• Biotechnology and Bioprocess Engineering:BBE
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• v.10 no.4
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• pp.304-308
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• 2005

The response of IPTG induction was investigated through the monitoring of the alkali consumption rate and buffer capacity during the cultivation of recombinant E. coli BL21 (DE3) harboring the plasmid pRSET-LacZ under the control of lac promoter. The rate of alkali consumption increased along with cell growth, but declined suddenly after approximately 0.2 h of IPTG induction. The buffer capacity also declined after 0.9 h of IPTG induction. The profile of buffer capacity seems to correlate with the level of acetate production. The IPTG response was monitored only when introduced into the mid-exponential phase of bacterial cell growth. The minimum concentration of IPTG for induction, which was found out to be 0.1 mM, can also be monitored on-line and in-situ. Therefore, the on-line monitoring of alkali consumption rate and buffer capacity can be an indicator of the metabolic shift initiated by IPTG supplement, as well as for the physiological state of cell growth.

• Microbiology and Biotechnology Letters
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• v.44 no.4
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• pp.497-503
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• 2016

This study aimed to optimize the culture conditions of recombinant Escherichia coli expressing otsBA using crude glycerol for the enhanced production of trehalose. The effects of culture temperature and isopropyl ${\beta}$-D-1-thiogalactopyranoside (IPTG)-induction were investigated. Trehalose production and cell growth were highest when cells were cultured at $37^{\circ}C$ and induced with IPTG. The concentrations of IPTG, validamycin A, and NaCl were optimized using Box-Behnken design. Statistical analyses of the experimental data revealed that the concentrations of IPTG and NaCl had significant effects on trehalose production, but that of validamycin A did not. Contour plot analysis and model calculation showed that the highest amount of trehalose could be produced at 298 mM NaCl and 0.1 mM IPTG. Under these optimal conditions, the optical density at 600 nm and trehalose production were $5.4{\pm}0.2$ and $304{\pm}15mg/l$, respectively.

• Journal of Microbiology and Biotechnology
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• v.30 no.8
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• pp.1124-1131
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• 2020

Techniques used for the regulation of gene expression facilitate studies of gene function and treatment of diseases via gene therapy. Many tools have been developed for the regulation of gene expression in mammalian cells. The Lac operon system induced with isopropyl β-D-1-thiogalactopyranoside (IPTG) is one of the employed inducible systems. IPTG mimics the molecular structure of allolactose and has a strong affinity for the corresponding repressor. IPTG is known to rapidly penetrate into mammalian cells and exhibits low toxicity. In the present study, we developed a new inducible expression system that could regulate the expression of genes in mammalian cells using IPTG. Here we confirm that unlike other vector systems based on the Lac operon, this expression system allows regulation of gene expression with lactose in the mammalian cells upon transfection. The co-treatment with IPTG and lactose could improve the regulatory efficiency of the specific target gene expression. The regulation of gene expression with lactose has several benefits. Lactose is safe in humans as compared to other chemical substances and is easily available, making this technique very cost-effective.

• KSBB Journal
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• v.21 no.4
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• pp.236-240
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• 2006

IPTG induction caused a sudden drop of alkali consumption rate during cultivation of a recombinant E. coli with ${\beta}$-galactosidase structural gene under T7 promoter on a plasmid. A series of batch cultivations showed the positive correlation of the decrease of alkali consumption and the level of expression. However, repeated IPTG induction did not cause any variation of alkali consumption rate. Supplementation of medium even at stationary phase enhanced the level of ${\beta}$-galactosidase expression. These results suggests that the drop of alkali consumption rate by IPTG induction represents the rate of expression.

• Korean Journal Plant Pathology
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• v.13 no.4
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• pp.248-254
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• 1997

Expression vector (pGEX-Tu) for the coat protein (CP) gene of turnip mosaic virus Ca strain (TuMV-Ca) was constructed by incorporation of TuMV CP gene into pGEX-KG vector which had ${\beta}$-galactosidase gene and IPTG (isopropylthio-${\beta}$-D-galactoside) induction site. The results of ELISA and western hybridization indicated that optimal condition of the expression were when IPTG and western hybridization indicated that optimal condition of the expression were when IPTG induction was carried out on YTA medium with ampicillin in 2 hours after the E. coli seed inoculation ($A_{595}$=0.1/ml). TuMV CP gene was expressed with GST (Glutathion S-Transferase) gene fusion system, and the size of fusion protein was estimated to be 59kDa, for TuMV CP was 33 kDa and GST was 26 kDa.

• Fisheries and Aquatic Sciences
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• v.8 no.3
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• pp.118-121
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• 2005

Arylsulfatase cloned from a marine bacterium, Pseudoalteromonas carrageenovora, was over-expressed in Escherichia coli. Most of the recombinant arylsulfatase was found in the cell lysate with induction up to $10{\mu}M$ IPTG. However, enzyme activity was observed both in the culture supernatant and cell lysate by induction with IPTG concentration of $50-5,000{\mu}M$. Most of the recombinant enzyme was localized in the periplasmic space with $10{\mu}M$ IPTG induction, while half of the enzyme was distributed in the periplasmic space with $50{\mu}M$ IPTG induction. Cell growth and arylsulfatase activity did not change with the induction time, and the level of recombinant arylsulfatase expression was maintained at 4-5 U/mL after 6 to 14 hr of culture.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.12
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• pp.1751-1757
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• 2004

Recombinant heterologous proteins can be produced as insoluble aggregates partially or perfectly inactive in Escherichia coli. One of the strateges to improve the solubility of recombinant proteins is fusion with a partner that is excellent in producing soluble fusion proteins. To improve the production of soluble $\beta$-galactosidase, the gene of Thermus thermophilus KNOUC112 $\beta$-galactosidase (KNOUC112 $\beta$-gal) was fused with thioredoxin gene, and optimization of its expression in E. coli TOP10 was performed. KNOUC112 $\beta$-gal in pET-5b was isolated out, fused with thioredoxin gene in pThioHis C, and transformed to E. coli TOP10. The $\beta$-galactosidase fused with thioredoxin was produced in E. coli TOP10 as dimer and trimer. The productivity of fusion $\beta$ -galactosidase expressed via pThioHis C at 37$^{\circ}C$ was about 5 times higher than that of unfused $\beta$-galactosidase expressed via pET-5b at 37$^{\circ}C$. Inclusion body of $\beta$-galactosidase was formed highly, regardless of the induction by IPTG when KNOUC112 $\beta$ -gal was expressed via pET-5b at 37$^{\circ}C$. Fusion $\beta$ -galactosidase expressed at 37$^{\circ}C$ via pThioHis C without the induction by IPTG was soluble, but the induction by IPTG promoted the formation of inclusion body. Lowering the incubation temperature for the expression of fusion gene under 25$^{\circ}C$ prevented the formation of inclusion body, optimally at 25$^{\circ}C$. 0.07 mM of IPTG was sufficient for the soluble expression of fusion gene at 25$^{\circ}C$. The soluble production of Thermus thermophilus KNOUC112 $\beta$-galactosidase could be increased about 10 times by fusion with thioredoxin, and optimization of incubation temperature and IPTG concentration for induction.

• Journal of Microbiology and Biotechnology
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• v.14 no.6
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• pp.1310-1317
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• 2004

The extracellular production of 5-aminolevulinic acid (ALA) by recombinant E. coli BL21 harboring a fusion gene hemA was investigated in a fermenter. For this purpose, the effects of various physiological factors, such as isopropylthio­$\beta$-D-galactopyranoside (IPTG) concentrations and the time of induction, on enzyme activity were studied. Optimum concentrations of glycine and succinic acid were found to be 30 mM and 90 mM, respectively. When the cells were permitted to grow for 2 h prior to the addition of 0.1 mM IPTG, the activity of ALA synthase was higher than when IPTG was initially added. A 36-fold increase in the activity was observed with only 0.1 mM IPTG added. The pH of the medium also influenced the ALA synthase activity with the maximal activity occurring at pH 6.5. In recombinant E. coli extracts, the repeated addition of glycine and D-glucose increased the production of ALA and the inhibited intracellular ALA dehydratase activity, with up to 32 mM ALA being produced in the cultivation.

• Journal of Microbiology and Biotechnology
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• v.1 no.4
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• pp.274-280
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• 1991

Effects of IPTG induction on cell growth and production of ${\beta}$-galactosidase-preS2 fusion protein (${\beta}$gal-preS2) were studied in a defined medium using a recombinant Escherichia coli JM109/pCMHB30. IPTG was added (0.2 mM) to induce the cloned-gene expression in the early-, mid-, and late-log growth phases. The most serious decreases in growth rate and plasmid stability were observed for the induction in the early-log growth phase. The expression level of ${\beta}$gal-preS2 attained by the induction in the mid-log phase was about 0.51 mg fusion protein/mg total cellular protein, which was 2- and 5-fold improvement over the levels obtained with the inductions in the early- and late-log phases. Formation of acidic byproducts including acetate and pyruvate showed different profiles during the fermentation period for each cases of induction; pyruvate was the major byproduct for the induction in the early-log phase while acetate production became more significant for the cases of inductions in the mid- and late-log phases.

• BMB Reports
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• v.30 no.1
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• pp.80-84
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• 1997

The synthesis and secretion of human angiogenin in E. coli by the natural leader sequence has been studied. We constructed a recombinant plasmid containing human angiogenin cDNA which encompassed all the coding region including leader sequence required for secretion. The recombinant plasmid was introduced into a suitable E. coli host. The angiogenin was detected in the culture medium and periplasm upon the induction of gene expression. The molecular weight of the secreted angiogenin was identical to that of authentic angiogenin purfied from human plasma when estimated by SDS-PAGE and immunoblotting. showing that the natural leader sequence was recognized and processed by the secretion machinery of E. coli. The angiogenin concentration in the culture medium reached a maximum within 2 h when expressed at $37^{\circ}C$ with 0.02~2 mM IPTG. In contrast, the expression level increased gradually over time up to 11 h at $23^{\circ}C$ with 0.002~2 mM IPTG and at $37^{\circ}C$ with 0.002 mM IPTG.