• Journal of Microbiology and Biotechnology
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• v.23 no.10
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• pp.1422-1427
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• 2013

Scutellaria baicalensis (SB), a traditional herb with high pharmacological value, contains more than 10% flavone by weight. To improve the biological activity of flavones in SB, we aimed to enhance the bioconversion of baicalin (BG) to baicalein (B) and wogonoside (WG) to wogonin (W) in SB during fermentation using beta-glucuronidase produced from Lactobacillus brevis RO1. After activation, L. brevis RO1 was cultured in milk containing SB root extract with various carbon or nitrogen sources at $37^{\circ}C$ for 72 h. During fermentation, the growth patterns of L. brevis RO1 and changes in the flavone content were assessed using thin-layer chromatography and high-performance liquid chromatography. After 72 h of fermentation, the concentrations of B and W in the control group increased by only 0.15 and 0.12 mM, respectively, whereas they increased by 0.57 and 0.24 mM in the fish peptone group. The production of B and W was enhanced by the addition of 0.4% fish peptone, which not only improved the growth of L. brevis RO1 (p < 0.001) but also enhanced the bioconversion of flavones. In conclusion, the bioconversion of flavones in SB may provide a potential application for the enhancement of the functional components in SB.

• Environmental Engineering Research
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• v.17 no.1
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• pp.3-8
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• 2012

A scaled-up bioconversion of fishmeal wastewater (FMW) into liquid fertilizer was performed five times in a $1m^3$ reactor in order to examine the feasibility of commercialization. The importance of aeration was marked. Analyses indicated that dissolved oxygen (DO) level was closely related to the value of oxidation-reduction potential (ORP) and it was crucial to achieve high-quality liquid fertilizer. When pure oxygen was supplied through four diffusers into the reactor, DO levels and ORP values were maintained over 1.2 mg/L and 0.2 mV, respectively all the time during 52 hr of bioconversion. The pH changed from 6.8 to 5.9. The average removal percentages of chemical oxygen demand ($COD_{Cr}$) and total nitrogen (TN) were 75.0% and 71.6%, respectively. Compared to the result acquired in a 5-L reactor, bioconversion of FMW into liquid fertilizer was achieved in a shorter time under the same removal percentages of $COD_{Cr}$ and TN. The 52-hr culture of inoculated FMW was phytotoxic-free and it possessed comparable fertilizing ability to a liquid fertilizer made from the fish waste in hydroponic culture with amino acid contents of 5.93 g/ 100 g sample. From all the above results, transferring lab-scale data to large-scale production appeared to be successful. As a result, the commercialization of a liquid fertilizer made from FMW was feasible.

• Korean Journal of Microbiology
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• v.53 no.4
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• pp.323-325
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• 2017

Pectobacterium carotovorum subsp. actinidiae KKH3 is an Enterobacteriaceae bacterial pathogen that infects kiwi plants, causing canker-like symptoms that pose a threat to the kiwifruit industry. Because the strain was originally isolated from woody plants and possesses numerous plant cell wall-degrading enzymes, this draft genome report provides insight into possible bioconversion applications, as well as a better understanding of this important plant pathogen.

• Microbiology and Biotechnology Letters
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• v.18 no.1
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• pp.49-55
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• 1990

The bioconversion of D, L-20aminothiazoline-4-carboxylic acid (D, L-ATC) to L-cysteine was investigated. After the intracelluar enzyme of a Pseudomonas species was inducibly formed by addition of D, L-ATC in the middle of culture, the cells were isolated and treated with sonication to prepare the crude enzyme solution. The results indicated that the cysteine was produced only in the form of L-isomer from D,L-ATC and its production could be enhanced several tens times by addition of managanese ions which were required as a cofactor in this enzymatic reaction. Bedies, this reaction suffered from the feedback inhibition of L-cysteine. On the other hand, since L-cysteine-decomposing enzyme coexisted in the crude enzyme solution, most of the L-cyseine formed disappeared in the absence of its inhibitor. However, hydroxylamine was found to be a potent inhibitor which could successfully prevent the decomposition of L-cyseine.

• Journal of Applied Biological Chemistry
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• v.62 no.2
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• pp.111-122
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• 2019

The mulberry tree (Morus alba L.) has been traditionally used in Chinese medicine to treat inflammatory diseases. We investigated the effects of bioconversion on different components of the mulberry tree, and determined changes in the physiological activities. Ethyl acetate-soluble fractions of five different segments (fruit, Mori Fructus; leaf, Mori Folium; twig, Mori Ramulus; root, Mori Cortex; and mistletoe, Loranthi Ramulus) of the mulberry tree show enhanced anti-oxidant effects in the 2,2-diphenyl-1-picrylhydrazyl, and 2,2'-azinobis-(3-ethylvenzothiazoline-6-sulfonic acid) assays, and enhanced anti-inflammatory effects of lipopolysaccharide (LPS)-stimulated nitric oxide (NO) production in RAW 264.7 macrophages, after being treated with a crude enzyme extract from Aspergillus kawachii, in the following order of activity: Mori Folium>Mori Cortex>Mori Ramulus>Mori Fructus>Loranthi Ramulus. Ethyl acetate- soluble fraction of mulberry leaves (Mori Folium) that underwent bioconversion was most effective, and was devoid of any cytotoxicity. The fraction was also effective against mRNA expression of LPS-induced pro-inflammatory cytokines, such as inducible nitric oxide synthase, cyclooxygenase-2, tumor necrosis $factor-{\alpha}$, $interleukin-1{\beta}$, and interleukin-6. In addition, the fraction was effective in LPS-induced phosphorylation of mitogen-activated protein kinases and IKK, and $I{\kappa}B$ degradation, followed by translocation of the nuclear $factor-{\kappa}B$ from the cytoplasm to the nucleus. Thus, bioconversion increased the anti-oxidative and anti-inflammatory activities of the mulberry leaf.

• Mycobiology
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• v.42 no.3
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• pp.256-261
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• 2014

A ${\beta}$-glucosidase producing yeast strain was isolated from Korean traditional rice wine. Based on the sequence of the YCL008c gene and analysis of the fatty acid composition, the isolate was identified as Saccharomyces cerevisiae strain HJ-014. S. cerevisiae HJ-014 produced ginsenoside Rd, $F_2$, and compound K from the ethanol extract of red ginseng. The production was increased by shaking culture, where the bioconversion efficiency was increased 2-fold compared to standing culture. The production of ginsenoside $F_2$ and compound K was time-dependent and thought to proceed by the transformation pathway of: red ginseng extract ${\rightarrow}Rd{\rightarrow}F_2{\rightarrow}$ compound K. The optimum incubation time and concentration of red ginseng extract for the production of compound K was 96 hr and 4.5% (w/v), respectively.

• Journal of Microbiology and Biotechnology
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• v.27 no.5
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• pp.869-877
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• 2017

Lactic acid bacteria (LAB) are used as fermentation starters in vegetable and dairy products and influence the pH and flavors of foods. For many centuries, LAB have been used to manufacture fermented foods; therefore, they are generally regarded as safe. LAB produce various substances, such as lactic acid, ${\beta}$-glucosidase, and ${\beta}$-galactosidase, making them useful as fermentation starters. Existing functional substances have been assessed as fermentation substrates for better component bioavailability or other functions. Representative materials that were bioconverted using LAB have been reported and include minor ginsenosides, ${\gamma}$-aminobutyric acid, equol, aglycones, bioactive isoflavones, genistein, and daidzein, among others. Fermentation mainly involves polyphenol and polysaccharide substrates and is conducted using bacterial strains such as Streptococcus thermophilus, Lactobacillus plantarum, and Bifidobacterium sp. In this review, we summarize recent studies of bioconversion using LAB and discuss future directions for this field.

• KSBB Journal
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• v.27 no.2
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• pp.127-130
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• 2012

In this study, the effects of pH, temperature, IPTG concentration and substrate (MSG) concentration on gamma-aminobutyric acid (GABA) production in engineered Escherichia coli were investigated. Glutamate decarboxylase and glutamate/GABA antiporter were overexpressed in GABA aminotransferase knock-out strain for GABA production. The result of optimization study showed the GABA bioconversion was optimized at pH 3.5, $30^{\circ}C$, 0.5 mM IPTG, 10 g/L MSG. At this condition, 5.23 g/L of final GABA concentration of was achieved from 10 g/L of MSG, which corresponded to a GABA yield of 85.77%.

• The Microorganisms and Industry
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• v.17 no.2
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• pp.12-17
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• 1991

미생물학적 물질변환에 대해서는 인류 초기에서부터 효모를 이용하여 빵, 유제품, 알코올, 음료 등의 생산에 이용하여 왔으며, 주로 농업분야 또는 식품 분야에 국한되어 왔다. 1862년 Pasteur에 의해 bacterium xylinum의 순수 배양균주를 사용하여 알코올로부터 초산을 만드는데 응용한 것이 본격적인 시발점으로 보아 무방하겠다. 그 후 acetobacter aceti에 의한 포도당으로부터 gluconic acid 생산과 acetobacter sp.에서의 sorbitol로부터 sorbose 생산 등이 이루어졌고 정통적인 유기합성 방법에 의해 쉽게 만들 수 없는 반응들에 응용되기 시작하였다. 인류 초기의 혼합배양에 의한 물질변환에의 응용과는 달리 순수배양으로 미생물, 식물세포, 혹은 정제된 효소들에 의해 반응이 이루어지게 되었고 순수한 특정 물질에 대한 새로운 순수물질로의 선별적인 수식도 가능해지게 되었다. 특히 발효와 bioconversion의 차이는 racemates의 분리, 비슷한 반응성을 갖는 여러 기들로부터 특정기능을 갖는 기만의 선별적인 수식, 입체 이성체(chiral center)의 제작, 특정 비활성화된 탄소의 기능 등이 bioconversion에서만 수행할 수 있는 독특한 영역으로서 정밀화학분야, energy 분야, 환경오염분야에서의 특히 미래의 관심 기술로 대두되고 있다.

• The Microorganisms and Industry
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• v.17 no.2
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• pp.28-30
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• 1991

APM의 화학적, 효소적 합성방법의 선택은 각기의 장단점을 비교 검토한 후 결정해야 할 문제로서, 수율, 공정의 효율성, 작업환경, 경제성 등의 여러 요인이 영향을 줄 수 있으나, 최근의 연구동향 및 산업적 생산의 추이는 효소를 이용한 bioconversion process에 의한 방식으로 나아가는 듯 하다. 결론적으로 bioconversion process에 의한 APM의 생산은 반응매질로써 유기용매의 사용이 불가피하므로 효소의 안정성을 증가시켜 장기간 사용할 수 있는 신기술의 개발이 필요하며 기존의 고정화 기술은 그 좋은 예가 될 수 있다. 또한 보호기의 도입과 제거과정이 보다 용이해야하며 더 나아가서 보호기의 부착없이도 반응을 가능케하는, 기질에 대한 특이성이 높은 새로운 효소(예를 들어 exopeptidase를 사용하면 기질에 보호기를 붙일 필요가 없으므로 화학적 방법에 비해 훨씬 유리하다)의 screening이 절실하다. 아울러 유기용매로 인한 효소의 deactivation mechanism의 규명과 반응기 운전 system의 개발이 요구된다 하겠다.