• Journal of Microbiology and Biotechnology
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• v.5 no.1
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• pp.36-40
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• 1995

Valistatin, a new inhibitor of aminopeptidase M(AP-M) was discovered in the culture broth of Streptomyces sp. SL20209 isolated from a soil sample. The inhibitor was purified by extraction with n-butanol and the various column chromatographies, and then isolated as whitish powder. The $^1 H-and ^1 H, ^1 H-COSY$ NMR studies, amino acid analysis, and fragmentation patterns by FAB-MS suggested the presence of one 3-amino-2-hydroxy-4-phenylbutanoic acid and two valine residues in the inhibitor. Thus, the structure of valistatin was determined as 3-amino-2-hydroxy-4-phenylbutanoyl-valyl-valine. Valistatin has the molecular formular $C_20H_31N_3 O_5$ (MW 394), and its $IC_50$ value against hog kidney AP-M was determined to be 3.12 $mu g/ml$.

• Journal of Microbiology and Biotechnology
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• v.25 no.7
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• pp.1101-1107
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• 2015

The role of CRE1 in a thermophilic fungus, Myceliophthora thermophila ATCC42464, was studied using RNA interference. In the cre1-silenced strain C88, the filter paper hydrolyzing activity and β-1,4-endoglucanase activity were 3.76-, and 1.31-fold higher, respectively, than those in the parental strain when the strains were cultured in inducing medium for 6 days. The activities of β-1,4-exoglucanase and cellobiase were 2.64-, and 5.59-fold higher, respectively, than those in the parental strain when the strains were cultured for 5 days. Quantitative reverse-transcription polymerase chain reaction showed that the gene expression of egl3, cbh1, and cbh2 was significantly increased in transformant C88 compared with the wild-type strain. Therefore, our findings suggest the feasibility of improving cellulase production by modifying the regulator expression, and an attractive approach to increasing the total cellulase productivity in thermophilic fungi.

• Journal of Microbiology and Biotechnology
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• v.19 no.9
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• pp.858-868
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• 2009

The abundance, biomass, size distribution, and taxonomic composition of bacterial and protistan (heterotrophic and autotrophic nanoflagellates and ciliates) communities were investigated in six lakes of Masurian Lake District (north-eastern Poland) differing in trophic state. Samples were taken from the trophogenic water layer during summer stratification periods. Image analysis techniques with fluorescent in situ hybridization (FISH) as well as [$^3H$]-methyl-thymidine incorporation methods were applied to analyze differences in the composition and activity of bacterial communities. The greatest differences in trophic parameters were found between the humic lake and remaining non-humic ones. The same bacterial and heterotrophic nanoflagellate (HNF) cell size classes dominated in all the studied lakes. However, distinct increases in the contributions of large bacterial (>$1.0{\mu}m$) and HNF (>$10{\mu}m$) cells were observed in eutrophic lakes. The bacterial community was dominated by the ${\beta}$-Proteohacteria group, which accounted for 27% of total DAPI counts. Ciliate communities were largely composed of Oligotrichida. Positive correlations between bacteria and protists, as well as between nanoflagellates (both heterotrophic and autotrophic) and ciliates, suggest that concentrations of food sources may be important in determining the abundance of protists in the studied lakes.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.6
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• pp.670-674
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• 2005

The respiratory quinone profile was used as a tool for the study on microbial community structure in the mine tailings of abandoned mines over the depth. For the study, the area of Jingok mine located in Bongwha, Korea has been selected. The distributions of Cd, Cu, Pb, Al, Fe and Mn showed the following common patterns; the highest values in the upper part of mine failings (0-20 cm), rapid decrease with increasing depth. The dominant quinone species of the mine tailings were UQ-9 followed by UQ-10, suggesting that microbes had contributed to heavy metal degradation. The quinone contents in mine tailings ranged from 5.0 to 24.9 nmol/kg. The microbial diversity in the upper part of mine tailings (0-40 cm) was higher than that of lower part of mine tailings (100-120 cm).

• Archives of Pharmacal Research
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• v.21 no.3
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• pp.278-285
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• 1998

The microdilution assay recommended by NCCLS (National Committee for Clinical Laboratory Standards) is one of the standardized methods of antibiotic susceptibility test. This method has been widely used clinically to obtain MIC values of antibiotics on pathogenic microorganisms. It is more convenient, rapid and simple to test many samples than other test methods such as agar diffusion assay and broth macrodilution assay. The screening of antimicrobial agents from microbial extracts is too laborious in its process. Therefore, a number of screening methods having more simple procedure have been developed. In our laboratory, we applied microdilution assay for screening the antimicrobial agents. This assay showed dose-response results and was more sensitive than disc diffusion assay in our system. We tested 200 samples of microbial extracts originated from 100 microbial strains and selected several samples as potential candidates. In this report, we show that the microdilution assay is more convenient method in screeing of antibiotic susceptibility than those previously reported.

• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.3
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• pp.207-210
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• 2000

When endothelial cells isolated isolated from human umbilical venis were cultred for 6dary using 96-well microplates, the final cell density in each was fiund not to be the same although the medium composition of each well was exactly the same. Cell growth in the wells located at the periphery of a microplate was low, while that in the central area of the plate was high. A possible cause for different rate of growth was proposed as the uneven concentration of oxygen in the culture medium of each well.

• Food Science of Animal Resources
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• v.30 no.6
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• pp.886-895
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• 2010

The level of fat and salt can affect the product quality and storage stability of processed meats. Additionally, consumers' demands require dietary guidelines for developing low-fat/salt functional foods. Microbial transglutaminase (MTGase), which enhances textural properties by catalyzing protein-protein cross-linkages, was introduced to develop healthier lowfat/salt meat products. The potential possibilities of low-fat/salt processed meats were reviewed under optimal conditions for functional ingredients from several previous studies. The addition of non-meat protein (e.g. sodium caseinate and soy protein isolates), hydrocolloids (e. g. konjac flour, carrageenan, and alginates), and MTGase alone or in combination with other functional ingredients improved textural and sensory properties similar to those of regularly processed meats. When MTGase was combined with hydrocolloids (konjac flour or sodium alginate) or other functional ingredients, gelling properties of meat protein were improved even at a low salt level. Based on these reviews, functional ingredients combined with new processing technologies could be incorporated into processed meats to improve the functionality of various low-fat/salt meat products.

• Journal of Microbiology and Biotechnology
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• v.22 no.2
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• pp.270-273
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• 2012

These studies were conducted to determine the effects of various concentrations of ammonium and nitrate on current generation using dual-cathode microbial fuel cells (MFCs). Current generation was not affected by ammonium up to $51.8{\pm}0.0$ mg/l, whereas $103.5{\pm}0.0$ mg/l ammonium chloride reduced the current slightly. On the other hand, when $60.0{\pm}0.0$ and $123.3{\pm}0.1$ mg/l nitrate were supplied, the current was decreased from $10.23{\pm}0.07$ mA to $3.20{\pm}0.24$ and $0.20{\pm}0.01$ mA, respectively. Nitrate did not seem to serve as a fuel for current generation in these studies. At this time, COD and nitrate removal were increased except at $123{\pm}0.1$ mg ${NO_3}^-/l$. These results show that proper management of ammonium and nitrate is very important for increasing the current in a microbial fuel cell.

• Journal of Microbiology and Biotechnology
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• v.29 no.10
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• pp.1624-1628
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• 2019

Banana planting altered microbial communities and induced the enrichment of Fusarium oxysporum in rhizosphere compared with that of forest soil. Diseased plant rhizosphere soil (WR) harbored increased pathogen abundance and showed distinct microbial structures from healthy plant rhizosphere soil (HR). The enriched taxon of Bordetella and key taxon of Chaetomium together with some other taxa showed negative associations with pathogen in HR, indicating their importance in pathogen inhibition. Furthermore, a more stable microbiota was observed in HR than in WR. Taken together, the lower pathogen abundance, specific beneficial microbial taxa and stable microbiota contributed to disease suppression.

• Journal of Microbiology and Biotechnology
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• v.31 no.6
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• pp.765-774
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• 2021

Although research on the osteal signaling pathway has progressed, understanding of gut microbial-dependent signaling pathways for metabolic and immune bone homeostasis remains elusive. In recent years, the study of gut microbiota has shed light on our understanding of bone homeostasis. Here, we review microbiota-mediated gut-bone crosstalk via bone morphogenetic protein/SMADs, Wnt and OPG/receptor activator of nuclear factor-kappa B ligand signaling pathways in direct (translocation) and indirect (metabolite) manners. The mechanisms underlying gut microbiota involvement in these signaling pathways are relevant in immune responses, secretion of hormones, fate of osteoblasts and osteoclasts and absorption of calcium. Collectively, we propose a signaling network for maintaining a dynamic homeostasis between the skeletal system and the gut ecosystem. Additionally, the role of gut microbial improvement by dietary intervention in osteal signaling pathways has also been elucidated. This review provides unique resources from the gut microbial perspective for the discovery of new strategies for further improving treatment of bone diseases by increasing the abundance of targeted gut microbiota.