• KSBB Journal
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• v.10 no.3
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• pp.241-248
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• 1995

For the treatment of poorly biodegradable polyvinyl alcohol(PVA) in dye-processing wastewater, immobilized microbial beads were prepared by uslng agar-acrylamide method. PVA removal efficiency for the synthetic wastewater was 85% at the PVA volume loading rate of $3.1g/\ell$.day. In case of real desizing wastewater, PVA removal efficiency was 81.3% at the PVA volume loading rate of $3.25g/\ell$.day. In observation of cross section of immobilized bead passed 5 months with diameter of 2.4mm, the growth of cell was limited by the resistance of substrate and oxygen transfer for the inners region of more than 48% of bead radius from the surface. It was estimated that 70% of total removed PVA was degraded by the immobilized cells in the continuous immobilized reactor. Substrate utilization rate in the suspended reactor was decreased with increasing dilution rates above 0.083 hr-1, but that in the immobilized reactor was increased with increasing dilution rates up to 0.125hr-1. The substrate removal efficiency of immobilized reactor was much superior to that of suspended reactor with increasing dilution rates. Saturation constant of substrate utilization rate equation, Ks was $6.6 g PVA/\ell$, and maximum specific substrate utilization. k was 0.175g PVA/g cell.hr

• KSBB Journal
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• v.24 no.4
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• pp.377-382
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• 2009

The culture condition of growing Chlorella minutissima was optimized to produce biodiesel for fed-batch cultivation. First, under heterotrophic cultivation, the optimum level of glucose was determined to be 10 g/L for 20 days. After, three cultivation conditions were operated: autotrophic, heterotrophic, and mixotrophic growth. The lipid level and the maximum cell concentration from the fed-batch heterotrophic process were 32.0 (%, v/v) and 15.0 (g-dry wt./L) in 20 L flask, respectively. In addition, since the relatively constant specific lipid production rate was observed as 0.040 (% lipid/g-dry wt./day) at the latter period of cultivation time, the fed-batch process could maintain continuous lipid production. Fed-batch process is higher than those values from the batch process. The lipids from the fed-batch process contained over 38% of $C_{18}$, known as the suitable composition for the biodiesel application. For mixotrophic and heterotrophic growth under fed-batch condition, glucose was proved to be an appropriate carbon source for a large scale outdoor cultivation. For fed-batch cultivation, the feeding rate of seawater medium containing glucose was decided to be 0.5 L/day. The mixotrophic cultivation maintained maximum cell concentration of 24 (g-dry wt./L) and the lipid level of 43 (%, w/w). The lipid composition from this process was also proved to be suitable for the biodiesel production. The fatty acids from the mixotrophic growth contains 18% of $C_{17}$ and 49% of $C_{18}$, implying It also tells that C. minutissima is a suitable resource of biodiesel. Especially, the mixotrophic cultivation with fed-batch process might be useful for the large scale cultivation for the biodiesel production.

• Microbiology and Biotechnology Letters
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• v.44 no.1
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• pp.62-67
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• 2016

Hydrolytic enzyme activities, including those of ${\beta}$-glucosidase, ${\beta}$-glucuronidase, ${\beta}$-xylosidase, ${\beta}$-galactosidase, ${\beta}$-arabinofuranosidase, ${\beta}$-arabinosidase, and ${\beta}$-arabinopyranosidase, which are useful for bioconversion, were explored in lactic acid bacteria isolated from Korean traditional fermented foods. Nine bacterial strains were selected for the fermentation of green tea extract prepared by supercritical fluid extraction. Changes in the concentrations of catechin, epicatechin, epicatechin gallate, epigallocatechin, and epigallocatechin-3-gallate in green tea extract were investigated after fermentation by the selected lactic acid bacteria strains. The strain Leuconostoc mesenteroides MBE1424, which showed the highest ${\beta}$-glucuronidase enzyme activity among the tested bacterial strains, increased the epigallocatechin content of the green tea extract by 60%. In addition, L. mesenteroides MBE1424 was more resistant than the control strain at high temperature and showed a maximum specific growth rate at $40^{\circ}C$. L. mesenteroides MBE1424 was presumed to have an enzyme system containing ${\beta}$-glucuronidase with utility in the bioconversion of green tea extract.

• KSBB Journal
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• v.15 no.2
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• pp.134-138
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• 2000

Addition of carbon and nitrogen source to an alcohol distillery wastewater was tried to increase the cell concentration of a b baker's yeast cultivated in that wastewater. Carbon was found to be primary limiting nutrient and nitrogen secondary limiting o one. Glucose addition increased the cell concentration 1.3 times higher than no addition, and both glucose and $(NH_4)_2S0_4$ a addition did 5.8 times. A fed-batch cultivation by the automatic addition of glucose and ammonium was executed. Added g glu$\infty$se was automatically controlled to low concentration by a method using DO as control parameter. Ammonium was a automatically added as NH40H used as pH $\infty$ntrol agent after initiating glucose addition. By this simple cultivation method t the cell concentration $\infty$내d be efficiently increased from 2.6g/L to 12.0g/L, and maximum specific growth rate and biomass y yield to glu$\infty$se were $0.18hr^{-1}$ and about 0.54g/g respectively. By increasing cell concentration, COD of the wastewater m media could be additionally reduced by about 22%.

• KSBB Journal
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• v.15 no.2
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• pp.139-144
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• 2000

Automatic addition of glucose and ammonium to an alcohol distille깨 wastewater and the control of them at low $\infty$ncentration were tried to efficiently increase the cell concentration of a baker's yeast c비tivated in that wastewater. Added g glucose was indirectly controlled to less than 116 mg/L by a method which used DO as control parameter. Ammonium was a automatically measured and controlled within the range of 7.0~27.7 mM by a homemade on-line system which adopted FIA a as measurement method. Maximum specific growth rate and biomass yield to glucose were $0.21 hr^{-1}$ and about 0.78 g/g, w which were significantly increased values in contrast to those of an experiment without ammonium control. Biomass yield to a ammonium was 11.3 gIg. Cell cone엉ntration could be increased from 2.6 g/L to 18.5 g/L by the add ion of glucose and a ammonium.

• Journal of Powder Materials
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• v.26 no.3
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• pp.231-236
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• 2019

Ni hydroxides ($Ni(OH)_2$) are synthesized on Ni foam by varying the hexamethylenetetramine (HMT) concentration using an electrodeposition process for pseudocapacitor (PC) applications. In addition, the effects of HMT concentration on the $Ni(OH)_2$ structure and the electrochemical properties of the PCs are investigated. HMT is the source of amine-based $OH^-$ in the solution; thus, the growth rate and morphological structure of $Ni(OH)_2$ are influenced by HMT concentration. When $Ni(OH)_2$ is electrodeposited at a constant voltage mode of -0.85 V vs. Ag/AgCl, the cathodic current and the number of nucleations are significantly reduced with increasing concentration of HMT from 0 to 10 mM. Therefore, $Ni(OH)_2$ is sparsely formed on the Ni foam with increasing HMT concentration, showing a layered double-hydroxide structure. However, loosely packed $Ni(OH)_2$ grains that are spread on Ni foam maintain a much greater surface area for reaction and result in the effective utilization of the electrode material due to the steric hindrance effect. It is suggested that the $Ni(OH)_2$ electrodes with HMT concentration of 7.5 mM have the maximum specific capacitance (1023 F/g), which is attributed to the facile electrolyte penetration and fast proton exchange via optimized surface areas.

• Journal of Food Hygiene and Safety
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• v.36 no.6
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• pp.504-509
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• 2021

The objective of this study was to develop dynamic model to describe the kinetic behavior of E. coli in sliced smoked duck. E. coli was detected in 2 sliced smoked duck samples (16.7%) at 1.23 log CFU/g. The maximum specific growth rate (𝜇_max) of E. coli ranged from 0.05 to 0.36 log CFU/g/h, and lag phase duration (LPD) ranged from 4.39 to 1.07 h, depending on the storage at 10-30℃, and h₀ value ranged from 0.24 to 0.51. The developed model was validated with observed values obtained at 13℃ and 25℃. The model performance was appropriate with 0.130 of root mean squared error (RMSE), and the dynamic model also described properly kinetic behavior of E. coli in sliced smoked duck samples. These results indicate that E. coli can contaminate sliced smoked ducks and the models developed with the E. coli isolates are useful in describing the kinetic behavior of E. coli in sliced smoked duck.

• Korean Journal of Food Science and Technology
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• v.15 no.2
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• pp.177-182
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• 1983

Direct conversion of starchy materials to single cell protein of Sporobolomyces holsaticus FRI Y-5 was investigated. Effect of yeast extract concentration on its cell growth showed that it could utilize more of starch in the medium containing 2.5 g/l of yeast extract. In case of jar fermentor culture, the specific growth rate and cell yield of Sp. holsaticus on soluble starch were calculated to be $0.14\;hr^{-1}$ and 0.425, respectively and its maximum cell concentration was 13.4 g/l. After 80 hr of incubation time, 45.96% of starch was consumed and 45.1% of relative blue value was decreased. Reducing sugars in the starch medium seemed to increase from 4.06 g/l to 6.08 g/l and then to decrease. During fermentor culture, pH of medium was almost not changed in the range of $pH\;7.0{\pm}0.5$. The optimal temperature and pH of Sp. holsaticus amylase activity were $40^{\circ}C$ and pH 7.5, respectively. It was shown from the effect of Tapioca starch concentration on the cell growth that the optimal concentration of Tapioca starch for Sp. holsaticus was lower than that of soluble starch. FRI Y-5 cells settled much slower than Sp. holsaticus IFO 1032 cells and the viscosity vs cell concentration relationship was related to be linear.

• Journal of The Korean Society of Grassland and Forage Science
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• v.8 no.2
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• pp.110-116
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• 1988

The response of forage yield was studied with various growth indices to develop yield model and to determine optimum cutting time in three cultivars of orchardgrass. 1. Number of tiller per plant was the highest at 3rd cutting stage. But, it was decreased rapidly at 4th cutting stage. Leaf Area Index (LAI) was the highest at 3rd cutting stage. LAI was increased slowly during 15 days to 20 days after cutting and thereafter increased rapidly. 2. In dry matter yield over cutting stages, 1st cutting and 3rd cutting stages were higher yield than others. Change of dry matter yield was similar to that of LAI in all cutting stages. 3. Leaf Elongation Rate (LER) and Specific Leaf Weight (SLW) were reached to maximum at 20 to 25 days and 25 to 30 days after cutting, respectively. 4. Dry matte yield was highly correlated with LAI (r-0.905)and with CGR (r-0.962) over three cultivars. Also, LAI was significantly with LER. The best-fit yield model was obtained in multiple regression equation which included both dependent variables of LAI and CGR. 5. Optimum cutting times which were determined by the relationships between D.M. yield and LAI, and between D.M. yield and CGR, were ranged from 32 days to 36 days depend on each cutting stages.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.45 no.2
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• pp.146-153
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• 2012

This study examined the effect of formulated diets (composed of condensed freshwater $Chlorella$ or $Schizochytrium$ sp., $Crypthecodinium$ sp., and EPA oil sources derived from baker's yeast) on the population growth and fatty acid composition of the brackish water flea ($Diaphanosoma$ $celebensis$) to determine diet effectiveness for mass production. Results indicated that the highest maximum density, fecundity, and population specific growth rate (SGR) of the flea were observed using a diet of $Tetraselmis$ $suecica$ (control). However, results using condensed freshwater $Chlorella$ and the mixed treatment of $Schizochytrium$ sp.+$Crypthecodinium$ sp.+EPA oil did not significantly differ from the control treatment ($P$>0.05). Thus, $T.$ $suecica$ could be replaced with a combination diet of $Schizochytrium$ sp., $Crypthecodinium$ sp., and EPA oil in condensed freshwater $Chlorella$ without growth interruption of $D.$ $celebensis$. As the percentage of combination diet (mix of $Schizochytrium$ sp., $Crypthecodinium$ sp., and EPA oil) in condensed freshwater $Chlorella$ increased, the level of ARA, EPA, DHA, and n-3 HUFA in $D.$ $celebensis$ also increased. However, the population density of $D.$ $celebensis$ sharply decreased with the use of treated supplements C5M5 (CHL [50%] and $Crypthecodinium$ sp.+ $Schizochytrium$ sp. + EPA oil [MIX 50%]). The optimum proportions of CHL and MIX for $D.$ $celebensis$ within the mixture were 70% and 30%, respectively. Based on the results, the combination of $Schizochytrium$ sp., $Crypthecodinium$ sp., and EPA oil in condensed freshwater $Chlorella$ appears to be a stable and effective food source for mass production of $D.$ $celebensis$.