• The Korean Journal of Mycology
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• v.48 no.3
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• pp.273-284
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• 2020

Calocybe indica is an edible mushroom commercially cultivated in India and other tropical countries. In this study, the culture characteristics and optimal conditions of milky mushroom strains were determined. The growth temperature and pH range of milky mushrooms was extensively investigated between 15-35 ℃ and pH 3-11. For efficient cultivation, 20 types of nutrient sources were selected that consisted of one of 21 types of carbon sources, 6 organic nitrogen sources, 6 inorganic nitrogen sources, 13 amino acids, 6 organic acids and 12 inorganic salts. The impact of each of the selected nutrition sources and their concentration on growth was investigated. The optimum pH and temperature were determined to be pH 6.0 and 15 ℃, respectively. The optimum concentration of medium elements for the mycelial growth of C. indica was determined to be as follows: carbon source, 2% maltose; organic nitrogen source, 1% yeast extract; inorganic nitrogen source, 0.1% NaNO₃; amino acid, 0.7% asparagine; organic acid, 0.07% acetic acid; inorganic salt, 0.07 mM MnSO₄.

• Plant Resources
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• v.8 no.1
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• pp.60-66
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• 2005

Lysine is the first essential amino acid for optimal nutrient quality in rice grain. For the narrow genetic diversities of lysine contents in rice, somaclonal variation was the source of mutation in our breeding program. Biochemical selection was conducted using 1 mM S-(2-aminoethyl) cysteine followed by two passages of 5 mM lysine plus threonine in the callus subculture medium. The lysine contents in endosperm of all progenies recovered from the biochemical selection were higher than those of their donor cultivar 'Hwayeongbyeo'. These elevated lysine levels of mutants were successfully transmitted to $M_4$ generation. The lysine contents in endosperm varied 3.85 to $4.80\%$ compare to their donor cultivar 'Hwayeongbyeo' was $3.85\%$. Three of high-lysine germplasms, Lys-l, Lys-2 and Lys-7 were selected by biochemical selection and rapid screening methods. DNA analysis showed that a new insertion of Tos 17 which mapped to rice chromosome 11 on the high-lysine mutant, Lys-2.

• Journal of Environmental Science International
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• v.1 no.1
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• pp.77-88
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• 1992

Distribution patterns of the chemical species, contained or dissolved in the sediments and porewater, were studied from the submarine environments around Deok-Jeok Island, Yellow Sea. The sediments in the study area are predominantly composed of medium to coarse sands, and consequently of very low organic carbon (0.003%) -0.26%o dry weight sediments). As opposed to the strong enrichment of porewater with nutrients and heavy metals in the ordinarily muddy, organic-rich sediillents, the porewater enrichment is not intense in this sandy, organic-poor sediments: porewater phosphate is enriched to the maximum of only seven (average two) times over that in the bottom water. Concentrations of the heavy metals dissolved in porewater show a bit greater enrichment than the nutrient: Zn shows the lowest enrichment (7 times that of the bottom water) and Mn the highest (450 times that of the bottom water). However, these enrichments of the chemical species in porewater are the natural consequences of decomposition of the organic matter in sediments, and still fall short in the magnitude of those in the muddy, organic-rich sediments. Mining of the sands in the study area may pose a threat to the seawater quality as it causes a large scale porewater discharge to the bottom water. The additional supply of the nutrients by this discharge may develop an eutrophic state and, in consequence, an excessive nitrification of the water column. Since the residence times of the nutrients are much longer than those of the heavy metals, a long-term monitoring of the concentration changes in the porewater nutrients is very important to assess the potential deterioration of the seawater associated with the sand mining in the study area.

• Microbiology and Biotechnology Letters
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• v.32 no.2
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• pp.123-127
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• 2004

Pseudomonas sp. MBEL21 was newly isolated from soil samples and found to accumulate medium-chain-length Polyhydroxyalkanoates(MCL-PHAs) using oleic acid as a sole carbon source. Among the various nutrient limiting conditions examined, including nitrogen, sulfur and phosphorus, only phosphorus limitation supported the accumulation of MCL-PHAs up to 15 wt％ of dry cell weight in flask cultures. MCL-PHAs produced by Pseudomonas sp. MBEL21 was mainly composed of 3-hydroxy-5-cis-tetradecenoate. Fed-batch culture of Pseudomonas sp. MBEL21 by novel feeding strategies based on cell growth charcteristics was carried out under phosphorus limitation using oleic acid as a sole carbon source. The final cell concentration and PHA content of 82 g/L and 28 wt％, respectively, were obtained. Furthermore, PHA consisted of MCL-hydroxyalkanoates and 3-hydroxybutyrate could be produced using olive oil as a sole carbon source.

• Journal of Microbiology and Biotechnology
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• v.22 no.12
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• pp.1621-1628
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• 2012

The agar-degrading bacterium GNUM-1 was isolated from the brown algal species Sargassum serratifolium, which was obtained from the West Sea of Korea, by using the selective artificial seawater agar plate. The cells were Gram-negative, $0.5-0.6{\mu}m$ wide and $2.0-2.5{\mu}m$ long curved rods with a single polar flagellum, forming nonpigmented, circular, smooth colonies. Cells grew at $20^{\circ}C-37^{\circ}C$, between pH 5.0 and 9.0, and at 1-10% (w/v) NaCl. The DNA G+C content of the GNUM-1 strain was 45.5 mol%. The 16S rRNA sequence of the GNUM-1 was very similar to those of Alteromonas stellipolaris LMG 21861 (99.86% sequence homology) and Alteromonas addita $R10SW13^T$(99.64% sequence homology), which led us to assign it to the genus Alteromonas. It showed positive activities for agarase, amylase, gelatinase, alkaline phosphatase, esterase (C8), lipase (C14), leucine arylamidase, valine arylamidase, ${\alpha}$-chymotrypsin, acid phosphatase, naphthol-AS-BI-phosphohydrolase, ${\alpha}$-galactosidase, ${\beta}$-galactosidase, ${\beta}$-glucosidase, catalase, and urease. It can utilize citrate, malic acid, and trisodium citrate. The major fatty acids were summed feature 3 (21.5%, comprising $C_{16:1}{\omega}7c/iso-C_{15:0}$ 2-OH) and C16:0 (15.04%). On the basis of the variations in many biochemical characteristics, GNUM-1 was considered as unique and thus was named Alteromonas sp. GNUM-1. It produced the highest agarase activity in modified ASW medium containing 0.4% sucrose, but lower activity in rich media despite superior growth, implying that agarase production is tightly regulated and repressed in a rich nutrient condition. The 30 kDa protein with agarase activity was identified by zymography, and this report serves as the very first account of such a protein in the genus Alteromonas.

• Microbiology and Biotechnology Letters
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• v.16 no.6
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• pp.450-456
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• 1988

For optimal production of L-tryptophan using a regulatory mutant of Escherichia coli the relationship between product formation and acid production was investigated. Experimental results showed that the production level of L-tryptophan was lowered as the specific acid production rate increased. In order to reduce the amount of acid produced during the fermentation, a controlled fed-batch fermentation was employed. In this fed-batch process, the feed rate of the nutrient feed medium was controlled in relation to the oxygen level in the culture and thus the growth of the cells was regulated in such n way that the oxygen demand of the culture could not exceed the oxygen sup-ply. When E. coli cells were cultivated in a controlled fed-batch mode of tormentor operation, the specific acid production rate was significantly reduced and L-tryptophan production was increased as much as five times that obtained in a conventional fed-batch fermentation.

• Journal of Microbiology
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• v.37 no.4
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• pp.248-255
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• 1999

We have analyzed the MRE3/REC114 gene of Saccharomyces cerevisiae, previously detected in isolation of mutants defective in meiotic recombination. We cloned the MRE3/REC114 gene by complementation of the meiotic recombination defect and it has been mapped to chormosome XIII. The DNA sequence analysis revealed that the MRE3 gene is identical to the REC114 gene. The upstream region of the MRE3/REC114 gene contains a T_4C site, a URS (upstream repression sequence) and a TR (T-rich) box-like sequence, which reside upstream of many meiotic genes. Coincidentally, northern blot analysis indicated that the three sizes of MRE3/REC114 transcripts, 3.4, 1.4 and 1.2 kb, are induced in meiosis. A less abundant transcript of 1.4 kb is detected in both mitotic and meiotic cells, suggesting that it is needed in mitosis as well as meiosis. To examine the role of the MRE3/REC114 gene, we constructed mre3 disruption mutants. Strains carrying an insertion or null deletion of the MRE3/REC114 gene showed slow growth in nutrient medium and the doubling time of these cells increased approximately by 2-fond compared to the wild-type strain. Moreover, the deletion mutant (${\delta}$mre3) displayed no meiotically induced recombination and no viable spores. The mre3/rec114 spore lethality can be suppressed by spo13, a mutation that causes cells to bypass reductional division. The double-stranded breaks (DSBs) which are involved in initiation of meiotic recombination were not detected in the analysis of meiotic chromosomal DNA from the mre3/rec114 disruptant. From these results we suggest that the MRE3/REC114 gene product is essential in normal growth and in early meiotic stages involved in meiotic recombination.

• Journal of Nutrition and Health
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• v.41 no.4
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• pp.353-364
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• 2008

In this study elementary school children's food purchasing and consumer competency for a healthier diet were compared by their attitude toward the meal management. The subjects were 779 sixth grade elementary school children (417 boys and 362 girls) in Busan. They were classified into three groups: 'High' was composed of 226 subjects who had more than the mean +1/2 SD of attitude toward the meal management; 'Medium' was composed of 343 subjects who had the mean ${\pm}1/2$SD; and 'Low' was composed of 210 subjects who had the less than the mean -1/2 SD. The results were as follows. The high group had less pocket money than the low group, and thought that their allowances were adequate to their needs. They also had a habit of entering amounts into an account book. The children in the low group purchased mostly snacks without making or practicing a budget. The high group purchased yogurt, fruit, or bread as snacks more frequently than the low group. More children checked the nutrient facts on the package in high group than in the low group. There were no significant differences in the consumer's knowledge of a healthy diet among the groups; but there were significant differences in the consumer's skill, and the consumer's attitude toward a healthy diet among the groups. The high group had higher skills and more positive attitudes than the low group. This research suggests that education can elevate interest and can help develop more positive attitudes toward healthy diets among children. The education can help them to develop planned food purchasing habits, and improve their consumer competency for a healthy diet.

• Animal cells and systems
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• v.15 no.2
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• pp.147-154
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• 2011

Animal cell cultures generally require a nutrient-rich medium supplemented with animal serum. Adult bovine serum contains a variety of nutrients including inorganic minerals, vitamins, salts, proteins and lipids as well as growth factors that promote animal cell growth. To evaluate the potential use of gender-specific bovine serum (GSBS) for cell culture, the biochemical properties of male serum (MS), female serum (FS) and castrated-male serum (CMS) were investigated. Overall, the chemical profile of GSBS was similar to that of bovine references except for glucose, creatine kinase, lactate dehydrogenase and potassium. FS showed elevated total protein and sodium concentrations compared to MS and CMS. Proteins present in MS, FS and CMS but absent in fetal bovine serum (FBS) were selected by two-dimensional gel electrophoresis and identified by peptide mass fingerprinting. Some of the identified proteins are known to be involved in immune responses and the others have unknown physiological roles. Moreover, it was found that some proteins such as alpha-2-macroglobulin appeared to be gender-specific with higher contents in FS. Insulin and testosterone was significantly higher in MS, and $17{\beta}$-estradiol and estrone were higher in FS, as compared to the other sera. Taken together, the results indicate that each GSBS has a different ratio of components. Differences in serum constituents may affect cell cultures in a different manner and could be beneficial, depending on the specific aim of cell cultures.

• Journal of Microbiology and Biotechnology
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• v.33 no.10
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• pp.1337-1350
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• 2023

Caproic acid is a precursor substance for the synthesis of ethyl caproate, the main flavor substance of nongxiangxing baijiu liquor. In this study, Clostridium butyricum GD1-1, a strain with high caproic acid concentration (3.86 g/l), was isolated from the storage pit mud of nongxiangxing baijiu for sequencing and analysis. The strain's genome was 3,840,048 bp in length with 4,050 open reading frames. In addition, virulence factor annotation analysis showed C. butyricum GD1-1 to be safe at the genetic level. However, the annotation results using the Kyoto Encyclopedia of Genes and Genomes Automatic Annotation Server predicted a deficiency in the strain's synthesis of alanine, methionine, and biotin. These results were confirmed by essential nutrient factor validation experiments. Furthermore, the optimized medium conditions for caproic acid concentration by strain GD1-1 were (g/l): glucose 30, NaCl 5, yeast extract 10, peptone 10, beef paste 10, sodium acetate 11, L-cysteine 0.6, biotin 0.004, starch 2, and 2.0% ethanol. The optimized fermentation conditions for caproic acid production by C. butyricum GD1-1 on a single-factor basis were: 5% inoculum volume, 35℃, pH 7, and 90% loading volume. Under optimal conditions, the caproic acid concentration of strain GD1-1 reached 5.42 g/l, which was 1.40 times higher than the initial concentration. C. butyricum GD1-1 could be further used in caproic acid production, NXXB pit mud strengthening and maintenance, and artificial pit mud preparation.