• Journal of Life Science
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• v.21 no.1
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• pp.127-133
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• 2011

${\beta}$-Galactosidase was immobilized on chitosan bead by covalent bonding using glutaraldehyde. The characteristics of the immobilized enzyme were investigated. Maximum immobilization yield of 75% was obtained on chitosan bead. Optimum pH and temperature for the immobilized enzyme was 7.0 and $50^{\circ}C$, respectively. The immobilized enzyme showed a broader range of pH and temperature compared to a free one. A mathematical model for the operation of the immobilized enzyme in a packed-bed reactor was established and solved numerically. Under different inlet lactose concentrations and feed flow rate conditions, lactose conversion was measured in a packed-bed reactor. The experimental results of continuous operation in a packed-bed reactor were compared to theoretic results using Michaelis-Menten kinetics with competitive product inhibition and external mass transfer resistance. The model predicted the experimental data with errors less than 5%. Process optimization of continuous operation in a packed-bed reactor was also conducted. In a recirculation packed-bed operation, conversion of lactose was 97% in 3 hours. In a continuous packed-bed operation, the effect of flow rate and initial lactose concentration was investigated. Increasing flow rates and initial lactose concentration decreased the conversion of substrate.

• Microbiology and Biotechnology Letters
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• v.44 no.1
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• pp.62-67
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• 2016

Hydrolytic enzyme activities, including those of ${\beta}$-glucosidase, ${\beta}$-glucuronidase, ${\beta}$-xylosidase, ${\beta}$-galactosidase, ${\beta}$-arabinofuranosidase, ${\beta}$-arabinosidase, and ${\beta}$-arabinopyranosidase, which are useful for bioconversion, were explored in lactic acid bacteria isolated from Korean traditional fermented foods. Nine bacterial strains were selected for the fermentation of green tea extract prepared by supercritical fluid extraction. Changes in the concentrations of catechin, epicatechin, epicatechin gallate, epigallocatechin, and epigallocatechin-3-gallate in green tea extract were investigated after fermentation by the selected lactic acid bacteria strains. The strain Leuconostoc mesenteroides MBE1424, which showed the highest ${\beta}$-glucuronidase enzyme activity among the tested bacterial strains, increased the epigallocatechin content of the green tea extract by 60%. In addition, L. mesenteroides MBE1424 was more resistant than the control strain at high temperature and showed a maximum specific growth rate at $40^{\circ}C$. L. mesenteroides MBE1424 was presumed to have an enzyme system containing ${\beta}$-glucuronidase with utility in the bioconversion of green tea extract.

• Applied Biological Chemistry
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• v.39 no.6
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• pp.437-442
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• 1996

Two strains of Lactobacillus(L.) casfi and one strain of L. Pentosus, which were isolated from pickles, were used to investigate in studing their characteristics of ${\beta}-galactosidase$. The preferable carbon sources and pH of the MRS media for enzyme production from L. casei No.10 was found to be 1.0% lactose and pH 7.5, from L. Pentosus No.63 was 1.0% galactose and pH 7.5, and from L. casei No.36 was 1.0% lactose and pH 6.5, respectively. The maximum enzyme production from each strain was found after 48 hours culture at $30^{\circ}C$ in a medium with preferable carbon source. The optimum reaction temperature with substrate for ${\beta}-galactosidase$ activity was found at $60^{\circ}C$ for all three strains . The stability of enzyme from L. casei No.36 was found to be at $45^{\circ}C$, from L. Pentosus No.63 was found at $55^{\circ}C$. This stability from L. casei No.36 was found at $40^{\circ}C$, but it was reduced to 60% at $55^{\circ}C$. These stabilities of enzymes remained about 90% at $40^{\circ}C$ for all three strains. The optimal pH for enzyme activities was found to be pH 6.5 for all three strains. Enzyme activity remained over 90% for L. casei No.10 at $pH\;5.0{\sim}6.0$, for L. casei No.36 at $pH\;5.0{\sim}8.0$, and for L. pentosus No.63 at $pH\;6.0{\sim}7.0$.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 1996.04a
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• pp.15-15
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• 1996

• Journal of Dairy Science and Biotechnology
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• v.1 no.2
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• pp.24-31
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• 1981

• Proceedings of the Korean Nutrition Society Conference
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• 2001.05a
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• pp.329.2-329
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• 2001

• Journal of Sericultural and Entomological Science
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• v.39 no.1
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• pp.36-43
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• 1997

In order to express the FLP recombinase in B. mori cultured cell line, BmN-4, transient expression system using a heat shock protein gene (hsp70) promoter of Dorosophilla melnogaster was constructed. This vector was designated as pHsSV. Activity strength of the hsp70 promoter was compared with that of immediate early gene (IE-1) and polyhedrin gene of BmNPV employing the E. coli $\beta$-galactosidase gene as a reporter gene. The result showed that the pHs $\beta$-gal plasmid vector expressed the $\beta$-galactosidase at 2nd and 3rd day after the transfer of plasmid DNA into BmN-4 cells, which was similar to that of pIE1 $\beta$-gal vector, but different from that of a recombinant virus, vBm $\beta$-gal. For the construction of FLP recombinase transient expression vector, the FLP recombinase gene was cloned by polymerase chain reaction technique. To express the FLP recombinase, this gene was inserted into pHsSV plasmid vector, under the control of the hsp70 promotor, and tranfected in BmN-4 cells. The expressed FLP recombinase was estimated at 44kDa on a 12.5% SDS-PAGE.

• Journal of Life Science
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• v.24 no.1
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• pp.54-60
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• 2014

Aromatic hydrocarbons are toxic environmental pollutants that are detrimental to the ecosystem and human health. Among them, chlorotoluene and nitrotoluene are toxic to hydrobios and irritate the skin, eyes, and respiratory organs of humans. We herein report the development of recombinant microbial biosensors for cheap and rapid monitoring of chlorotoluene and nitrotoluene compounds. Plasmids were constructed by inserting the xylR regulatory gene for BTEX (benzene, toluene, ethylbenzene, and xylene) degradation into upstream of Po' (the DmpR activator promoter Po with the deletion of its own upstream activating sequences) or Pu (the cognate promoter of XylR)::lacZ (the ${\beta}$-galactosidase gene) and transformed into Escherichia coli $DH5{\alpha}$. In the presence of inducers, the biosensor cells immobilized in agarose developed a red color in 1-2 h due to the hydrolysis of chlorophenol red ${\beta}$-D-galactopyranoside (CPRG), a substrate of ${\beta}$-galactosidase that was expressed by the inducers. Among BTEX, high responses were specifically observed with o-, m-, p-chlorotoluene ($0.1{\mu}M-100 mM$) and o-, m-, p-nitrotoluene (0.1 mM-100 mM). Po' demonstrated higher responses than those with Pu. The biosensors immobilized in agarose showed good stability after 21 days' storage at $4^{\circ}C$, and responses in untreated wastewater spiked with chlorotoluene and nitrotoluene, suggesting they can be used to detect compounds in wastewater.

• BMB Reports
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• v.46 no.3
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• pp.157-162
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• 2013

Human ${\alpha}$-galactosidase A (GLA) has been used in enzyme replacement therapy for patients with Fabry disease. We expressed recombinant GLA from Chinese hamster ovary cells with very high productivity. When compared to an approved GLA (agalsidase beta), its size and charge were found to be smaller and more neutral. These differences resulted from the lack of terminal sialic acids playing essential roles in the serum half-life and proper tissue targeting. Because a simple sialylation reaction was not enough to increase the sialic acid content, a combined reaction using galactosyltransferase, sialyltransferase, and their sugar substrates at the same time was developed and optimized to reduce the incubation time. The product generated by this reaction had nearly the same size, isoelectric points, and sialic acid content as agalsidase beta. Furthermore, it had better in vivo efficacy to degrade the accumulated globotriaosylceramide in target organs of Fabry mice compared to an unmodified version.

• Korean Journal of Microbiology
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• v.52 no.3
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• pp.344-351
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• 2016

A marine bacterium, designated as strain 50C-3, was isolated from a seawater sample collected from the East Sea of South Korea. The strain is a Gram-negative, aerobic, yellow colored polar-flagellated bacterium that grows at $20-50^{\circ}C$ and pH 5.5-8.5. Optimal growth occurred at $40-50^{\circ}C$, at pH 6.5-7.5, and in the presence of 2% (w/v) NaCl. Based on 16S rRNA gene sequence similarity, the isolate was considered to represent a member of the genus Ruegeria. The result of this analysis showed that strain 50C-3 shared 99.4% and 96.98% sequence similarity with Ruegeria intermedia CC-GIMAT-$2^T$ and Ruegeria lacuscaerulensis ITI-$1157^T$, respectively. Furthermore, strain 50C-3 showed clear differences from related strains in terms of several characteristics such as motility, carbon utilization, enzyme production, etc. The DNA G+C content was 66.7 mol%. Chemotaxonomic analysis indicated ubiquinone-10 (Q-10) as the predominant respiratory quinone. Based on phenotypic, chemotaxonomic, and phylogenetic characteristics, the isolate represents a novel variant of the Ruegeria intermedia CC-GIMAT-$2^T$, for which we named Ruegeria sp. 50C-3 (KCTC23890=DSM25519). Strain 50C-3 did not produce cellulase and agarase, but produced alkaline phosphatase, ${\alpha}$-galactosidase, and ${\beta}$-galactosidase. The three enzymes showed stable activities even at $50^{\circ}C$ and thus regarded as thermostable enzymes. Especially, the ${\beta}$-galactosidase activity enhanced by 1.9 times at $50^{\circ}C$ than that at $37^{\circ}C$, which may be very useful for industrial application.