• Biotechnology and Bioprocess Engineering:BBE
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• v.8 no.6
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• pp.322-330
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• 2003

The unicellular green alga Haematococcus pluvialis has recently attracted great inter-est due to its large amounts of ketocarotenoid astaxanthin, 3,3'-dihydroxy-${\beta}$,${\beta}$-carotene-4,4'-dione, widely used commercially as a source of pigment for aquaculture. In the life cycle of H. pluvialis, astaxanthin biosynthesis is associated with a remarkable morphological change from green motile vegetative cells into red immotile cyst cells as the resting stage. In recent years we have studied this morphological process from two aspects: defining conditions governing astaxanthin biosynthesis and questioning the possible function of astaxanthin in protecting algal cells against environmental stress. Astaxanthin accumulation in cysts was induced by a variety of environmental conditions of oxidative stress caused by reactive oxygen species, intense light, drought, high salinity, and high temperature. In the adaptation to stress, abscisic acid induced by reactive oxygen species, would function as a hormone in algal morphogenesis from veget ative to cyst cells. Furthermore, measurements of both in vitro and in vivo antioxidative activities of astaxanthin clearly demonstrated that tolerance to excessive reactive oxygen species is greater in astaxanthin-rich cysts than in astaxanthin-poor cysts or astaxanthin-less vegetative cells. Therefore, reactive oxygen species are involved in the regulation of both algal morph O-genesis and carotenogenesis, and the accumulated astaxanthin in cysts can function as a protective agent against oxidative stress damage. In this study, the physiological roles of astaxanthin in stress response and cell protection are reviewed.

• Microbiology and Biotechnology Letters
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• v.33 no.1
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• pp.16-23
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• 2005

In order to develop a new microbial fungicide using endophytic bacteria for the control of anthracnoses occurring on various crops, a total of 260 bacterial strains were isolated from fresh tissues of 5 plant species. After they were cultured in broth medium, their antifungal activities were tested for in vivo antifungal activity against cucumber anthracnose caused by Colletotrichum orbiculare. As the results, liquid cultures of 28 strains showed potent antifungal activities more than $90\%$ against cucumber anthracnose. At 3-fold dilutions of liquid cultures, 18 strains inhibited the development of cucumber anthracnose of more than $70\%$. They were further tested for in vivo antifungal activity against red pepper anthracnose caused by C. coccodes and in vitro antifungal activity against C. acutatum, a fungal agent causing red pepper anthracnose. Among 18 strains, a bacterial strain EB215 isolated from cucumber roots displayed the most potent antifungal activity against Colletotrichum species. It was identified as Burkholderia cepacia based on its physiological and biochemical characteristics, Biolog test and 16S rDNA gene sequence. It also controlled effectively the development of rice blast (Magnaporthe grisea), rice sheath blight (Corticium sasaki), tomato gray mold (Botrytis cinerea), and tomato late blight (Phytophthora infestans). Studies on the characterization of antifungal substances produced by B. cepacia EB215 are in progress.

• Journal of Ginseng Research
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• v.37 no.1
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• pp.100-107
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• 2013

This study examined the effect of fermented ginseng (FG) on memory impairment and ${\beta}$-amyloid ($A{\beta}$) reduction in models of Alzheimer's disease (AD) in vitro and in vivo. FG extract was prepared by steaming and fermenting ginseng. In vitro assessment measured soluble $A{\beta}42$ levels in HeLa cells, which stably express the Swedish mutant form of amyloid precursor protein. After 8 h incubation with the FG extract, the level of soluble $A{\beta}42$ was reduced. For behavioral assessments, the passive avoidance test was used for the scopolamine-injected ICR mouse model, and the Morris water maze was used for a transgenic (TG) mouse model, which exhibits impaired memory function and increased $A{\beta}42$ level in the brain. FG extract was treated for 2 wk or 4 mo on ICR and TG mice, respectively. FG extract treatment resulted in a significant recovery of memory function in both animal models. Brain soluble $A{\beta}42$ levels measured from the cerebral cortex of TG mice were significantly reduced by the FG extract treatment. These findings suggest that FG extract can protect the brain from increased levels of $A{\beta}42$ protein, which results in enhanced behavioral memory function, thus, suggesting that FG extract may be an effective preventive or treatment for AD.

• Journal of Microbiology and Biotechnology
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• v.33 no.8
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• pp.1030-1038
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• 2023

Lactiplantibacillus plantarum, previously named Lactobacillus plantarum, is a facultative, homofermentative lactic acid bacterium widely distributed in nature. Several Lpb. plantarum strains have been demonstrated to possess good probiotic properties, and Lpb. plantarum HOM3204 is a potential probiotic strain isolated from homemade pickled cabbage plants. In this study, whole-genome sequencing was performed to acquire genetic information and predict the function of HOM3204, which has a circular chromosome of 3,232,697 bp and two plasmids of 48,573 and 17,060 bp, respectively. Moreover, various oxidative stress-related genes were identified in the strain, and its antioxidant activity was evaluated in vitro and in vivo. Compared to reference strains, the intracellular cell-free extracts of Lpb. plantarum HOM3204 at a dose of 10¹⁰ colony-forming units (CFU)/ml in vitro exhibited stronger antioxidant properties, such as total antioxidant activity, 2,2-diphenyl-1-picrylhydrazyl radical scavenging rate, superoxide dismutase activity, and glutathione (GSH) content. Daily administration of 10⁹ CFU Lpb. plantarum HOM3204 for 45 days significantly improved the antioxidant function by increasing the glutathione peroxidase activity in the whole blood and GSH concentration in the livers of D-galactose-induced aging mice. These results suggest that Lpb. plantarum HOM3204 can potentially be used as a food ingredient with good antioxidant properties.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.55.2-55.2
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• 2012

Intensive theoretical and experimental studies have been carried out at Korean Institute of Science and Technology (KIST) on controlling the bio absorbing rate of the Mg alloys with high mechanical strength through tailoring of electrochemical potential. Key technology for retarding the corrosion of the Mg alloys is to equalize the corrosion potentials of the constituent phases in the alloys, which prevented the formation of Galvanic circuit between the constituent phases resulting in remarkable reduction of corrosion rate. By thermodynamic consideration, the possible phases of a given alloy system were identified and their work functions, which are related to their corrosion potentials, were calculated by the first principle calculation. The designed alloys, of which the constituent phases have similar work function, were fabricated by clean melting and extrusion system. The newly developed Mg alloys named as KISTUI-MG showed much lower corrosion rate as well as higher strength than previously developed Mg alloys. Biocompatibility and feasibility of the Mg alloys as orthopedic implant materials were evaluated by in vitro cell viability test, in vitro degradation test of mechanical strength during bio-corrosion, in vivo implantation and continuous observation of the implant during in vivo absorbing procedures. Moreover, the cells attached on the Mg alloys was observed using cryo-FIB (focused ion beam) system without the distortion of cell morphology and its organ through the removal of drying steps essential for the preparation of normal SEM/TEM samples. Our Mg alloys showed excellent biocompatibility satisfying the regulations required for biomedical application without evident hydrogen evolution when it implanted into the muscle, inter spine disk, as well as condyle bone of rat and well contact interface with bone tissue when it was implanted into rat condyle.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.3
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• pp.251-258
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• 2016

A rhizobacterium LPN-2, which showed strong antifungal activity and auxin producing ability, was isolated from a farmland in North Gyeongsang Province, South Korea. Based on analysis of the 16S rDNA sequence, strain LPN-2 was identified as a novel strain of Burkholderia and was designated as Burkholderia sp. LPN-2. In vitro experiments showed that the isolated stain LPN-2 significantly produced auxin within 48 hr incubation. In order to check for PGPR function we performed in vivo growth promoting test in different crops, including mung bean, pea and cabbage. Application of Burkholderia sp. LPN-2 showed dramatic growth promoting effect on all the tested plants. We also confirmed siderophore and cellulase productions by Burkholderia sp. LPN-2 using CAS blue agar and CMC plate test. Further treatment with LPN-2 and the crude culture broth was effective in suppressing anthracnose in vitro test and also reduced incidence and severity of anthracnose in apple and pepper. Taken together, we conclude that Burkholderia sp. LPN-2 might be used as organic fertilizer for effective crop production in organic farming.

• BMB Reports
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• v.38 no.5
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• pp.577-583
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• 2005

Subtilisin QK, which is newly identified as a fibrinolytic enzyme from Bacillus subtilis QK02, has the ability of preventing nitrotyrosine formation in bovine serum albumin induced by nitrite, hydrogen peroxide and hemoglobin in vitro verified by ELISA, Western-blot and spectrophotometer assay. Subtilisin QK also attenuates the fluorescence emission spectra of bovine serum albumin in the course of oxidation caused by nitrite, hydrogen peroxide and hemoglobin. Furthermore, subtilisin QK could suppress the transformation of oxy-hemoglobin to met-hemoglobin caused by sodium nitrite, but not the heat-treated subtilisn QK. Compared with some other fibrinolytic enzymes and inactivated subtilisin QK treated by phenylmethylsulfonylfluoride, the ability of inhibiting met-hemoglobin formation of subtilisin QK reveals that the anti-oxidative ability of subtilisin QK is not concerned with its fibrinolytic function. Additionally, nitrotyrosine formation in proteins from brain, heart, liver, kidney, and muscle of mice that is intramuscular injected the mixture of nitrite, hydrogen peroxide and hemoglobin is attenuated by subtilisin QK. Subtilisin QK can also protect Human umbilical vein endothelial cell (ECV-304) from the damage caused by nitrite and hydrogen peroxide.

• Microbiology and Biotechnology Letters
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• v.24 no.3
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• pp.304-310
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• 1996

For a probiotic yoghurt it is desirable to utilize lactic acid bacteria with a high survival rate and beneficial function to human beings. We have examined a variety of lactic acid bacteria to assess the acid and bile tolerance and antibiotic resistance. In addition, an in vitro culture experiment was performed to evaluate their ability to reduce cholesterol levels in the growth medium. Thirteen strains were selected from in vitro cholesterol assays and fed to Sprague-Dawley rats with a high-cholesterol diet. Among the 13 strains tested, 8 strains were shown to reduce serum cholesterol levels significantly after 24 days of administration in vivo. Rats were fed lyophilized yoghurt powder fermented with a combination of 3 selected strains: Bifidobacterium infantis AM-220, Lactobacillus AM-245, and Styeptococcus MA-1. The levels of total cholesterol and low density lipoprotein were significantly lower (p$\leq$0.05) in rats fed the yoghurt powder compared with control group. These studies suggest that yoghurt fermented with appropriately selected lactic acid bacteria may have a anticholesterolemic effect.

• Development and Reproduction
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• v.21 no.2
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• pp.167-180
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• 2017

Human adult stem cells have widely been examined for their clinical application including their wound healing effect in vivo. To function as therapeutic cells, however, cells must represent the ability of directed migration in response to signals. This study aimed to investigate the mechanism of platelet-derived growth factor (PDGF)-induced migration of the human abdominal adipose-derived stem cells (hADSCs) in vitro. A general matrix metalloproteinase (MMP) inhibitor or a MMP2 inhibitor significantly inhibited the PDGF-induced migration. PDGF treatment exhibited greater mRNA level and denser protein level of MMP1. The conditioned medium of PDGF-treated cells showed a caseinolytic activity of MMP1. Transfection of cells with siRNA against MMP1 significantly inhibited MMP1 expression, its caseinolytic activity, and cell migration following PDGF treatment. Phosphatidylinositol 3-kinase (PI3K) inhibitor reduced the migration by about 50% without affecting ERK and MLC proteins. Rho-associated protein kinase inhibitor mostly abolished the migration and MLC proteins. The results suggest that PDGF might signal hADSCs through PI3K, and MMP1 activity could play an important role in this PDGF-induced migration in vitro.

• Journal of Microbiology and Biotechnology
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• v.13 no.6
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• pp.841-845
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• 2003

In order for engineered tissues to find clinical utility, the engineered tissues must function appropriately. However, smooth muscle (SM) tissues engineered in vitro with a conventional tissue engineering technique may not exhibit contractile functions, because smooth muscle cells (SMCs) cultured in vitro typically revert from a contractile, differentiated phenotype to a synthetic, nondifferentiated phenotype and lose their ability to contract. SMCs in vivo typically reside in mechanically dynamic environments. We hypothesized that cyclic mechanical stretch induces the features of SMCs in in vitro engineered tissues to be similar to those of SMCs in native tissues. To test the hypothesis, aortic SMCs were seeded onto elastic, three-dimensional scaffolds and cultured in vitro under a cyclic mechanical stretching condition for 4 weeks. A significant cell alignment in a direction parallel to the cyclic stretching direction was found in the SM tissues exposed to cyclic stretching. The cellular alignment and alignment direction were consistent with those of native vascular SM tissues, in which SMCs in vivo align in the radial direction (parallel to stretching direction). In control tissues (SM tissues engineered without stretching), cells randomly aligned. The expression of SM ${\alpha}-actin$ and SM myosin heavy chain, phenotypic markers of SMCs in a contractile state, was upregulated in the stretched tissues by 2.5- and 2.0-fold, respectively, compared to SMCs in the control tissues. The cellular features of alignment and contractile phenotype of SMCs in the SM tissues engineered under a mechanically dynamic environment could allow the engineered SM tissues to exhibit contractile functions.