• Biotechnology and Bioprocess Engineering:BBE
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• v.6 no.1
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• pp.42-50
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• 2001

The activity of immobilized cell-support particle aggregates is influenced by physical and biochemical elements, mass transfer, and physiology. Accordingly, the mathematical model discussed in this study is capable of predicting the steady state and transient concentration profiles of the cell mass and substrate, plus the effects of the substrate and product inhibition in an immobilized cell-support aggregate. The overall mathematical model is comprised of material balance equations for the cell mass, major carbon source, dissolved oxygen, and non-biomass products in a bulk suspension along with a single particle model. A smaller bead size and higher substrate concentration at the surface of the particle, resulted in a higher supply of the substrate into the aggregate and consequently a higher biocatalyst activity.

• Journal of Environmental Health Sciences
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• v.18 no.1
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• pp.84-94
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• 1992

In an attempt to develop the immobilized biocatalysts based on immobilized Saccharomyces cerevisiae, immobilized yeast was investigated with respect to the conditions affected to ethanol productivities. Saccharomyces cerevisiae was immobilized in the form of the beads by magnetic-calcium alginate, non magnetic-calcium alginate and acrylamide polymerization. Magnetic immobilized yeast, nonmagnetic immobilized yeast and polyacrylamide immobilized yeast were compared in respect of their pH stability, thermostability, heat tolerance, the relation between the concetration of native yeast and retained activity of immobilized yeast, the activity depending on bead size of immobilized yeast, and the effects of magnesium and cobalt on the activities. The more small bead had retained the higher activity for the three kinds of immobilized yeast. In case of 1.0mm diameter of beads, the retained activity was 40~50% for the all groups. The pH stability profile for the immobilized yeast showed a broad range of optimun activity while the native yeast gave a sharp pick for its optimun pH value. The thermostability was at the range of 25~55$^{\circ}$C for the immobilized yeast groups. It was investigated that the influent magnesium and cobalt concentration, and the relative activity have an influent on heat tolerance at steady state. Both protein content released from immobilized yeast and activity of immobilized yeast were changed after activation of immobilized yeast cell.

• Journal of Life Science
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• v.11 no.3
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• pp.273-278
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• 2001

Removal of nitrogen compound from waste water is essential and often accomplished by biological process. Deni-trification bacterium. Paracoccus denitrificans(KCTC 2350) is employed to estimate the ability and the characteristics of denitrification. In the immobilized biological reactor system, the measurement of absolute amount of active strain in the reactor is comparatively difficult or impossible. In this study, strain immobilized denitrification reactor was designed with the unwoven texture wrapped peeped hole plastic tube to calculated the absolute amount of active strain by comparing the activity of the immobilized reactor adn the free cell reactor. The reactor system was continuous stirred tank reactor and the rate of substrate consumption was assumed to be Michaelis-Menten equation. As a result, we found that the amount of immobilized active strain was the half of the total active strain in the reactor and the time required to reach in the equilibrium state in the immobilized reactor system was shorter than that of the free cell reactor system.

• KSBB Journal
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• v.9 no.2
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• pp.200-210
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• 1994

In batch bioreactor fermentations for cyclosporin A (CyA) production, good potential for bioprocess improvement was demonstrated in the immobilized cell system, providing appreciably better utilization of the catalytic activity of the biomass than the freely suspended cells, especially during the exponential phase. When concentrated nutrient medium was added pulsely during the exponential phase of cell growth(at hour 139 of fermentation), reactivation and regermination in both immobilized and suspended cell cultures were observed to contribute to the longevity of CyA production, maintaining maximum CyA titre until 250 hours of fermentation. Contrarily, simple batch fermentations without any supplement of medium in both systems showed repid decrease in CyA concentrations during the late stationary phase. Notably, the CyA yield coefficient $(Y_p/x)$ for the immobilized cell system was maintained quite high even after the pulse addition of the concentrated full medium, reaching almost 80% of the level attained during the exponential phase. This is in sharp contrast when compared with the corresponding value of 58% in the case of parallel-suspended cells. This pattern of CyA production resulted in considerably enhanced CyA production in the immobilized cell system, reaching almost 2 time higher maximum CyA production in comparison with the free cell system.

• Journal of Microbiology and Biotechnology
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• v.12 no.4
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• pp.557-562
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• 2002

Physiological characteristics such as specific productivity, morphology of Streptomyces cells Immobilized on celite beads, and operational stability at different dilution rates were investigated in continuous immobilized-cell cultures for the production of kasugamycin. At a dilution rate (D) of 0.05 $h^{-1}$, a relatively high specific productivity was attained and the loss of cell-loaded beads was negligible. At D=0.1 $h^{-1}$, a higher specific productivity and cell concentration could be obtained, resulting in a significantly improved volumetric kasugamycin productivity. However, no stable operation could be maintained due to a significant loss of cell-loaded beads from the reactor that was caused by their fluffy morphology developed in the later stage. At D=0.2 $h^{-1}$, the production of kasugamycin and cell growth were observed to be severely inhibited by the high concentration of residual maltose.

• Journal of Environmental Health Sciences
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• v.17 no.1
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• pp.120-128
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• 1991

Saccharomyces cerevisiae was immobilized by incubating iron oxides with calcium alginate, and by polyacrylamide entrapment to use repeatedly for the conversion of glucose to ethanol. Magnetic and non-magnetic immobilized yeast and polyacrylamide immobilized yeast were compared with the native yeast a batch-fermentation of ethanol from glucose. Three kinds of immobilized yeast tended almost identically, having ethanol productivity as well as the final yield about the same to what was found for the native yeast. The long-term operational stability of three kinds of immobilized yeast were significant difference according as immobilized yeast activation or non-activation before ethanol fermentation. In the non-activation they lost their activity of fermentation rapidly in the beginning stage an slower at a later stage. On the other hand, in the activation with nutrient media, their activities were increased to some extent and stable in the later stage. The cell count of three kinds of immobilized yeast after activiation by incubating nutrient media, increased by a factor of about 45 to 48, whereas the fermenting capacity increased by a factor of 174 to 178. In the prearation of immobilized biocatalysts, magnetic matter does not seem to have any adverse affect on the properties of the microorganism. The immobilized biocatalysts by utilizing magnetic matter have some advantages, especially in application of viscous media or insoluble particle-containing media, for this work was linked with microbial utilization of environmental wastes and elimination of envirnmental pollutant.

• Journal of Microbiology
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• v.44 no.3
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• pp.354-359
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• 2006

This study examined the capacity of immobilized bacteria to degrade petroleum hydrocarbons. A mixture of hydrocarbon-degrading bacterial strains was immobilized in alginate and incubated in crude oil-contaminated artificial seawater (ASW). Analysis of hydrocarbon residues following a 30-day incubation period demonstrated that the biodegradation capacity of the microorganisms was not compromised by the immobilization. Removal of n-alkanes was similar in immobilized cells and control cells. To test reusability, the immobilized bacteria were incubated for sequential increments of 30 days. No decline in biodegradation capacity of the immobilized consortium of bacterial cells was noted over its repeated use. We conclude that immobilized hydrocarbon-degrading bacteria represent a promising application in the bioremediation of hydrocarbon-contaminated areas.

• Journal of environmental and Sanitary engineering
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• v.11 no.2
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• pp.1-7
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• 1996

The behavior of total organic carbon (TOC) and phosphate were observed for 15 days with immobilized activated sludge using polyacrylamide (PAA) by sequencing batch reactor (SBR). In the preparation of immobilized sludge by PAA, it was found that suitable acrylamide concentration for actual wastewater treatment was to be 15% through the batch test. When SBR system was operated in the repeated aerobic and anaerobic conditions, TOC removal efficiency was 92%. The uptake rate of phosphate was increased from 1.78 mg-P/g cell/hr on the 5th day of acclimation to 2.5 mg-P/g cell/hr on the 15th day of acclimation. And the total phosphorus content in PAA bead was increased from 40 mg-P/g cell on the 1st day of operation to 55 mg-P/g cell on the 15th day of operation. From this study, lowering the volume of aeration tank was possible when PAA bead was used in wastewater treatment and long operation was also possible without the settler.

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.53-56
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• 2002

Mammalian cell based biosensor kits are expected to be in assessment of samples toxicity more sensitive and accurate. A recombinant fluorescent Chinese Hamster Ovary (CHO) cell line was known to be responsive to the various toxicants Specially. KFC- AlO cell line. which contain the c-fos SRE::GFP plasmid (pKFG). was found to be able to detect toxicants sensitively. A biosensor kit was developed by using an immobilized KFC-A10 cell line. Immobilized recombinant fluorescent cells within agarose, known as a representative hydrogel matrix, have been maintained in the matrix viably and have shown constant fluorescent levels for long time. Immobilized cells have shown the ability to detect the chemical toxicity in the keep of fluorescent level as the metabolism is inhibited under toxic conditions.

• KSBB Journal
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• v.25 no.4
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• pp.351-356
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• 2010

To increase the production of ethanol by using sugar from lignocellulosic biomass, pentose and hexose have to be fermented simultaneously by yeast. The effects of mixed sugar and nitrogen on ethanol production by immobilized Pichia stipitis KCCM 12009 were investigated. When optimal mixed sugar and nitrogen concentration were 5% (Glucose/Xylose = 3:1) and 1%, respectively, ethanol concentration produced by immobilized P. stipitis was 19-20 g/L. In repeated fed-batch by immobilized P. stipitis, all glucose was consumed very quickly at 1-3% mixed sugar concentration. But, xylose consumption was decreased as the mixed sugar concentration increased. Also, ethanol (5.6 g/L) was stably produced and ethanol production rate was 0.13 g/$L{\cdot}h$ in immobilized cell reactor (ICR) with 1% mixed sugar (Glucose/Xylose = 3:1) as feeding media.