The isolate showed 43.4mol% of G+C content, and contained dihydrogenated ubiquinone with Q8 as a major quinone. Chemotaxonomic analysis as well as phylogenetic analysis, based on the 16S rDNA sequence, identified the isolate as a member of Alteromonas macleodii. For antioxidant production, the optimum medium composition was determined to be 3% dextrin, 0.5% ammonium sulfate, and 2-6% sodium chloride. Optimum culture conditions for production of antioxidant materials with strain HJ-14 were at pH 6.0-8.0 and $25-37^{\circ}C$. The chloroform extract of strain HJ-14 broth showed 1.96-17.5-fold higher antioxidant activity than other organic solvents in term of electron donating ability.

• Microbiology and Biotechnology Letters
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• v.24 no.5
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• pp.567-573
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• 1996

Chitinase (EC 3.2.1.14) from culture fluid of Bacillus licheniformis KFB-C14 was purified 66-folds to homogenity in overall yield of 21% by ammonium sulfate fractionation, DEAE-Toyopearl, Butyl-Toyopearl and TSK-Gel HW-55F column chromatography. The enzyme protein had a molecular weight of about 86,000 and was composed of one subunit. The enzyme was significantly stable not only at high temperature but also on treatment with organic solvents and protein denaturants such as SDS, urea and guanidine-HC1. The optimum temperature and pH for reaction was 60$\circ $C and 6.0, respectively. The enzyme activity was inhibited by only Mn$^{2+}$ ion, but not inhibited by EDTA, N- ethylmaleimide and pCMB. The enzyme had high activity with colloidal chitin (V$_{max}$: 421) and commercial chitin (V$_{max}$: 480), but not with typical substrates of exo type chitinase. The thermostable chitinase had an useful reactivity for producing functional chitooligosaccharide, showing the production of (GlcNAc)$_{1}, (GlcNAc)$_{3}$, and (GlcNAc)$_{2}$ as major product.

• Macromolecular Research
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• v.17 no.7
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• pp.483-490
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• 2009

Stable poly(styrene-co-divinylbenzene) [P(St-co-DVB)] micro spheres with narrow size distribution were synthesized in the presence of 2,2'-azobis(2,4-dimethyl valeronitrile) (V-65) and co-initiator in an acetone/water mixture in the precipitation polymerization at $53^{\circ}C$ for 24 h. Potassium peroxodisulfate (KPS), ammonium peroxodisulfate (APS) and sodium peroxodisulfate (NaPS) were used as co-initiators. The optimum ratio of acetone to water for the formation of a narrow distribution of P(St-co-DVB) particles was 49:11 (g/g). The optimum co-initiator compositions for narrow distribution were 9:1 (g/g) for V-65 to KPS, 11:1 for V-65 to APS and 6:1 for V-65 to NaPS. The yield for these compositions was $54{\sim}57%$ and the largest particle size was obtained with the lowest zeta-potential and CV values. From the XPS measurements, the charge density was increased but the zeta potential decreased with increasing sulfur content, implying that the sulfate group provides the electrostatic stabilization on the particle surface. This suggested that the self-crosslinking between styrene and DVB, the electrostatic stabilization of initiators, and the balanced hydrophobic and hydrophilic properties of the solvents are responsible for the formation of stable P(St-co-DVB) spherical particles with narrow size distribution.

• Bulletin of the Korean Chemical Society
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• v.19 no.10
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• pp.1036-1042
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• 1998

The preconcentration and determination of trace elements in water samples were studied by a solvent sublation utilizing dithizonate complexation. After metal dithizonates were formed, trace amounts of cadmium, cobalt, copper and lead were floated and extracted into small volume of a water-immiscible organic solvent on the surface of sample solution and determined in the solvent directly by GF-AAS. Several experimental conditions as formation condition of metal-dithizonate complexes, pH of solution, amount of dithizone, stirring time, the type and amount of surfactants, N2 bubbling rate and so on were optimized for the complete formation and effective flotation of the complexes. And also four kinds of light solvents were compared each other to extract the floated complexes, effectively. After the pH was adjusted to 4.0 with 5 M HNO3, 8.0 mL of 0.05% acetone solution of dithizone was added to 1.00 L water sample. The dithizonate complexes were flotated and extracted into the upper methyl isobutylketone (MIBK) layer by the addition of 2.0 mL 0.2% ethanolic sodium lauryl sulfate solution and with the aid of small nitrogen gas bubbles. And this solvent sublation method was applied to the analysis of real water samples and good results of more than 85% recoveries were obtained in spiked samples.

• Korean Journal of Environmental Agriculture
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• v.30 no.1
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• pp.60-67
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• 2011

BACKGROUND: Because dried herbal medicines have many active ingredients, it is not easy to determine the residue amount after extraction, partition and clean up of pesticides from them. Especially, liquid-liquid partition method is consuming many times and solvents. Macroporous diatomaceous earth(MDE) column was used to replace the separatory funnel for liquid-liquid extraction with dichloromethane to analyze the endosulfan and its metabolite. METHODS AND RESULTS: The residue analysis method using MDE column instead of liquid-liquid partition for determining insecticide endosulfan and its metabolite in 4 dried herbal medicines was developed by GC/MS. As a result, the recovery rates of the pesticides in 4 herbal medicines were ranged from 80.3 to 93.5% for ${\alpha}$-endosulfan, from 81.0 to 100.3% for ${\beta}$-endosulfan and from 80.6 to 95.6% for endosulfan sulfate, respectively. The coefficients of variation for triplicate were ranged from 1.1 to 3.4%. CONCLUSION: The improved methods are more ecofriendly, safer, faster and less laborious than conventional method by KFDA.