• Microbiology and Biotechnology Letters
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• v.20 no.5
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• pp.527-533
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• 1992

The optimal conditions for cellulase and xylanase production by Trichoderma reesei 28217 were studied for enzymatic deinking of old newspaper. The amounts of cellulase and xylanase from the strain was varied by initial medium pH, Tween 80, inoculum size of spore suspension, and carbon and nitrogen sources. The optimal conditions for cellulase production were pH 5.0-6.5, 0.02% of Tween 80, 0.5-1.0% of inoculum size of spore suspension ($1{\times}10^{7}$/ml). cottonseed meal as nitrogen source, and corn flour as carbon source. On the other hand, the optimal conditions for xylanase production were pH 6.5, 0.01% of Tween 80, corn steep liquor as nitrogen source, and disintegrated old newspaper as carbon source. The inoculum size for xylanase production was the same as for cellulase production. The concomitant production of cellulase and xylanase in shake flask culture was efficiently induced in the medium containing 0.5% cottonseed meal as nitrogen source and 1.0% old newspaper and 2.0% corn flour as carbon sources. In this case the activities of cellulase and xylanase produced were 6.11-7.22 IU/mJ and 97.7 IU/ml. respectively. However, the cellulase production in $5{\ell}$ fermentor scale was slightly decreased compared with that in flask scale. Moreover, xylanase production was severely reduced in a fermentor scale. The study for the reason of decreased enzyme production in fermentor is further needed.

• Korean Journal of Food Science and Technology
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• v.20 no.4
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• pp.518-525
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• 1988

Lactobacillus casei IFO 3012 and Kluyveromyces fragilis(KFCC 35458) were cultured together in Soymilk to investigate the growth characteristics and the conditions suitable for acid Production. L. casei produced more amount of acid rapidly when cultured with K. fragilis in soymilk than when cultured singly. The optimum conditions for acid production by the mixed cultures of L. casei and K. fragilis were achieved with a temperature of $35-37^{\circ}C$, a 1:5-1:9(O.D 660) ratio of L. casei to K. fragilis at inoculum, a 1.0 level of sucrose fortification or a 2.0% level of skim milk powder fortification and a culture time of 24hr. Under these conditions the amounts of acid produced by the single culture of L. casei and the mixed cultures with K. fragilis were 0.31% and 0.44% in soymilk, 0.43% and 0.97%, respectively, in soymilk fortified with 1.0% level of sucrose. These indicate that the amount of acid produced by mixed cultures is about 1.42 fold greater in soymilk and about 2.26 fold greater in soymilk fortified with 1.0% level of sucrose than that produced by the single culture of L. casei. The amount of acid produced in soymilk fortified with 2.0% level of skim milk powder was 1.0 level for both of the single culture of L. casei and the mixed cultures of L. casei and K. fragilis after 24hr incubation. In soymilk fortified with skim milk power less than 1.5 the mixed culture with K. fragilis showed higher content of acid than the single culture of L. casei only.

• Journal of Aquaculture
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• v.12 no.1
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• pp.31-38
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• 1999

The dietary value and fatty acids composition for the hatched neonates from the resting eggs of marine roofers, Brachionus plicatilis and B. rotundiformis were compared with that for mass-cultured rotifers (control) by feeding them to larvae of flounder (Paralichthy olivaceus) and parrot fish (Oplegnathus fasciatus). Resting eggs were mass-produced in $1~4m^3$tanks by feeding Chlorella sp. and baker's yeast. The B. plicatilis and B. rotundiformis eggs were preserved at $5^{\circ}C$ in darkness for 3 and 5 months, respectively, and hatched at $28^{\circ}C$ under continuous light. The hatched neonates from the resting eggs and mass-cultured rotifer, which was used as a rontrol were fed to fish larvaes. The growth and survival rates of parrot fish larvae fed on the neonates from the resting eggs of B. rotundiformis were similar to those of fish larvae fed on the control rotifer. And the growth and survival rates of the flounder larvae with neonates from the resting eggs of B. plicatilis were similar or higher than those fed the control rotifer. Also the fatty acids composition of the neonates from the resting eggs of B. plicatilis and B. rotundiformis were similar to those from the control rotifers. This results showed that the hatched neonates from resting eggs of rotifer could be used as an effective diet for flounder and parrot fish larvae.

• Journal of Life Science
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• v.27 no.12
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• pp.1403-1409
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• 2017

In this study, the xylitol dehydrogenase (XYL2) gene was expressed in Saccharomyces cerevisiae as a host cell for ease of use in the degradation of lignocellulosic biomass (xylose). To select suitable expression systems for the S.XYL2 gene from S. cerevisiae and the P.XYL2 gene from Pichia stipitis, $pGMF{\alpha}-S.XYL2$, $pGMF{\alpha}-P.XYL2$, $pAMF{\alpha}-S.XYL2$ and $pAMF{\alpha}-P.XYL2$ plasmids with the GAL10 promoter and ADH1 promoter, respectively, were constructed. The mating factor ${\alpha}$ ($MF{\alpha}$) signal sequence was also connected to each promoter to allow secretion. Each plasmid was transformed into S. cerevisiae $SEY2102{\Delta}trp1$ strain and the xylitol dehydrogenase activity was investigated. The GAL10 promoter proved more suitable than the ADH1 promoter for expression of the XYL2 gene, and the xylitol dehydrogenase activity from P. stipitis was twice that from S. cerevisiae. The xylitol dehydrogenase showed $NAD^+$-dependent activity and about 77% of the recombinant xylitol dehydrogenase was secreted into the periplasmic space of the $SEY2102{\Delta}trp1/pGMF{\alpha}-P.XYL2$ strain. The xylitol dehydrogenase activity was increased by up to 41% when a glucose/xylose mixture was supplied as a carbon source, rather than glucose alone. The expression system and culture conditions optimized in this study resulted in large amounts of xylitol dehydrogenase using S. cerevisiae as the host strain, indicating the potential of this expression system for use in bioethanol production and industrial applications.

• Journal of Soil and Groundwater Environment
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• v.9 no.3
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• pp.49-55
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• 2004

A soil enrichment LYF-1 culture from a contaminated site, which could reductively dechlorinate 900 $\mu$M (ca. 150 mg/L) of tetrachloroethylene (PCE) stoichimetrically into cis-1,2-dichloroethylene (cis-DCE), was established and characterized. The enrichment culture can use yeast extract, peptone, formate, acetate, lactate, pyruvate, citrate, succinate, glucose, sucrose, and ethanol as electron donors for dechlorination of PCE. Addition of NO$_2$$^{[-10]}$ and NO$_3$$^{[-10]}$ as alternative electron acceptors showed complete inhibition of PCE dechlorination, but S$_2$O$_3$$^{-2}$ , SO$_3$$^{-2}$ and SO$_4$$^{-2}$ had no significant effect on PCE dechlorination. The enrichment culture was attached to ceramic media in an anaerobic fixed-bed reactor. The fixed-bed reactor showed more than 99％ of PCE degradation in the range of PCE loading rate of 0.13-0.78 $\mu$moles/L/hr. The major end product of PCE dechlorination was cis-DCE.

• Journal of Life Science
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• v.29 no.3
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• pp.376-381
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• 2019

To construct useful yeast strain for bioethanol production, we improved yeast harboring various phenotypes by using yeast protoplast fusion method. In this study, S. cerevisiae BYK-F11 strain which have ethanol tolerance, thermotolerance and ${\beta}-glucanase$ activity and P. $stipitis{\Delta}ura$ strain which has xylose metabolism pathway were fused by genome shuffling. P. $stipitis{\Delta}ura$ strain was constructed for protoplast fusion by URA3 gene disruption, resulting in uracil auxotroph. By protoplast fusion, several fused cells were selected and BYKPS-F8 strain (fused cell) showing both karyotypes from two parent strains (S. cerevisiae BYK-F11 and P. $stipitis{\Delta}ura$ strain) among 22 fused cells was finally selected. Sequentially, various phenotypes such as ${\beta}-glucanase$ activity, xylose utility, ethanol tolerance, thermotolerance and ethanol productivity were analyzed. The BYKPS-F8 strain obtained ${\beta}-glucanase$ activity from BYK-F11 strain and 1.2 fold increased xylose utility from P. $stipitis{\Delta}ura$ strain. Also, the BYKPS-F8 strain showed thermotolerance at $40^{\circ}C$ and increased ethanol tolerance in medium containing 8% ethanol. In this fused cell, 7.5 g/l ethanol from 20 g/l xylose was produced and the multiple phenotypes were stably remained during long term cultivation (260 hr). It was proved that novel biological system (yeast strains) is easily and efficiently bred by protoplast fusion among yeasts having different genus.

• Korean Chemical Engineering Research
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• v.59 no.4
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• pp.542-547
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• 2021

Glass lined impellers are corrosion resistant to most chemicals, including strong acids, and also have a smooth, non-stick surface, easy to clean and free from impurities in the process. Glass lined home base impeller is a multi-purpose impeller designed to stir a wide viscosity range of liquids from low viscosity fluids to high viscosity fluids, among others, cell culture, yeast culture, and beer fermentation pots, especially used for air-water system breathable stirring. The glass lining for HB impellers, which are simple in structure and competitive in performance, is essential to have upper and lower division in order to make the joint area between the impeller and shaft as small as possible. The upper and lower division of the impeller hardly affects the mixing performance, but the aeration performance. In this study, in order to optimize the shape of the Glass Lining HB impeller, a study was conducted on the effect of the angle between the upper and lower impellers, the clearance between the impellers, and the number of baffles on the aeration power. The optimal shape and baffle plate conditions for the Glass lined HB impeller were derived through the study results that the angle and the clearance between the upper and lower impellers decreased the ration of the power consumption with aeration P_g and that without aeration P₀, P_g/P₀.

• Journal of Life Science
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• v.28 no.11
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• pp.1354-1360
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• 2018

The aim of this study was to develop a simple, environmentally friendly synthesis of silver nanoparticles (SNPs) without the use of chemical reducing agents by exploiting the extracellular synthesis of SNPs in a culture supernatant of Bacillus thuringiensis CH3. Addition of 5 mM $AgNO_3$ to the culture supernatant at a ratio of 1:1 caused a change in the maximum absorbance at 418 nm corresponding to the surface plasmon resonance of the SNPs. Synthesis of SNPs occurred within 8 hr and reached a maximum at 40-48 hr. The structural characteristics of the synthesized SNPs were investigated by various instrumental analysis. FESEM observations showed the formation of well-dispersed spherical SNPs, and the presence of silver was confirmed by EDS analysis. The X-ray diffraction spectrum indicated that the SNPs had a face-centered cubic crystal lattice. The average SNP size, calculated using DLS, was about 51.3 nm and ranged from 19 to 110 nm. The synthesized SNPs exhibited a broad spectrum of antimicrobial activity against a variety of pathogenic Gram-positive and Gram-negative bacteria and yeasts. The highest antimicrobial activity was observed against C. albicans, a human pathogenic yeast. The FESEM observations determined that the antimicrobial activity of the SNPs was due to destruction of the cell surface, cytoplasmic leakage, and finally cell lysis. This study suggests that B. thuringiensis CH3 is a potential candidate for efficient synthesis of SNPs, and that these SNPs have potential uses in a variety of pharmaceutical applications.

• Korean Journal of Poultry Science
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• v.30 no.3
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• pp.197-202
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• 2003

Feeding probiotics in broiler chicks still critical in several aspects. Thus, this study was conducted to investigate the impact of feeding multiple probiotics on performance, intestinal microflora, blood cholesterol and ND antibody vaccine titer in broiler chicks. Three hundred twenty one day old male broiler chicks(cobb ${\times}$ cobb) were divided into four levels of multiple probiotics(0, 0.1, 0.2, 0.3%) with five replicates for 35 days. Basal diets contained 21.5, 19.0% CP and 3,100 kcal/kg ME for starting and finishing period, respectively. Weight gain, feed intake and feed conversion were measured weekly. The number of Salmonella, E. coli, Lactobacillus, and yeast were examined from ileum and cecum at the end of experiment. ND vaccine titer, cholesterol were detected from sera. Weight gain of birds fed probiotics were 669.33, 679.75 at the level of 0.1 and 0.2% supplemental groups for starting period. It was also improved in those treatments for finishing period and higher than control for total period. Feed conversion tended to be improved compared to that of control by the supplementation of probiotics for the first three weeks and seemed to show the similar tendency for the rest of two weeks. It was 1.611, 1.621 for the entire feeding period and improved compared with control. Total salmonella, was not decreased in ileal digesta of birds fed the probiotics compared with control, whereas the number of yeast increased in 0.1% treatment. However, the number of Lactobacillus and yeast in cecum was higher than control. Even though the blood cholesterol seem to high in 0.1% probiotics treatment, the ratio of HDL to total cholesterol showed higher than control. ND vaccine titer of birds fed probiotics were significantly higher than control (P<0.05). These results 0.1% multiple probiotics would be possible to improve the performance of broiler chicks and ND vaccine titer.

• Journal of Ginseng Research
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• v.30 no.3
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• pp.128-131
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• 2006

Saponin isolated from red ginseng was added to cultures of Staphylococcus aureus and Candida albicans in order to investigate saponin's influence on the growth of some pathogenic bacteria and yeasts. S. aureus and C. albicans were incubated at $38^{\circ}C\;and\;28^{\circ}C$ for 5 days with 100 rpm after addition of 0.013, 0.125, 0.500 and 1.000% (w/v, final concentration) of saponin, respectively. After incubated for 1 day, 2 days or 5 days, pH and viable cell counts of the cultures were investigated. The both of pH of S. aureus and C. albicans were decreased in concentration-dependent manner. Viable cell counts after incubation of 5 days were $1.0\;{\times}\;10^8,\;9.4\;{\times}\;10^7,\;1.0\;{\times}\;10^3$ and 0 CFU/ml, respectively, when compared with $1.8{\times}10^8\;CFU/ml$ of saponin non-treated group. Especially, 1.0% concentration of saponin inhibited completely the growth of S. aureus. While, viable cell count in C. albicans somewhat lower values than that of saponin non-treated group, but the values not significant. These results suggest that ginseng saponin inhibit the growth of S. aureus in a concentration-dependent manner, but not the growth of C. albicans.