• 한국식품과학회지
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• 제29권5호
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• pp.1021-1027
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• 1997

Dicyma sp. YCH-37이 생산하는 효모세포벽 용해효소의 성질을 검토한 결과, 각종 환원제와 금속이온에 대체로 안정하였고, guanidine-HCl을 제외한 여러 화학수식제에 대해서도 안정하였다. 배양시간, 전처리 및 배양조건에 따른 영향을 검토한 결과, 정지기 및 사멸기에 있는 효모보다는 대수증식기의 효모, 그리고 생효모에 비해 열처리된 효모가 더 잘 용균되었다. Butanol, acetone 등의 유기용매로 처리된 효모가 그렇지 않은 효모보다 용균도가 좋았으며, 0.5 M ammonium sulfate가 함유된 Yeast extract-Malt extract 배지에서 생육한 효모, 그리고 진탕배양한 효모보다 정치배양한 효모가 용균효소에 의해 더 잘 용균되었다. SDS, Triton X-100, ${\beta}-mercaptoethanol$, potassium chloride, sodium sulfite 등의 화학수식제를 효소반응액에 첨가하였을 때 기질 효모는 더 잘 용균되었다.

• Journal of Microbiology and Biotechnology
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• 제11권4호
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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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• 제21권1호
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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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• 제31권4호
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• pp.382-386
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• 1988

Chemically defined medium을 사용하여 Bacillus sp. $T_2-3$으로 균체외단백질을 생산한 후 이들의 각종 물리화학적 성질을 조사 하였다. 균체외단백질은 전기영동과 gel 여과 결과로 분자량이 약 49,000이 되는 비슷한 2종의 단백질로 구성되어 있었다. 최대흡수파장은 230nm 부근이었으며 aspartic acid를 가장 많이 함유하고 있었다. 또한 균체외단백질의 물에대한 용해도는 55.8%, 0.4% NaOH에 대한 용해도는 28.4%로 albumin과 glutelin계통의 단백질로 생각되었다.

• Journal of Microbiology and Biotechnology
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• 제16권5호
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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.

• 한국미생물·생명공학회지
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• 제24권5호
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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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• 제17권7호
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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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• 제19권10호
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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.

• 한국환경농학회지
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• 제30권1호
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• pp.60-67
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• 2011

현재 식품의약품안전청에서 고시하고 있는 한약재 중 잔류 농약 분석법에 따라 강활, 박하, 천궁 및 황기 시료 중 endosulfan과 그 분해산물인 endosulfan sulfate를 분석한 결과 많은 간섭물질의 등장과 낮은 회수율 등의 문제점을 확인하였다. 이에 고시된 시험법의 액-액 분배 과정을 대신하여 MDE column을 적용하여 ${\alpha}$-endosulfan 80.3 ~ 93.5%, ${\beta}$-endosulfan 81.0 ~ 100.3%, endosulfan sulfate 80.6 ~ 95.6%의 회수율과 1.1 ~ 3.4%의 변이계수(CV)를 얻었으며 이러한 결과는 잔류농약 분석기준을 만족하였다. MDE column의 사용으로 액-액 분배 과정을 대신하면서 발암가능 물질인 dichloromethane 사용을 배제할 수 있어 분석자의 안전성 향상, 노동력 및 전처리 시간의 절감, 발생되는 폐액 감소, 액-액 분배시 emulsion 현상의 해소, 분석자간의 재현성 양호 등의 이점도 얻을 수 있었다.

• 공업화학
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• 제16권5호
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• pp.677-683
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• 2005

AEO계 비이온 계면활성제를 주체로 한 세정제 시스템에서 탄화수소 용제가 단일상의 마이크로에멀젼 형성 및 세정력에 미치는 영향을 살펴보았다. 용제로 사용한 포화탄화수소의 사슬 길이가 길어질수록 마이크로에멀젼을 형성하는 온도 영역이 넓어졌으며, $35{\sim}60^{\circ}C$의 온도 조건에서 첨가한 보조계면활성제 조성에 상관없이 단일상의 ${\mu}E$이 존재하는 것을 확인할 수 있었다. 특히 본 실험에서 사용한 탄화수소 중에서 사슬 길이가 가장 큰 헥사데칸을 용제로 사용할 경우, 보조계면활성제 이소프로판올을 첨가하지 않은 경우에도 단일상의 O/W ${\mu}E$이 넓은 온도 영역에 걸쳐서 존재하였다. 상평형 실험을 통하여 선정한 단일상의 마이크로에멀젼을 주체로 한 후보 세정제 시료들은 $40^{\circ}C$에서 abietic acid에 대한 우수한 세정력을 나타내는 것을 세정 실험을 통하여 확인할 수 있었다.