• Microbiology and Biotechnology Letters
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• v.13 no.2
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• pp.115-118
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• 1985

Rifamycin B oxidase converts rifamycin B to rifamycin S using oxygen as cosubstrate. Humnicola spp. (ATCC 20620) was treated with acetone and the cell powder was immobilized with cellulose acetate. The properties of the immobilized enzyme was examined. The optimum pHs of the immobilized and the free enzymes were 7.2. The optimum temperature of the immobilized enzyme was at 50-55$^{\circ}C$, which was 5$^{\circ}C$ higher than that of the free enzyme. The activities of the immobilized enzyme appeared less sensistive with respect to the changes of temperature and pH as compared to those of the free enzyme. Twenty percent of the enzyme activity was recovered when the enzyme was immobilized in 3mm beads. The storage stability was good below 4$0^{\circ}C$, but the activity decreased very rapidly above 5$0^{\circ}C$. The physical strength of the beads was good and was suitable as packing material in a three-phase enzyme reactor.

• Microbiology and Biotechnology Letters
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• v.32 no.2
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• pp.154-157
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• 2004

Immobilized cells of Aspergillus niger was employed to produce citric acid by fermentation of milk factory waste water. A. niger ATCC 9142 as a citric acid production strain was cultured for 3 days and was entrapped with Ca-alginate bead about 2.5∼3.5 mm. The optimal pH and temperature were estimated to be 3.0 and $30^{\circ}C$, respectively. Dilution rate for fermentation was calculated to be $0.025 h^{－1}$ . Maximum amount of citric acid was obtained at 4.5 g/$\ell$ with the optimized fermentation condition. The yield of citric acid produced by immobilized A. niger ATCC 9143 was 70.3%. The yield was increased by 20% with immobilized cell, compared to that of the shake flask culture. Hence, the milk factory waste water is worthy to be used for the substrate of citric acid fermentation.

• KSBB Journal
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• v.4 no.2
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• pp.110-117
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• 1989

The fiffusion characteristics of substrate of varing biomass concentrations into and from Ca- alginate gel beads in well-stirred solutions were investigated. Ca-alginate gel beads were immobilized by Zymomonas mobilis or free from cells. The values of the diffusion coefficient of substrate were calculated by means of the method of Least squares and Random pore model. Reaction rates are expressed by the Michaelis-Menten type equation, and the results are compared with experimental data. Intraparticle effective diffusivity of substrate resistance on reaction by using immobilized Z.mobilis entrapped by Ca-alginated gel seemed to be restricted by cell density. The experimental data also indicated relationship between the effective diffusivity and the cell concentration used in the gel preparation.

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.431-434
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• 2002

Effect of various factors on the phenol degradation by activated sludge immobilized with the photocrosslinked resin were investigated. The optimum pH on the degradation of phenol in both free and immobilized activated sludge was 7. A higher rate of phenol degradation was observed when a bead size, vas smaller. The phenol degradation in the free activated sludge was inhibited at the 3000 mg/L of phenol, while that in the immobilized activated sludge was maintained at the same concentration for 28 hrs without an inhibition.

• Microbiology and Biotechnology Letters
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• v.15 no.2
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• pp.122-128
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• 1987

Lipases from Candida rogosa and Rhizopus arrhizus were immobilized by entrapment with photo-crosslinkable resin prepolymer for the study of fat splitting and interesterification in isooctane-two phase system. Dioctylsulfosuccinate was selected as the most suitable surfactant during the immobilization. Lipase entrapped with hydrophobic photo-crosslinkable resin prepolymer(ENTP-3000) exhibited the highest activity, whereas lipase entrapped with hydrophilic gel(ENT-4000) was more stable in organic solvent. As the degree of hydrophobicity of the immobilization matrix was increased, Vm(app) of the lipase entrapped was increased, but Km(app) was approximately constant. While the optimum pH of the lipases entrapped on hydrophilic gel (ENT-4000) were around pH 7.0 for Candida lipase and Rhizopus lipase, the reaction rate of the lipases entrapped on hydrophobic gel were less dependent on pH variations for short reaction time. However, for longer reaction time, the lipnses from C. rugosa and R. arrhizus entrapped on hydrophobic gel yielded maximum rate at pH 6.0 and 6.5, respectively, Entrapment method endowed the lipase with thermal stability.

• Korean Journal of Food Science and Technology
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• v.20 no.2
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• pp.245-251
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• 1988

Thermolysin was immobilized on Dowex MWA-1 with 10% glutaraldehyde and incorpo rated into a fluidized-bed continuous coagulation scheme to make Cheddar type cheese. The activity yield of thermolysin was 25%. The immobillized thermolysin was stable at $60^{\circ}C$ in the presence of 1/200M calcium ions and the half-life value is 16 days at the temperature. Raw milk alkalified to pH 7.0 was passed through a column of thermolysin beads at $55^{\circ}C$, cultivated with Streptococcus cremoris and allowed to coagulate. A typical milk curd was formed to make Cheddar type cheese, avoiding troublesome microbial contamination successfully during continuous hydrolysis process. During ripening of this cheese for 6 months at $10^{\circ}C$, its ripening ratio and taste were similar to those of cheese prepared by the traditional method.

• Microbiology and Biotechnology Letters
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• v.25 no.1
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• pp.106-108
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• 1997

Blue green algaes (NIES 19, 39, 46) have been cultivated to product sigle cell protein. After 7 days of cultivation under 5000 (W/M$^{2}$) of ligth intensity, final cell concentration was 2.8 (g/L) and chlorophyll a was 4.9 (mg/L). When initial concentration of NaHCOC was 1.7% and NaNO$_{3}$ was0.25%, maximum cell concentration was obtained. Spirulina platensis NIES 39 showed faster growth rate than NIES 46. While most 39 sedimented, most 46 floated.

• Microbiology and Biotechnology Letters
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• v.24 no.4
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• pp.500-506
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• 1996

Bacillus subtilis SH-1 screened from coastal sea water of South Korea was used to produce bacteriolytic enzyme. The production of bacteriolytic enzyme by immobilized cells was investigated. The optimum conditions for the continuous production of the bacteriolytic enzyme using immobilized cells were 2.4 mm diameter of 0.3% alginate beads, 20 ml/h of substrate feeding rate and 20 l/min of aeration rate. A productivity of 76.5 to 88.0 units/ml could be obtained for 25 days by continuous column reactor under the optimum conditions.

• Microbiology and Biotechnology Letters
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• v.20 no.6
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• pp.704-706
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• 1992

A model peptide, N-carbobenzoxy-L-phenylalanyl-L-phenylalanine methyl ester, was synthersized with free and immobilized thermolysin in a microaqueous system. The model peptide was formed mostly during the initial phase of the reaction. The yields of the compound with free and immobilized thermolysin after 4hr of reaction were 77.8 and 71.2, respectively.

• Microbiology and Biotechnology Letters
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• v.17 no.6
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• pp.629-633
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• 1989

In the continuous reactor, the hydrogen production rate and residual glucose concentration were increased with increase of input glucose concentration, dilution rate, and recycle rate. The maximum production rate was 91 mL/Lㆍh at dilution rate 0.4/h, input glucose concentration 5.4g/L, and recycle rate 70/h in this experimental range.