• Journal of Life Science
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• v.29 no.7
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• pp.755-761
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• 2019

Kojic acid (KA) is produced by Aspergillus oryzae-sort of like mushrooms, which is commonly called as koji in Japan. KA is used as a chelation agent and a preservative preventing oxidative browning of fruits. KA also shows antibacterial and antifungal properties. Because KA stops the production of melanin by inhibiting tyrosinase in the biosynthetic pathway from tyrosine to melanin in skin, it has been applied as a skin lightening ingredient in cosmetics. Since some animal studies have shown that high amounts of KA had side effects such as in liver, kidney, reproductive, cardiovascular, gastrointestinal, respiratory, brain, and nervous system, more efficient KA derivatives are needed to be developed in order to safely apply as a skin lightening ingredient. A series of KA derivatives via conjugated with triazole by click reaction were synthesized and their in vitro tyrosinase inhibitory activities were evaluated. Most of all KA derivatives have shown in moderate tyrosinase inhibitory activities. In case of KA-hybrid compound, 1~3 have shown tyrosinase inhibitory activities about 50~10,000 times more effective tyrosinase inhibitor compared to KA itself. Specifically, the $IC_{50}$ value of KA-hybrid compound, 2 was $0.0044{\pm}0.74{\mu}M$ against tyrosinase. It is about 10,000 times more effective tyrosinase inhibitor compared to KA itself ($IC_{50}=45.2{\pm}4.6{\mu}M$).

• Journal of Microbiology and Biotechnology
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• v.4 no.1
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• pp.1-6
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• 1994

Continuous culture was carried out with a recombinant Escherichia coli W3110/pCR185, which encodes trp-operon enzymes when the temperature is shifted from $37^{circ}C\;t;42^{\circ}C$. Under derepressed condition of $42^{\circ}C$. plasmlid stability and gene expression were analysed as function of the dilution rate. The stability of plasmid increased with the dilution rate, but maximal levels of gene expression (tryptophan concentration) and plasmid DNA content were obtained at the lowest dilution rate, $0.075\;hr^{-1}$. The plasmid instability, observed at low dilution rates, could be explained by the unbalanced biosynthetic state of the recombinant cell harboring a high copy number of plasmid.

• Journal of Microbiology and Biotechnology
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• v.30 no.1
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• pp.1-10
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• 2020

FK506, also known as tacrolimus, is a clinically important immunosuppressant drug and has promising therapeutic potentials owing to its antifungal, neuroprotective, and neuroregenerative activities. To generate various FK506 derivatives, the structure of FK506 has been modified by chemical methods or biosynthetic pathway engineering. Herein, we describe the mode of the antifungal action of FK506 and the structure-activity relationship of FK506 derivatives in the context of immunosuppressive and antifungal activities. In addition, we discuss the neurotrophic mechanism of FK506 known to date, along with the neurotrophic FK506 derivatives with significantly reduced immunosuppressive activity. This review suggests the possibility to generate novel FK506 derivatives as antifungal as well as neuroregenerative/neuroprotective agents.

• Journal of Microbiology and Biotechnology
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• v.16 no.5
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• pp.799-803
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• 2006

It was reported that an accumulation of Sadenosyl-L-methionine increases production of actinorhodin in Streptomyces lividans and induces antibiotic biosynthetic genes. We also obtained the same result in Streptomyces coelicolor A3(2). Therefore, in order to identify proteins changed by the addition of S-adenosyl-L-methionine in S. coelicolor A3(2), LC/MS/MS analyses were carried out. Thirteen proteins that were not observed in the control were found.

• YAKHAK HOEJI
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• v.34 no.6
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• pp.447-456
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• 1990

Various methods are available for the production of L-threonine. The microbial production of L-threonine has been achieved by breeding L-threonine analog-resistant auxotrophic mutants of various bacteria. The enzymatic production of L-threonine has been demonstrated by use of threonine metabolic enzymes such as threonine deaminase, threonine aldolase, or threonine dehydrogenase complex. Threonine synthesis from glycine and ethanol seems to be catalyzed by the enzymes Methanol dehydrogenase(MDH) and Serine hydroxymethyltransferase(SHMT), which was also found to catalyze the aldol condensation of glycine with acetaldehyde. The improved production of L-threonine has been achieved by amplifying the genes for the L-threonine biosynthetic enzymes using recombinant DNA techniques.

• The Korea Genome Conference
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• 2002.08a
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• pp.49.1-49.1
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• 2002

• The Journal of Natural Sciences
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• v.17 no.1
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• pp.103-111
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• 2006

Regulation of invertase biosynthesis was studied with the E. coil harboring recombinant plasmid, pYC17. Biosynthesis of invertase in the recombinant E. coil was effectively induced in the presence of 30mM of sucrose for 3h. Glucose also repressed the invertase induction in the recombinant E. coil at 10 mM, lower than that of parent strain (30 mM).

• Journal of Microbiology and Biotechnology
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• v.6 no.6
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• pp.425-431
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• 1996

The enzymatic characteristics of Alcaligenes latus were investigated by measuring the variations of various enzyme activities related to biosynthesis and degradation of poly-${\beta}$-hydroxybutyrate (PHB) during cultivation. All PHB biosynthetic enzymes, ${\beta}$-ketothiolase, acetoacetyl-CoA reductase, and PHB synthase, were activated gradually at the PHB accumulation stage, and the PHB synthase showed the highest value among three enzymes. This indicates that the rate of PHB biosynthesis is mainly controlled by either ${\beta}$-ketothiolase or acetoacetyl-CoA reductase rather than PHB synthase. The enzymatic activities related to the degradation of PHB were also measured, and the degradation of PHB was controlled by the activity of PHB depolymerase. The effect of supplements of metabolic regulators, citrate and tyrosine, was also investigated, and the activity of glucose-6-phosphate dehydrogenase was increased by metabolic regulators, especially by tyrosine. The activities of ${\beta}$-ketothiolase and acetoacetyl-CoA reductase were also activated by citrate and tyrosine, while the activity of PHB depolymerase was depressed. The increased rate and yield of PHB biosynthesis by metabolic regulators may be due to the increment of acetyl-CoA concentration either by the repression of the TCA cycle by citrate through product inhibition or by the activation of sucrose metabolism by the supplemented tyrosine.

• Journal of Microbiology and Biotechnology
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• v.24 no.9
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• pp.1226-1231
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• 2014

The rare actinomycete Pseudonocardia autotrophica was previously shown to produce a solubility-improved toxicity-reduced novel polyene compound named $\underline{N}ystatin$-like $\underline{P}seudonocardia$ $\underline{P}olyene$ (NPP). The low productivity of NPP in P. autotrophica implies that its biosynthetic pathway is tightly regulated. In this study, $wblA_{pau}$ was isolated and identified as a novel negative regulatory gene for NPP production in P. autotrophica, which showed approximately 49% amino acid identity with a global antibiotic down-regulatory gene, wblA, identified from various Streptomycetes species. Although no significant difference in NPP production was observed between P. autotrophica harboring empty vector and the S. coelicolor wblA under its native promoter, approximately 12% less NPP was produced in P. autotrophica expressing the wblA gene under the strong constitutive $ermE^*$ promoter. Furthermore, disruption of the $wblA_{pau}$ gene from P. autotrophica resulted in an approximately 80% increase in NPP productivity. These results strongly suggest that identification and inactivation of the global antibiotic down-regulatory gene wblA ortholog are a critical strategy for improving secondary metabolite overproduction in not only Streptomyces but also non-Streptomyces rare actinomycete species.

• Journal of Microbiology and Biotechnology
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• v.16 no.6
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• pp.974-978
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• 2006

The cytochrome P450 monooxygenase from the pikromycin biosynthetic gene cluster in Streptomyces venezuelae, known as PikC, was observed to hydroxylate the unnatural substrate indole to indigo. Furthermore, the site-directed mutagenesis of PikC monooxygenase led to the mutant enzyme F171Q, in which Phe171 was altered to Gln, with enhanced activity for the hydroxylation of indole. From enzyme kinetic studies, F171Q showed an approximately five-fold higher catalytic efficiency compared with the wild-type PikC. Therefore, these results demonstrate the promising application of P450s originating from Streptomyces, normally involved in polyketide biosynthesis, to generate a diverse array of other industrially useful compounds.