• Analytical Science and Technology
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• v.7 no.1
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• pp.25-31
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• 1994

As for analytes which did not represent the differences of the selectivity on the stationary and mobile phase, secondary chemical equilibrium theory was applied to study pH effects on the separation of alkylphenols. Mobile phase was consisted of an aqueous sodium carbonate-bicarbonate buffer and acetonitrile. The maximum selectivity for adjacent peak pairs was predicted from those values of $k^{\prime}_{HA}/k^{\prime}_{A-}$ and ${\Delta}pK$. The optimum pH determined by this method was 11.18 pH and solvent selectivity were considered at the same time to invoke the full range of selectivity effects possible for separations. Quaternary mixture composed of methanol, acetonitrile, tetrahydrofuran and water was adjusted to optimum pH 11.18. As the statistical simplex technique of an overlapping resolution map (ORM) was used to predict the optimized solvent system. The optimum solvent, which gives complete separation of alkylphenols, was determined as follws MeOH : ACN : THF = 14.4 : 81.8 : 2.8.

• Microbiology and Biotechnology Letters
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• v.22 no.5
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• pp.522-530
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• 1994

Bacteriocin-producing lactic acid bacteria, Lactococcus sp. HY 449, was isolated from dairy products. Using response surface methodology, the various concentrations of medium compo- nents (tryptone, glucose, yeast extract, tween 80, and initial pH) were tested to find the optimum conditions for maximum bacteriocin production and growth of Lactococcus sp. HY 449. Central composite design was used to control the concentrations of medium components in the experiment. Bacteriocin production and cell growth of Lactococcus sp. HY 449 were most affected by glucose and yeast extract. Estimated optimum growth conditions of Lactococcus sp. HY 449 were as follows; tryptone 1.08%, glucose 1.129%, yeast extract 0.674%, tween 80 0.11%, and initial pH 7.19. Also estimated optimum conditions for bacteriocin production were tryptone 0.937%, glucose 1.108%, yeast extract 0.163%, tween 80 0.09%, and initial pH 6.98.

• KSBB Journal
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• v.18 no.6
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• pp.490-494
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• 2003

For the production of antifungal compound, strain B-1 was used as a strong producing strain among bacteria isolated from various soil samples. The optimum medium for the production of antifungal compound was PDB (potato starch 0.4%, dextrose 2％, pH5.1). The optimum conditions for the production of antifungal compound didn't affect on the carbon and nitrogen sources. The produced compound showed broad antimicrobial activity to the tested strains such as five fungi and four bacteria. The optimum pH and temperature of the production antifungal compound were pH 5.0 and 28$^{\circ}C$, respectively. Ether extrct (1$\mu\textrm{g}$/${\mu}\ell$) of culture broth was confirmed inhibitory zone by the thin layer chromatography and plate assay. The antimicrobial compound was unstabled after heat (121$^{\circ}C$) trsatment. Strain B-1 was mass cultured in a 5-liter tormentor, containing 3 liters of PDB medium at 28$^{\circ}C$, pH 5.0, 120 (pm with aeration (1L/min).

• Journal of the Korean Chemical Society
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• v.48 no.6
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• pp.654-658
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• 2004

• KSBB Journal
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• v.16 no.2
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• pp.207-211
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• 2001

Statistical experimental design methods were employed to select the cultivation factors influencing latic acid production during the fermentation of kitchen refuses. Working volume and pH swings were identified as the main factors affecting lactic acid production. Optimum pH swing was pH 7.8 and working volume was 125 mL in a 250 mL flask. Under optimum condition, lactic acid was produced at 21.8 g/L, which was 6.2 times higher than produced during uncontrolled fermentation.

• Journal of Life Science
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• v.10 no.2
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• pp.210-217
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• 2000

A kinetic profile of the catalytic domain of stromelysin-1 (SCD) using the fluorescent peptide substrate has been determined by the stopped-flow technique. The pH profile has a pH optimum of about 5.5 with an extended shoulder above pH 7. Three pKa values, 5.0, 5.7, and 9.8 are found for the free enzyme state and two pH independent Kcat/Km values of 4.1$\times$104 M-1 s-1 and 1.4$\times$104 M-1 s-1 at low and high pH, respectively. The profile is quite different in shape with other MMP family which has been reported, having broad pH optimum with two pKa values. The substrate specificity of SCD towards fluorescent heptapeptide substrates has been also examined by thin layer chromatography. The cleavage sites of the substrates have been identified using reverse-phase HPLC method.SCD cleaves Dns-PLA↓L↓WAR and Dns-PLA↓L↓FAR at two positions. However, the Dns-PLA↓LRAR, Dns-PLE↓LFAR, adn Dns-PLSar↓LFAR are cleaved exclusively at one bond. The double cleavages of Dns-PLALWAR and Dns-PLALFAR by SCD are in marked contrast to the close structurally related matrilysin. A notable feature of SCD catalysis agrees with the structural data that the S1' pocket of SCD is deeper than that of matriysin. The differences observed between SCD and matrilysin may form the basis of understanding the structural relationships and substrate specificities of the MMP family in vivo.

• Journal of Microbiology and Biotechnology
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• v.25 no.6
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• pp.930-935
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• 2015

A phytase gene was identified in a publicly available metagenome derived from subsurface groundwater, which was deduced to encode for a protein of the histidine acid phosphatase (HAP) family. The nucleotide sequence of the phytase gene was chemically synthesized and cloned, in order to further overexpress the phytase in Escherichia coli. Purified protein of the recombinant phytase demonstrated an activity for phytic acid of 298 ± 17 µmol P/min/mg, at the pH optimum of 2.0 with the temperature of 37℃. Interestingly, the pH optimum of this phytase is much lower in comparison with most HAP phytases known to date. It suggests that the phytase could possess improved adaptability to the low pH condition caused by the gastric acid in livestock and poultry stomachs.

• Food Science and Preservation
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• v.22 no.2
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• pp.256-260
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• 2015

This study investigated the optimum pH condition for the efficient extraction of protein from Gastrodia elata Blume. Five extraction pH values (8, 9, 10, 11, and 12) and three precipitation pH values (2, 4, and 6) were used. The protein content, browning degree, and recovery yield of the protein obtained under each pH condition were determined. Most of the G. elata Blume was made up of carbohydrates, and its protein content was also high. The amount of the extracted protein increased according to the increase in the extraction pH, but did not significantly differ between pH 8 and pH 9. The browning degree of the protein significantly increased as the extraction pH increased. The greatest amount of protein was precipitated at pH 4, the recovery yield of which was also the highest. As a result, it was found that the combination of extraction pH 9 and precipitation pH 4, which resulted in a 38.7% recovery yield and a low browning degree, is the optimum condition for the efficient extraction of protein from G. elata Blume.

• Journal of Microbiology and Biotechnology
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• v.17 no.5
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• pp.769-773
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• 2007

With the aim to produce ascorbic acid-2-phosphate(AsA-2-P) from L-ascorbic acid(AsA, Vitamin C), nine bacteria conferring the ability to transform AsA to AsA-2-P were isolated from soil samples alongside known strains from culture collections. Most isolates were classified to the genus Brevundimonas by 16S phylogenetic analysis. Among them, Brevundimonas diminuta KACC 10306 was selected as the experimental strain because of its the highest productivity of AsA-2-P. The optimum set of conditions for the AsA-2-P production from AsA using resting cells as the source of the enzyme was also investigated. The optimum cultivation time was 16 h and the cell concentration was 120g/l(wet weight). The optimum concentrations of AsA and pyrophosphate were 550mM and 450mM, respectively. The most effective buffer was 50mM sodium formate. The optimum pH was 4.5 and temperature was $40^{\circ}C$. Under the above conditions, 27.5g/l of AsA-2-P was produced from AsA after 36 h of incubation, which corresponded to a 19.7% conversion efficiency based on the initial concentration of AsA.

• The Korean Journal of Food And Nutrition
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• v.9 no.4
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• pp.447-451
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• 1996

Lytic activities of the egg white lysozyme from Korea-native Ogol fowl against the alkalophilic and thermophilic Bacillus sp. TA-11 were investigated and compared. Lytic activity of the Ogol fowl lysozyme for Bacillus sp. TA-11 was the highest for the cell of post-logarithm phase and optimum concentration of the lysozyme was 0.25%, Optimum reaction pH and temperature were 4.5 and 35$^{\circ}C$, respectively. Lytic activity of egg white lysozyme from fowl for Bacillus sp. TA-11 was the highest for the cell of stationary phase and optimum concentration of the lysozyme was 0.5%. Optimum reaction pH and temperature were 5.5 and 4$0^{\circ}C$, respectively.