• The Korean Journal of Mycology
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• v.24 no.2 s.77
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• pp.104-110
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• 1996

The effect of nutritional and cultural conditions for the production of anti-complementary polysaccharide from Pleurotus sajor-caju was studied. Maximum anti-complementary activity from its culture broth and mycelium was obtained by using lactose and maltose as a carbon source, respectively. Ammonium phosphate (monobasic) and serine were chosen for the highest activity among the inorganic nitrogen compounds and amino acids tested. Optimum temperature for the production of the anti-complementary polysaccharide was $25^{\circ}C$.

• KSBB Journal
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• v.9 no.2
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• pp.224-229
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• 1994

Iturin, an antifungal lipopeptide, fermentation by Bacillus subtilis was investigated focusing on the effeats of nutrients aeration and specific cell growth rate on iturin production. Cell growth and product formation were not affected by different kinds of carbon sources such as sucrose, glucose and fructose. Soytone concentration above 20g/$\ell$ did not influence iturin production. Diauxic growth pattern appeared when only soytone was used as a sole nitrogen source probably due to the shortage of amino acids and/or peptides in soytone which could be favorably assimilated by the cells. The composition of three major components in iturin was not changed significantly by the variation of dissolved oxygen concentration of the culture broth but changed substantially by the change of specific growth rate of the cells.

• Mycobiology
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• v.36 no.2
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• pp.88-92
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• 2008

Vegetative growth of four different strains of Hericium erinaceus was observed. The temperature suitable for optimal mycelial growth was determined to be $25^{\circ}C$, with growth observed in the extend temperature range of $20{\sim}30^{\circ}C$. The different strains of this mushroom showed distinct pH requirements for their optimum vegetative growth, with the most favorable growth observed at pH 6. Considering vegetative mycelial growth, PDA, YM, Hennerberg, Hamada, and Glucose peptone were the most favorable media, and Czapek Dox, Hoppkins, Glucose tryptone, and Lilly were the most unfavorable media for these mushroom strains. With the exception of lactose, most of the carbon sources assayed demonstrated favorable vegetative growth of H. erinaceus. For mycelial growth, the most suitable nitrogen source was alanine and the most unsuitable was histidine. Oak sawdust medium supplemented with $10{\sim}20%$ rice bran was the best for mycelial growth of the mushroom.

• Journal of Microbiology
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• v.40 no.3
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• pp.193-198
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• 2002

Several 2,4,6-trinitrotoluene (TNT) degrading bacteria were isolated from an activated sludge by an enrichment culture technique, and their TNT removal activities were examined. Among the isolates, strain C1 showed the highest degrading capability, and completely removed 100 or 200 mg I$\^$-1/ of TNT within 6 hours of incubation. This bacterium was identified as Klebsiella sp. The effects of different carbon sources on the removal of the parent TNT by Klebsiella sp. C1 were negligible, but the transformation rates of TNT metabolites such as amino-dinitrotoluenes and diamino-nitrotoluenes were higher with fructose addition compared to glucose addition. When nitrate was used as the nitrogen source, the degradation rates of TNT and hydroxylamino-dinitrotoluenes were higher than those with the ammonium addition. Although the TNT removal rate of Klebsiella sp. C1 was slightly higher in anaerobic conditions, the further transformations of TNT metabolites were more favorable in aerobic conditions.

• Journal of Microbiology and Biotechnology
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• v.23 no.3
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• pp.351-356
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• 2013

A high ${\beta}$-glucosidase (BGL)-producing strain, Stereum hirsutum, was identified and isolated and showed a maximum BGL activity (10.4 U/ml) when cultured with Avicel and tryptone as the carbon and nitrogen sources, respectively. In comparison with other BGLs, BGL obtained from S. hirsutum showed a higher level of activity to cellobiose ($V_{max}$ = 172 U/mg, and $k_{cat}$ = 281/s). Under the optimum conditions (600 rpm, $30^{\circ}C$, and pH 6.0), the maximum BGL activity of 10.4 U/ml with the overall productivity of 74.5 U/l/h was observed. BGL production was scaled up from a laboratory scale (7-L fermenter) to a pilot scale (70-L fermenter). When S. hirsutum was cultured in fed-batch culture with rice straw as the carbon source in a 70-L fermenter, a comparable productivity of 78.6 U/l/h was obtained. Furthermore, S. hirsutum showed high levels of activity of other lignocellulases (cellobiohydrolase, endoglucanase, xylanase, and laccase) that are involved in the saccharification of biomasses. Application of S. hirsutum lignocellulases in the hydrolysis of Pinus densiflora and Catalpa ovata showed saccharification yields of 49.7% and 43.0%, respectively, which were higher than the yield obtained using commercial enzymes.

• Korean Journal of Materials Research
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• v.33 no.12
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• pp.530-536
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• 2023

The theoretical capacity of silicon-based anode materials is more than 10 times higher than the capacity of graphite, so silicon can be used as an alternative to graphite anode materials. However, silicon has a much higher contraction and expansion rate due to lithiation of the anode material during the charge and discharge processes, compared to graphite anode materials, resulting in the pulverization of silicon particles during repeated charge and discharge. To compensate for the above issues, there is a growing interest in SiO_x materials with a silica or carbon coating to minimize the expansion of the silicon. In this study, spherical silica (SiO₂) was synthesized using TEOS as a starting material for the fabrication of such SiO_x through heating in a reduction atmosphere. SiO_x powder was produced by adding PVA as a carbon source and inducing the reduction of silica by the carbothermal reduction method. The ratio of TEOS to distilled water, the stirring time, and the amount of PVA added were adjusted to induce size and morphology, resulting in uniform nanosized spherical silica particles. For the reduction of the spherical monodisperse silica particles, a nitrogen gas atmosphere mixed with 5 % hydrogen was applied, and oxygen atoms in the silica were selectively removed by the carbothermal reduction method. The produced SiO_x powder was characterized by FE-SEM to examine the morphology and size changes of the particles, and XPS and FT-IR were used to examine the x value (O/Si ratio) of the synthesized SiO_x.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.77-82
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• 2004

Quantifying rates of microbial processes under subsurface conditions is difficult, and is most commonly approximated by laboratory studies using aquifer materials. In this study a single-well, 'push-pull' test method is adapted for the in situ determination of denitrification rates in groundwater aquifers. The rates of stepwise reduction of nitrate to nitrite, nitrous oxide, and molecular nitrogen were determined by performing a series of push-pull tests at an experimental well field of Korea University. A single Transport Test, one Biostimulation Test, and four Activity Tests were conducted for this study. Transport tests are conducted to evaluate the mobility of solutes used in subsequent tests. These included bromide (a conservative tracer), fumarate (a carbon and/or source), and nitrate (an electron acceptor). At this site, extraction phase breakthrough curves for all solutes were similar, indicating apparent conservative transport of the solutes prior to biostimulation. Biostimulation tests were conducted to stimulate the activity of indigenous heterotrophic denitrifyinc microorganisms. Biostimulation was detected by the simultaneous production of carbon dioxide and nitrite after each injection. Activity tests were conducted to quantify rates of nitrate, nitrite, and nitrous oxide reduction. Estimated zero-order degradation rates decreased in the order nitrate '||'&'||'gt; nitrite '||'&'||'gt; nitrous oxide. The series of push-pull tests developed and field tested in this study should prove useful for conducting rapid, low-cost feasibi1ity assessments for in situ denitrification in nitrate-contaminated aquifers.

• Journal of Microbiology and Biotechnology
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• v.21 no.7
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• pp.739-745
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• 2011

During the production of grape wine, the formation of thick leathery pellicle/bacterial cellulose (BC) at the airliquid interface was due to the bacterium, which was isolated and identified as Gluconacetobacter hansenii UAC09. Cultural conditions for bacterial cellulose production from G. hansenii UAC09 were optimized by central composite rotatable experimental design. To economize the BC production, coffee cherry husk (CCH) extract and corn steep liquor (CSL) were used as less expensive sources of carbon and nitrogen, respectively. CCH and CSL are byproducts from the coffee processing and starch processing industry, respectively. The interactions between pH (4.5-8.5), CSL (2-10%), alcohol (0.5-2%), acetic acid (0.5-2%), and water dilution rate to CCH ratio (1:1 to 1:5) were studied using response surface methodology. The optimum conditions for maximum BC production were pH (6.64), CSL (10%), alcohol (0.5%), acetic acid (1.13%), and water to CCH ratio (1:1). After 2 weeks of fermentation, the amount of BC produced was 6.24 g/l. This yield was comparable to the predicted value of 6.09 g/l. This is the first report on the optimization of the fermentation medium by RSM using CCH extract as the carbon source for BC production by G. hansenii UAC09.

• Microbiology and Biotechnology Letters
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• v.1 no.1
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• pp.13-18
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• 1973

For the production of Nucleic acid derivatives by microorganisms, adenineless mutants were induced from Bacillus subtilis with the mutagens, ultraviolet rays and diethylsulfate. And total strains of 62 adenineless mutants were isolated. These mutants were found to have an ability of accumulating u. v. absorbing substances in the culture broth. They were analyzed to be hypoxanthine, uracil, and other unknown compound by means of two dimensional thin layer chromatography, u. v. absorption spectra, and I. R. absorption spectrum. Mutant BS-137 was screened out to accumulate hypoxanthine, which was isolated from the culture broth through activated carbon column and recrystallize from cold water. The effect of the medium compositions on hypoxanthine accumulation were examined for the mutant BS-137. Glucose appeared to be the best carbon source, but molasses could be substitute for it, NaNO$_3$ and yeast extract were especially good sources of nitrogen.

• Korean Chemical Engineering Research
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• v.44 no.1
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• pp.52-57
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• 2006

Bacterial cellulose (BC) was produced by Gluconacetobacter hansenii PJK (KCTC 10505 BP) strains using the waste of beer fermentation broth. It contained more C and N than a basal medium with a small amount of S and more than 4％ ethanol. The amount of BC produced in a shaking culture using the waste of beer fermentation broth was nearly the same as that of a basal medium. The production of BC decreased in a shear stress field in a jar fermenter although the conversion of cellulose producing ($Cel^+$) cells to non-cellulose producing ($Cel^-$) mutants was not severe. This study showed that the waste of beer fermentation broth is an inexpensive carbon, nitrogen source with ethanol and thus a worthy substitute for the conventional medium for BC production.