• Journal of Plant Biotechnology
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• v.30 no.3
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• pp.301-305
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• 2003

The effects of inorganic nitrogen sources such as KNO$_3$ and NH$_4$ NO$_3$ on cell growth and production of chlorogenic acid and eleutheroside E derivative were investigated in 5L bioreactor cultures of Eleutherococcus senticosus. The cell growth in the 1/2MS medium containing 15mMKNO$_{3}$. The fresh weight of cells harvested from bioreactor was affected by the concentration ratio of NO$_3$$^{[-10]}$ and NH$_4$$^{+}$ in culture medium. At the viewpoint of secondary metabolite production, the production of chlorogenic acid was affected by the concentration of NH$_4$$^{+}$ in the culture medium, but not by the total concentration of nitrogen sources in the culture medium. Futhermore, eleutheroside E derivative production was also affected by the concentration ratio of NO$_3$$^{[-10]}$ and NH$_4$$^{+}$ in the culture medium. Base on those results, it is suggested that cell growth and production of secondary metabolite(chlorogenic acid and eleutheroside E derivative) could be manipulated by controlling the total concentration of nitrogen sources and the concentration ratio of NO$_3$$^{[-10]}$ and NH$_4$$^{+}$ in the culture medium. medium.

• Journal of Microbiology and Biotechnology
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• v.23 no.12
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• pp.1737-1746
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• 2013

IbMYB1, a transcription factor (TF) for R2R3-type MYB TFs, is a key regulator of anthocyanin biosynthesis during storage of sweet potatoes. Anthocyanins provide important antioxidants of nutritional value to humans, and also protect plants from oxidative stress. This study aimed to increase transgenic potatoes' (Solanum tuberosum cv. LongShu No.3) tolerance to environmental stress and enhance their nutritional value. Transgenic potato plants expressing IbMYB1 genes under the control of an oxidative stress-inducible peroxidase (SWPA2) promoter (referred to as SM plants) were successfully generated through Agrobacterium-mediated transformation. Two representative transgenic SM5 and SM12 lines were evaluated for enhanced tolerance to salinity, UV-B rays, and drought conditions. Following treatment of 100 mM NaCl, seedlings of SM5 and SM12 lines showed less root damage and more shoot growth than control lines expressing only an empty vector. Transgenic potato plants in pots treated with 400 mM NaCl showed high amounts of secondary metabolites, including phenols, anthocyanins, and flavonoids, compared with control plants. After treatment of 400 mM NaCl, transgenic potato plants also showed high DDPH radical scavenging activity and high PS II photochemical efficiency compared with the control line. Furthermore, following treatment of NaCl, UV-B, and drought stress, the expression levels of IbMYB1 and several structural genes in the flavonoid biosynthesis such as CHS, DFR, and ANS in transgenic plants were found to be correlated with plant phenotype. The results suggest that enhanced IbMYB1 expression affects secondary metabolism, which leads to improved tolerance ability in transgenic potatoes.

• Journal of Microbiology and Biotechnology
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• v.31 no.1
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• pp.8-15
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• 2021

More and more available fungal genome sequence data reveal a large amount of secondary metabolite (SM) biosynthetic 'dark matter' to be discovered. Heterogeneous expression is one of the most effective approaches to exploit these novel natural products, but it is limited by having to clone entire biosynthetic gene clusters (BGCs) without errors. So far, few effective technologies have been developed to manipulate the specific large DNA fragments in filamentous fungi. Here, we developed a fungal BGC-capturing system based on CRISPR/Cas9 cleavage in vitro. In our system, Cas9 protein was purified and CRISPR guide sequences in combination with in vivo yeast assembly were rationally designed. Using targeted cleavages of plasmid DNAs with linear (8.5 kb) or circular (8.5 kb and 28 kb) states, we were able to cleave the plasmids precisely, demonstrating the high efficiency of this system. Furthermore, we successfully captured the entire Nrc gene cluster from the genomic DNA of Neosartorya fischeri. Our results provide an easy and efficient approach to manipulate fungal genomic DNA based on the in vitro application of Cas9 endonuclease. Our methodology will lay a foundation for capturing entire groups of BGCs in filamentous fungi and accelerate fungal SMs mining.

• Journal of Microbiology and Biotechnology
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• v.31 no.4
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• pp.601-609
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• 2021

Erythrobacter species are extensively studied marine bacteria that produce various carotenoids. Due to their photoheterotrophic ability, it has been suggested that they play a crucial role in marine ecosystems. It is essential to identify the genome sequence and the genes of the species to predict their role in the marine ecosystem. In this study, we report the complete genome sequence of the marine bacterium Erythrobacter sp. 3-20A1M. The genome size was 3.1 Mbp and its GC content was 64.8%. In total, 2998 genetic features were annotated, of which 2882 were annotated as functional coding genes. Using the genetic information of Erythrobacter sp. 3-20A1M, we performed pan-genome analysis with other Erythrobacter species. This revealed highly conserved secondary metabolite biosynthesis-related COG functions across Erythrobacter species. Through subsequent secondary metabolite biosynthetic gene cluster prediction and KEGG analysis, the carotenoid biosynthetic pathway was proven conserved in all Erythrobacter species, except for the spheroidene and spirilloxanthin pathways, which are only found in photosynthetic Erythrobacter species. The presence of virulence genes, especially the plant-algae cell wall degrading genes, revealed that Erythrobacter sp. 3-20A1M is a potential marine plant-algae scavenger.

• Journal of Microbiology and Biotechnology
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• v.17 no.12
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• pp.1909-1921
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• 2007

Significant progress has recently been made concerning the engineering of deoxysugar biosynthesis. The biosynthetic gene clusters of several deoxysugars from various polyketides and aminoglycosides-producing microorganisms have been cloned and studied. This review introduces the biosynthetic pathways of several deoxysugars and the generation of novel hybrid macrolide antibiotics via the coexpression of deoxysugar biosynthetic gene cassettes and the substrate-flexible glycosyltransferases in a host organism as well as the production of TDP-deoxysugar derivatives via one-pot enzymatic reactions with the identified enzymes. These recent developments in the engineering of deoxysugars biosynthesis may pave the way to create novel secondary metabolites with potential biological activities.

• Journal of Microbiology and Biotechnology
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• v.18 no.10
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• pp.1655-1658
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• 2008

Cyanobacteria, blue-green algae, are a rich source of bioactive secondary metabolites with many potential applications. The ubiquitin-proteasome proteolytic system plays an important role in selective protein degradation and regulates cellular events including apoptosis. Cancer cells are more sensitive to the proapoptotic effects of proteasome inhibition than normal cells. Thus, proteasome inhibitors can be potential anticancer agents. Cyanobacteria have been shown to be a rich source of highly effective inhibitors of proteases. A proteasome inhibitor was screened from an extract of the culture of Scytonema hofmanni on the basis of its inhibitory activity, which led to the isolation of nostodione A with an $IC_{50}$ value of 50${\mu}M$. Its structure was determined by spectroscopic methods such as $^{1}H$-NMR and ESI-MS spectral analyses.

• Microbiology and Biotechnology Letters
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• v.39 no.1
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• pp.20-28
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• 2011

Phylogenetic analysis of two cellulase genes, xynB1 and bglA2, and the groEL1 gene from 34 Sorangium cellulosum strains isolated in Korea suggested that there are at least five subgroups in S. cellulosum, which is the most proficient producer of secondary metabolites among myxobacteria. This analysis also revealed diversity among the isolated S. cellulosum. It appeared that at least 30 out of 34 strains are different each other.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.19
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• pp.8007-8018
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• 2014

Cervical cancer is the most common gynecologic malignancy worldwide and development of new therapeutic strategies and anticancer agents is an urgent priority. Plants have remained an important source in the search for novel cytotoxic compounds and several polyphenolic flavonoids possess antitumor properties. In this review article, data about potential anticarcinogenic activity of common natural flavonoids on various human cervical cancer cell lines are compiled and analyzed showing perspectives for the use of these secondary metabolites in the treatment of cervical carcinoma as well as in the development of novel chemotherapeutic drugs. Such anticancer effects of flavonoids seem to differentially depend on the cellular type and origin of cervical carcinoma creating possibilities for specific targeting in the future. Besides the cytotoxic activity per se, several flavonoids can also contribute to the increase in efficacy of conventional therapies rendering tumor cells more sensitive to standard chemotherapeutics and irradiation. Although the current knowledge is still rather scarce and further studies are certainly needed, it is clear that natural flavonoids may have a great potential to benefit cervical cancer patients.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.185-188
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• 2001

We have developed a synthetic method for dTDP-4-keto-6-deoxy-D-glucose with four enzyme system. We have used crude extracts from cultures of Escherichia coli BL21 strains harboring plasmids containing different sources. dTDP-4-keto-6-deoxy-D-glucose was synthesized by the combination of thymidine-monophosphate kinase, acetate kinase, dTDP-glucose synthase and dTDP-D-glucose 4,6-dehydratase in a batch system, starting the reaction with dTMP. The enzymatic synthesis strategy allowed a dTMP conversion with a 95%.

• Microbiology and Biotechnology Letters
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• v.21 no.4
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• pp.322-328
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• 1993

During the screening of antifungal compounds from microbial secondary metabolites to control phytophthora blight of red pepper caused by Phytophthora capsici, a soil isolate, strain 38D10 was selected. Based on taxonomic studies, this strain was identified as Streptomyces neyagawaensis. The antifungal compound was purified from culture broth by HP-20 column chromatography, ethyl acetate extraction, silica gel column chromatography, HPLC and identified as concanamycin B by UV. $^1H$-NMR, $^{13}C$-NMR, SIMS analysis. Concanamycin B has strong antifungal activity against some phytopathogenic fungi but not antivacterial activity and preventive value were 50% and 100% at 125ppm and 250ppm in pot assay.