• IMMUNE NETWORK
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• v.23 no.1
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• pp.6.1-6.24
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• 2023

Intestinal microorganisms interact with various immune cells and are involved in gut homeostasis and immune regulation. Although many studies have discussed the roles of the microorganisms themselves, interest in the effector function of their metabolites is increasing. The metabolic processes of these molecules provide important clues to the existence and function of gut microbes. The interrelationship between metabolites and T lymphocytes in particular plays a significant role in adaptive immune functions. Our current review focuses on 3 groups of metabolites: short-chain fatty acids, bile acids metabolites, and polyamines. We collated the findings of several studies on the transformation and production of these metabolites by gut microbes and explained their immunological roles. Specifically, we summarized the reports on changes in mucosal immune homeostasis represented by the Tregs and Th17 cells balance. The relationship between specific metabolites and diseases was also analyzed through latest studies. Thus, this review highlights microbial metabolites as the hidden treasure having potential diagnostic markers and therapeutic targets through a comprehensive understanding of the gut-immune interaction.

• KSBB Journal
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• v.14 no.2
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• pp.205-211
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• 1999

We investigated optimal conditions for the microbial transformation of $\gamma$-butyrobetaine into L-carnitine by using Achromobacter cycloclast ATCC 21921. When the cells were cultivated in the medium containing $\gamma$-butyrobetaine as the sole carbon source for both cell growth and L-carnitine production, the maximum L-carnitine production was 2.9 g/L and the conversion yield from $\gamma$-butyrobetaine to L-carnitine was as low as 30.9 mol%. In order to enhance the L-carnitine production and the conversion yield, various carbon sources were added to the $\gamma$-butyronetaine containing basal medium. In the medium supplemented with glycerol, L-carnitine production was as high as 4.6 g/L and the conversion yield was 88.2 mol%, showing a significant improvement in L-carnitine synthesis compared to those in the medium without glycerol. We also examined the additional effect of quaternary ammonium compounds such as betaine and choline, which are similar in structure to $\gamma$-butyrobetaine and L-carnitien. It was observed that in the presence of those quaternary ammonium compounds, both the L-carnitine production rate and the conversion yield increased. In addition, we found that cell growth was inhibited by a $\gamma$-butyrobetaine concentration of more than 3%, while L-carnitine production was efficient at the $\gamma$-butyrobetaine concentration of 2-3%. By cultivating the cells in the optimal medium containing glycerol and choline, we obtained an L-carnitine concentration of 7.2 g/L with the conversion yield of 98.7 mol% in 4 days.

• Journal of Microbiology and Biotechnology
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• v.28 no.7
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• pp.1217-1224
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• 2018

Seaweeds produce antioxidants to counteract environmental stresses, and these antioxidant genes are regarded as important defense strategies for marine algae. In this study, the expression of Pyropia yezoensis (Bangiales, Rhodophyta) ascorbate peroxidase (PyAPX) and manganese-superoxide dismutase (PyMnSOD) was examined by qRT-PCR in P. yezoensis blades under abiotic stress conditions. Furthermore, the functional relevance of these genes was explored by overexpressing them in Chlamydomonas. A comparison of the different expression levels of PyAPX and PyMnSOD after exposure to each stress revealed that both genes were induced by high salt and UVB exposure, being increased approximately 3-fold after 12 h. The expression of the PyAPX and PyMnSOD genes also increased following exposure to $H_2O_2$. When these two genes were overexpressed in Chlamydomonas, the cells had a higher growth rate than control cells under conditions of hydrogen peroxide-induced oxidative stress, increased salinity, and UV exposure. These data suggest that Chlamydomonas is a suitable model for studying the function of stress genes, and that PyAPX and PyMnSOD genes are involved in the adaptation and defense against stresses that alter metabolism.

• Journal of Microbiology and Biotechnology
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• v.22 no.5
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• pp.684-689
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• 2012

In the present study, an efficient mercury-tolerant bacterial strain (RS-5) was isolated from heavy-metalcontaminated industrial effluent. Under shake flask conditions, 97% of the supplemented mercuric chloride was sequestered by the biomass of RS-5 grown in a tryptone soy broth. The sequestered mercuric ions were transformed inside the bacterial cells, as an XRD analysis of the biomass confirmed the formation of mercurous chloride, which is only feasible following the reaction of the elemental mercury and the residual mercuric chloride present within the cells. Besides the sequestration and intracellular transformation, a significant fraction of the mercury (63%) was also volatilized. The 16S rRNA gene sequence of RS-5 revealed its phylogenetic relationship with the family Bacillaceae, and a 98% homology with Lysinibacillus fusiformis, a Gram-positive bacterium with swollen sporangia. This is the first observation of the sequestration and volatilization of mercuric ions by Lysinibacillus sp.

• Research in Plant Disease
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• v.19 no.4
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• pp.254-258
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• 2013

Fusaric acid (FA) is a mycotoxin produced by Fusarium species. Its toxicity is relatively low but often associated with other mycotoxins, thus enhancing total toxicity. To date, biosynthetic genes or enzymes for FA have not been identified in F. oxysporum. In order to explore the genetic element(s) for FA biosynthesis, restriction enzyme mediated integration (REMI) procedure as an insertional mutagenesis was employed using FA producing-F. oxysporum strains. Genetic transformation of two F. oxysporum strains by REMI yielded more than 7,100 transformants with efficiency of average 3.2 transformants/${\mu}g$ DNA. To develop a screening system using phytotoxicity of FA, eleven various grains and vegetable seeds were tested for germination in cultures containing FA: Kimchi cabbage seed was selected as the most sensitive host. Screening for FA non-producer of F. oxysporum was done by growing each fungal REMI transformant in Czapek-Dox broth for 3 weeks at $25^{\circ}C$ then observing if the Kimchi cabbage seeds germinated in the culture filtrate. Of more than 5,000 REMI transformants screened, fifty-three made the seeds germinated, indicating that they produced little or fewer FA. Among them, twenty-six were analyzed for FA production by HPLC and two turned out to produce less than 1% of FA produced by a wild type strain. Sequencing of genomic DNA regions (252 bp) flanking the vector insertion site revealed an uncharacterized genomic region homologous (93%) to the F. fujikuroi genome. Further study is necessary to determine if the vector insertion sites in FA-deficient mutants are associated with FA production.

• Biotechnology and Bioprocess Engineering:BBE
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• v.1 no.1
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• pp.36-40
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• 1996

For the production of cis, cis-muconic acid via biocatalytic conversion reactions from a toxic cosubstrate, benzoic acid, a fed-batch process using computer-controlled DO-stat feeding was developed. The mutant strain of Pseudomonas putida BM014 produced cis, cis-muconic acid from benzoic acid with high conversion yield. More than 32 g/L of cis, cis-muconic acid was accumulated in 42h and a productivity of 1.4g/(L.h)was achieved.

• 한국약용작물학회:학술대회논문집
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• 2008.11a
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• pp.123-124
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• 2008

• Journal of Microbiology and Biotechnology
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• v.19 no.10
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• pp.1150-1152
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• 2009

Geraniol (1) is the biogenetic precursor of a number of monoterpenes. We tested various marine-derived microorganisms to determine their ability to biotransform 1. Only Hypocrea sp. was capable of transforming 1 into its oxidized derivative, 1,7-dihydroxy-3,7-dimethyl-(E)-oct-2-ene (2). The structure of the metabolite obtained was assigned on the basis of detailed spectroscopic data analyses.

• Journal of Microbiology and Biotechnology
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• v.25 no.11
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• pp.1773-1781
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• 2015

Environmental security is one of the major concerns for the safety of living organisms from a number of harmful pollutants in the atmosphere. Different initiatives, legislative actions, as well as scientific and social concerns have been discussed and adopted to control and regulate the threats of environmental pollution, but it still remains a worldwide challenge. Therefore, there is a need for developing certain sensitive, rapid, and selective techniques that can detect and screen the pollutants for effective bioremediation processes. In this perspective, isolated enzymes or biological systems producing enzymes, as whole cells or in immobilized state, can be used as a source for detection, quantification, and degradation or transformation of pollutants to non-polluting compounds to restore the ecological balance. Biosensors are ideal for the detection and measurement of environmental pollution in a reliable, specific, and sensitive way. In this review, the current status of different types of microbial biosensors and mechanisms of detection of various environmental toxicants are discussed.

• Journal of Marine Bioscience and Biotechnology
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• v.2 no.1
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• pp.11-22
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• 2007

This aims to review natural products transformed by mimic intestinal metabolisms with microorganisms and hydrolytic enzymes, which exhibit enforced biological activity, higher extraction yield and identification of active components. In the process, transformation to the smaller active compounds with enzymes and microbes mimics the pharmacological action of natural products by intestinal bacteria. In order to establish conditions for the fermentation and enzyme reaction, it is required to choose several natural products for biotransformation and investigate the optimal conditions for the fermentation or the enzyme reaction such as composition, temperature, pH, inoculum, and cultivation time. It is expected an increase of the internal absorption of the active materials without regard to the intestinal microbes or its ability through biosynthesis of the active materials by the microbes and enzymes. And this techniques can be applied to biotransformation of natural products such as sesaminol, resveratrol, 1-deoxy nojirimycin, naringenin, quercetin, and baicalin and to the metabolism study using the animal model.