• Journal of Microbiology and Biotechnology
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• v.28 no.12
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• pp.2046-2056
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• 2018

Phospholipase D has great commercial value due to its transphosphatidylation products that can be used in the food and medicine industries. In order to construct a strain for use in the production of PLD, we employed a series of combinatorial strategies to increase PLD expression in Bacillus subtilis WB600. These strategies included screening of signal peptides, selection of different plasmids, and optimization of the sequences of the ribosome-binding site (RBS) and the spacer region. We found that using the signal peptide amyE results in the highest extracellular PLD activity (11.3 U/ml) and in a PLD expression level 5.27-fold higher than when the endogenous signal peptide is used. Furthermore, the strain harboring the recombinant expression plasmid pMA0911-PLD-amyE-his produced PLD with activity enhanced by 69.03% (19.1 U/ml). We then used the online tool \RBS Calculator v2.0 to optimize the sequences of the RBS and the spacer. Using the optimized sequences resulted in an increase in the enzyme activity by about 26.7% (24.2 U/ml). In addition, we found through a transfer experiment that the retention rate of the recombinant plasmid after 5 generations was still 100%. The final product, phosphatidylserine (PS), was successfully detected, with transphosphatidylation selectivity at 74.6%. This is similar to the values for the original producer.

• Microbiology and Biotechnology Letters
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• v.19 no.4
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• pp.348-355
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• 1991

DNA segment encoding $\beta$-1, 4-glucanase of Bacillus subtilis was fused in frame to mouse $\alpha$-amylase signal sequence behind the alcohol dehydrogenase isoenzyme I gene (ADHI) promoter of the yeast expression vector pMS12. To enhance the expression level of the $\beta$glucanase gene in yeast, transcription terminator sequence iso-1-cytochrome c gene (CYCI) was inserted into the recombinant plasmid. The transformants harbouring such recombinant plasmids secreted $\beta$-glucanase into the culture medium. The expresstion level of the $\beta$-glucanase gene was increased about 2-fold caused by inserting the terminator. The amount of the secreted $\beta$-glucanase in culture medium was approximately 60% of the total quantity synthesized.

• Korean Journal of Microbiology
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• v.30 no.6
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• pp.539-545
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• 1992

Recombinant plasmid pPLac15 determined both phosphoenolpyruvate-dependent phosphotransferase uptake of lactose and phospho-$\beta$-galactosidase (Moon et al., 1989). A restriction mapping of the pPLac15 was compiled with several restriction enzymes and a seriese of sub clones into pUC18 was constructed. From an analysis of the proteins produced by Escherichia coli cells of transformants containing each of the recombinant subclone plasmids, it was found that the gene for phospho-$\beta$-galactosidase in pUCI8 was expressed about 1.8-folds in E. coli.

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.261-264
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• 2002

CHO (Chinese hamster ovary) cells were transfected with plasmids containing both cis-acting HRE (hypoxia response element) and CMV-promoter that controls tissue-type plasminogen activator (t-PA). CHO cells with HRE produced 16.2 fold higher t-PA concentration than CHO cells without HRE. It was noted that hypoxia strongly induced CHO cell apoptosis. which resulted in decrease of cell viability and protein production. In this study. by introducing Bcl-2, anti-apoptotic gene, we tried to recover cell viability and increase the protein production. When batch culture of both control cells without transfection of Bcl-2 and cells transfected with Bcl-2 were performed in the absence of CoCl ι hypoxia mimic condition. the cells with Bcl-2 were effected specific cell growth rates, maximum cell density. Immunoblotting assay showed Bcl-2 was recombinant with HRE dependent t- P A expression cassette, and their expression level was depended on hypoxia. By introducing Bcl-2, both cell viability and maximum cell density could be increased.

• Journal of Microbiology and Biotechnology
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• v.14 no.1
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• pp.216-219
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• 2004

The effect of culture temperature on the production of soluble form of B. macerans cyclodextrin glucanotransferase (CGTase) in recombinant E. coli was investigated. E. coli cell was cotransformed with two plasmids (pTCGT1 and pGroll) in which the cgt and groEL/ES genes are under the control of T7 promoter and pzt-1 promoter, respectively. When tetracycline (10 ng/ml) and IPTG (l mM) were added as inducers at the early-exponential phase (2 h) and mid-exponential phase (3h), respectively, the solubilization of the inclusion body CGTase was greatly dependent on the temperature of the culture. At low culture temperature of $25^\circ{C}$, 2- or 3-fold higher activity and specific activity were obtained over $37^\circ{C}$. SDS-PAGE analysis revealed that about 62% of CGTase in the total CGTase protein was found in the soluble fraction by applying overexpression of GroEL/ES chaperone and by cultivation of E. coli at $25^\circ{C}$, whereas 33% of CGTase was detected in the soluble fraction at $37^\circ{C}$. Therefore, the expression of GroEL/ES and cultivation at $25^\circ{C}$ greatly enhanced the soluble production of CGTase in E. coli.

• Korean Journal of Microbiology
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• v.27 no.1
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• pp.21-26
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• 1989

The chromosomal DNA of Klebsiella penumoniae KNF1 was partially digested with HindIII. pBR322 was completely digested with same enzyme with additional alkaline phosphatase treatment. Both DNA samples were ligated and transformed into E. coli KO60. Single coloneis of the transformed cells were isolated on N0free agar media. These colonies were ampicillin-resistant and tetracycline-sensitive. When the plasmids in transformants were cured, nitrogen-fixing activities were lost. Therefore, these transformants harbored recombinant plasmid including nif genes of K. pneumoniae. Nitrogenase activity of transformant was higher than or the same as that of K. pneumoniae KNF1.

• Korean Journal of Microbiology
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• v.28 no.3
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• pp.181-187
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• 1990

STA gene coding glucoamylase was introduced into haploid Saccharomyces cerevisiae SHY3 and polyploid Saccharomyces cerevisiae 54. We constructed the recombinant plasmid by substituting the promoter region of alcohol dehydrogenase isoenzyme I gene for that of STA gene to increase the expression of STA gene and found that the activity of glucoamylase was increased in transformants. The plasmid stability was improved remarkably when we got the STA gene into the plasmid which had centromere. The activity of glucoamylase and transformation frequency of it, however, was decreased because of low copy number. Industrial polyploid strain was transformed with the recombinant plasmid having the $2\mu$ origin of replication and STA gene. It produced more alcohol than host when fermented in liquefied starch media. The industrial strain, however, was not transformed with the autonomously replicating plasmid containing centromere.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.16
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• pp.7205-7210
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• 2015

Background: In this study, influence caused by expression plasmids of connective tissue growth factor (CTGF) and tissue inhibitor of metalloproteinase-1 (TIMP-1) short hairpin RNA (shRNA) on mRNA expression of CTGF,TIMP-1,procol-${\alpha}1$ and PCIII in hepatic tissue with hepatic fibrosis, a precancerous condition, in rats is analyzed. Materials and Methods: To screen and construct shRNA expression plasimid which effectively interferes RNA targets of CTGF and TIMP-1 in rats. 50 cleaning Wistar male rats are allocated randomly at 5 different groups after precancerous fibrosis models and then injection of shRNA expression plasimids. Plasmid psiRNA-GFP-Com (CTGF and TIMP-1 included), psiRNA-GFP-CTGF, psiRNA-GFP-TIMP-1 and psiRNA-DUO-GFPzeo of blank plasmid are injected at group A, B, C and D, respectively, and as model control group that none plasimid is injected at group E. In 2 weeks after last injection, to hepatic tissue at different groups, protein expression of CTGF, TIMP-1, procol-${\alpha}1$ and PC III is tested by immunohistochemical method and,mRNA expression of CTGF,TIMP-1,procol-${\alpha}1$ and PCIII is measured by real-time PCR. One-way ANOVA is used to comparison between-groups. Results: Compared with model group, there is no obvious difference of mRNA expression among CTGF,TIMP-1,procol-${\alpha}1$, PC III and of protein expression among CTGF, TIMP-1, procol-${\alpha}1$, PC III in hepatic tissue at group injected with blank plasmid. Expression quantity of mRNA of CTGF, TIMP-1, procol-${\alpha}1$ and PCIII at group A, B and C decreases, protein expression of CTGF, TIMP-1, procol-${\alpha}1$, PC III in hepatic tissue is lower, where the inhibition of combination RNA interference group (group A) on procol-${\alpha}1$ mRNA transcription and procol-${\alpha}1$ protein expression is superior to that of single interference group (group B and C) (P<0.01 or P<0.05). Conclusions: RNA interference on CTGF and/or TIMP-1 is obviously a inhibiting factor for mRNA and protein expression of CTGF, TIMP-1, procol-${\alpha}1$ and PCIII. Combination RNA interference on genes of CTGF and TIMP-1 is superior to that of single RNA interference, and this could be a contribution for prevention of precancerous condition.

• Journal of Microbiology and Biotechnology
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• v.22 no.9
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• pp.1258-1263
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• 2012

2,3-Butanediol (2,3-BD) is a major metabolite produced by Klebsiella pneumoniae KCTC2242, which is a important chemical with wide applications. Three genes important for 2,3-BD biosynthesis acetolactate decarboxylase (budA), acetolactate synthase (budB), and alcohol dehydrogenase (budC) were identified in K. pneumoniae genomic DNA. With the goal of enhancing 2,3-BD production, these genes were cloned into pUC18K expression vectors containing the lacZ promoter and the kanamycin resistance gene to generate plasmids pSB1-7. The plasmids were then introduced into K. pneumoniae using electroporation. All strains were incubated in flask experiments and 2,3-BD production was increased by 60% in recombinant bacteria harboring pSB04 (budA and budB genes), compared with the parental strain K. pneumoniae KCTC2242. The maximum 2,3-BD production level achieved through fed-batch fermentation with K. pneumoniae SGJSB04 was 101.53 g/l over 40 h with a productivity of 2.54 g/l.h. These results suggest that overexpression of 2,3-BD synthesis-related genes can enhance 2,3-BD production in K. pneumoniae by fermentation.

• Biotechnology and Bioprocess Engineering:BBE
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• v.10 no.1
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• pp.29-33
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• 2005

A DNA vaccine methodology using eukaryote expression vectors to produce immunizing proteins in the vaccinated hosts is a novel approach to the development of vaccine and immuno-therapeutics, and it has achieved considerable success over several infectious diseases and various cancers. To further enhance its efficiency, attempts were made to develop novel plasmid vectors containing multiple immunostimulatory CpG motifs, for rapid and strong immune response. First, a 2.9 kb compact plasmid vector (pVAC), containing CMV promoter, polycloning site, BGH poly(A) terminator, ampicillin resistance gene and pBR322 origin was constructed. A pVAC-hEPO was also constructed, which contained a human erythropoietin gene, for evaluating the transfection efficiency of naked plasmid DNA both in vitro and in vivo. To examine the adjuvant effect of multi-CpG motifs on naked plasmid DNA, 22 and 44 enriched and unmethylated CpG motifs were introduced into pVAC to generate pVAC-ISS1 and pVAC-ISS2, respectively. $100{\mu}g$ of pSecTagB, pVAC, pVAC-ISS1 or pVAC-ISS2 were each injected intramuscularly into the tibilias anterior muscle of Balb/c mice. The level of interleukin-6 induced in the mice injected with pVAC-ISS1 and pVAC-ISS2 were significantly elevated after 12 hours, which were almost 2 and 2.5 times higher than that in the mice injected with pSecTagB, respectively. These results suggest that DNA vaccine plasmids with enriched CpG motifs can induce rapid secretion of interleukin-6 by lymphocytes. In conclusion, these vectors can contribute to the development of adjuvant-free DNA vaccinations against infectious diseases and various cancers.