• Biotechnology and Bioprocess Engineering:BBE
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• 제7권4호
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• pp.194-200
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• 2002

The cells of Rhodococcus rhodochrous M33, which produce a nitrile hydratase enzyme, were immobilized in acrylamide-based polymer gels. The optimum pH and temperature for the activity of nitrile hydratase in both the free and Immobilized cells were 7.4 and 45$\^{C}$, respectively, yet the optimum temperature for acrylamide production by the immobilized cells was 20$\^{C}$. The nitrile hydratase of the immobilized cells was more stable with acrylamide than that of the free cells. Under optimal conditions, the final acrylamide concentration reached about 400 g/L with a conversion yield of almost 100% after 8 h of reaction when using 150 g/L of immobilized cells corresponding to a 1.91 g-dry cell weight/L. The enzyme activity of the immobilized cells rapidly de-creased with repeated use. However, the quality of the acrylamide produced by the immobilized cells was much better than that produced by the free cells in terms of color, salt content, turbidity, and foam formation. The quality of the aqueous acrylamide solution obtained was found to be of commercial use without further purification.

• Journal of Microbiology and Biotechnology
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• 제12권5호
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• pp.766-772
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• 2002

The plasmid, pJHKJ4, containing the endoxylanase gene, was introduced into Bacillus subtilis DB 104. The recombinant cells produced 587 unit/ml of endoxylanase at 33 h. The endoxylanase was immobilized covalently on the surface of silica fur effective xylan hydrolysis. The activities of the immobilized and free endoxylanases were optimal at pH 6.5 and 10 mM $MnSO_4$. The optimal temperature of the immobilized endoxylanase was $60^{\circ}C$, whereas that of the free endoxylanase was $65^{\circ}C$. Under these optimal conditions, the activity of the immobilized endoxylanase was 1.7 times higher than that of the fee endoxylanase. From microscope photographs, the immobilized endoxylanase was found to be bounded and evenly distributed on the surface of silica, a nonporous solid support. The enzyme kinetics between the immobilized and free endoxylanases was estimated to be uncompetitive, when plotting double-reciprocal plots against xylan concentrations and endoxylanase activities. These results suggest that the higher activity of the immobilized endoxylanase may be due to increased formation of enzyme-substrate complex, because of the easy accessibility of the immobilized enzyme to the polysaccharide-xylan as a high molecular weight substrate.

• Journal of Periodontal and Implant Science
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• 제36권3호
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• pp.627-637
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• 2006

이 연구는 rh BMP-7-immobilized substrates에 대한 백서 태자 두개관 세포의 반응을 석회화 결절 측정, 알카리 효소 분석, 역전사 중합반응 및 단백질 분석등으로 평가하여 다음과 같은 결과를 얻었다. 1. 배양 14일 째, 석회화 결절 형성율을 측정한 결과, rh BMP-7-immobilized substrates에서 대조군과 비교하여 더 많은 석회화 결절을 형성하였다. 2. 배양 7일에 염기성 인산 분해효소 활성도는 rh BMP-7-immobilized substrates에서 대조군에 비해 효소 활성도가 유의하게 높았다. 3. 역전사 중합반응의 결과에서 BSP 와 OCN 유전자 발현은 대조군보다 더 현저하였다. 4. 단백질 분석에서 rh BMP-7-immobilized substrates와 대조군 모두 Smad 1,5,8 단백질의 인산화를 활성화시키지 못했다. 이상의 결과 rh BMP-7-immobilized substrates는 백서 태자 두개관세포가 조골세포로의 분화와 석회화를 유도하며 따라서 rh BMP-7-immobilized substrates는 임프란트 주변의 골 형성에 유용하리라 사료된다.

• KSBB Journal
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• 제13권4호
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• pp.411-417
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• 1998

The possibility of application of membrane type immobilized adsorbent to the fed-batch or perfusion culture system with anchorage-independent cells as well as batch system was investigated. The improvement in cell density and cell viability due to the combination of immobilized adsorbent with each culture system was evaluated for the investigation, and the optimum culture system employing immobilized adsorbent system was suggested based on the results. It was observed that the system with immobilized adsorbent showed better cell growth and cell viability than that without immobilized adsorbent in every operation system of batch, fed-batch, and perfusion. In case of batch system, 200% improvement of maximum cell density was observed in the system where ammonium chloride was added on purpose. And 50% improvement of maximum cell density was observed in the fed-batch system where ammonium ion accumulates significantly, while small increase in maximum cell density was observed in the perfusion system where dilution of waste byproducts exists. Especially, the fed-batch system showed the most significant improvement on cell growth because both compensation of nutrient and removal of ammonium ion occurred simultaneously in the system. Therefore a combined system of immobilized adsorbent and fed-batch operation could be suggested as an optimum system with in situ removal of ammonium ion.

• Bulletin of the Korean Chemical Society
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• 제1권1호
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• pp.10-17
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• 1980

Penicillin amidohydrolase was partially purified from the fermented broth of Bacillus megaterium, and was immobilized on nylon fiber. The surface area of nylon fiber was increased by roughening it with fine sand and activated by acid treatment. The free amino groups on the nylon fiber exposed by such treatment were then utilized to immobilize the penicillin amidase. Enzymatic properties of penicillin amidohydrolase immobilized on the nylon fiber by covalent bonding and cross linking with glutaraldehyde were studied and compared with those of soluble enzyme. The optimal pH and temperature profile of immobilized enzyme showed only slightly broader peaks, and the values of kinetic constants, $K_m$, $K_{ia}$, and $K_{ip}$, of the immobilized enzyme are only slightly greater than those of the soluble enzyme. These results suggest that the mass transfer effect on the reaction rate for the penicillin amidase immobilized on nylon fiber is not so significant as the enzyme immobilized on some other support material like bentonite. The experimental results of batch reaction agreed well with the results of computer simulation for both the immobilized and soluble enzyme systems, confirming the validity of the rate equation derived which was based on the combined double inhibition by two reaction products.

• 한국미생물·생명공학회지
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• 제24권6호
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• pp.705-711
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• 1996

For the efficient production of 2, 5-diketo-gluconic acid (2, 5-DKG) by the immobilized cells of Erwinia herbicola, basic characteristics of 2, 5-DKG fermentation were analyzed and a process employing immobilized cell reactor was developed. The immobilized cells appeared to have diffusion limitation, and a maximum production of 2, 5-DKG was accomplished with 2 mm diameters of immobilized beads. Long-term stabilities of the immobilized cells could be maintained by addition of 1.75% (w/v) polypep- tone. Repeated batch fermentations with about 80 mol% of 2, 5-DKG yields were carried out six times in the fluidized bubble column reactors filled with immobilized cells at an aeration rate of 6 vvm.

• Journal of Microbiology and Biotechnology
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• 제7권2호
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• pp.151-156
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• 1997

Two commercially available lipases, Lipase OF (non-specific lipase from Candida rugosa) and Lipolase 100T (1, 3-specific lipase from Aspergillus niger), were immobilized on insoluble hydrophobic support HDPE (high density polyethylene) by the physical adsorption method. Hydrolysis performance was enhanced by mixing a non-specific Lipase OF and a 1, 3-specific Lipolase 100T at a 2 : 1 ratio. The results also showed that the immobilized lipase maintained its activity at broader temperature ($25~55^{\circ}C$) and pH (4-8) ranges than soluble lipases. In the presence of organic solvent (isooctane), the immobilized lipase retained most of its activity in upto 12 runs of hydrolysis experiment. However, without organic solvent in the reaction mixture, the immobilized lipase maintained most of its activity even after 20 runs of hydrolysis experiment.

• 한국미생물생명공학회:학술대회논문집
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• 한국미생물생명공학회 1979년도 추계학술대회 심포지움
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• pp.245.2-246
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• 1979

Heat treated whole cell of Aspergillus niger containing glucose oxidase-catalase system was entrapped in gelatin matrix crosslinked by glutaral-dehyde. The reaction characteristics of immobilized enzyme was studied in a fludized reactor. Heat treatment enhanced the stability and improved the properties of micellium for the immobilized process. The immobilized enzyme system showed the maximum activity at $35^{\circ}C$ and at pH 5.5. The optimum substrate concentration was 0.04M glucose. The activity of immobilized glucose oxidase was in proportion to the concentration of dissolved oxygen in reaction mixture as other reaction conditions were fixed. It was also demonstrated that the limiting factor for the activity of the immobilized glucose oxidase was the oxygen diffusion resistance which increases proportionally to the glucose concentration.

• Journal of Microbiology and Biotechnology
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• 제17권4호
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• pp.650-654
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• 2007

In our previous work, a method of pretreating lipase was developed to prevent loss of its activity during covalent immobilization. In this study, Rhizopus oryzae lipase was pretreated before immobilization and then immobilized on a silica gel surface. The effects of the various materials and conditions used in the pretreatment stage on the activity of immobilized lipase were investigated. Immobilized lipase pretreated with 0.1% of soybean oil had better activity than those pretreated with other materials. The optimal temperature, agitation speed, and pretreating time for lipase pretreatment were determined to be $40^{\circ}C$, 200rpm, and 45min, respectively. The activity of immobilized soybean oil pretreated lipase was 630U/g matrix, which is 20 times higher than that of immobilized non-pretreated lipase. In addition, immobilized lipase activity was maintained at levels exceeding 90% of its original activity after 10 reuses.

• 환경위생공학
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• 제13권1호
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• pp.174-184
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• 1998

Biosorption characteristics were investigated to discuss the use of agar entrapped Spirulina to remove of heavy metal ions from polluted waters. Agar immobilized algae were used as bioadsorbent in continuous reactor for heavy metal ions removal. The process solution contains Pb, Cu, and Cd as single ion and binary ions. In the adsorption of single heavy metal ions by agar immobilized Spirulina, the adsorption reached within 1hr and observed diffusion limitation differed from the free algal cell adsorption. The optimum pH for the adsorption of heavy metals was 4.5 but the influence of pH decreased less than that of free algal cell. Also, the adsorption characteristics of single heavy metal ions with agar immobilized Spirulina fitted the BET isotherm. Both of experiments of free algal cell and agar immobilized algae showed higher removal efficiency in the single ion solutions than binary ions solutions. The experimental results in the packed column with agar immobilized algae were over 90% of removal efficiency for the Pb, Cu, and Cd in single ion solutions.