• Journal of Microbiology and Biotechnology
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• 제17권9호
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• pp.1430-1436
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• 2007

[ ${\alpha}$ ]-Galactosidase was immobilized in a mixture of k-carrageenan and locust bean gum. The properties of the free and immobilized enzyme were then determined. The optimum pH for both the soluble and immobilized enzyme was 4.8. The optimum temperature for the soluble enzymes was $50^{\circ}C$, whereas that for the immobilized enzyme was $55^{\circ}C$. The immobilized enzyme was used in batch, repeated batch, and continuous modes to degrade the raffinose-family sugars present in soymilk. Two hours of incubation with the free and immobilized ${\alpha}$-galactosidases resulted in an 80% and 68% reduction in the raffinose oligo saccharides in the soymilk, respectively. In the repeated batch, a 73% reduction was obtained in the fourth cycle. A fluidized bed reactor was also designed to treat soymilk continuously and the performance of the immobilized ${\alpha}$-galactosidase tested at different flow rates, resulting in a 90% reduction of raffinose-family oligosaccharides in the soymilk at a flow rate 40 ml/h. Therefore, the present study demonstrated that immobilized ${\alpha}$-galactosidase in a continuous mode is efficient for reducing the oligosaccharides present in soymilk, which may be of considerable interest for industrial application.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2003년도 생물공학의 동향(XII)
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• pp.116-120
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• 2003

Type strain, Methylosinus trichosporium OB3b, was used to convert methane to methanol. To prevent further oxidation of methanol, NaCl and EDTA were used as inhibitors of methanol dehydrogenase. The reaction temperature was $25^{\circ}C$, and the concentrations of cell and sodium formate added to the reaction mixture were 0.6 mg dry cell wt/ml and 20 mM, respectively. During 12hr reaction, 8 mM methanol was accumulated in the reaction mixture. In this reaction $K_m$ and $V_{max}$ values were found to be 532.6 mM and 1.749 mmol/hr, respectively, and the conversion rate was approximately 37%. To increase the concentration of methanol in the medium, a repeated batch reaction was carried out. In this process, methane was injected every eight hours, and the produced methanol concentration was 18 mM.

• Mycobiology
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• 제42권3호
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• pp.305-309
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• 2014

We investigated a novel process for production of ethanol from glycerol using the yeast Pachysolen tannophilus. After optimization of the fermentation medium, repeated-batch flask culture was performed over a period of 378 hr using yeast cells immobilized on Celite. Our results indicated that the use of Celite for immobilization of P. tannophilus was a practical approach for ethanol production from glycerol, and should be suitable for industrial ethanol production.

• 한국미생물·생명공학회지
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• 제17권6호
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• pp.624-628
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• 1989

A study on the citric acid production using Saccharomycopsis lipolytica (NRRL Y7576) was carried out in shake-flasks, air-lift and membrane recycle bioreactors. The cells entrapped in Ca-alginate beads were used in shake-flasks and air-lift reactor. Repeated batch fermentation in shake-flasks was successfully performed for 34 days and resulted in a yield of 54%. Increased yield (63%) was obtained in the air-lift reactor operation using nitrogen deficient medium (NDM). In the membrane recycle bioreactor operation, the maximal dry cell mass concentration was 39 g/1 at a dilution rate of 0.02 h$^{-1}$ and the yield with NDM was higher than that with growth medium. In addition, the yield and volumetric productivity with pure oxygen supply were greatly improved compared with those with air supply.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 추계학술발표대회 및 bio-venture fair
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• pp.329-331
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• 2000

A marine bacterium, Pseudomonas aeruginosa BYK-2 KCTC 18012P was immobilized in modified polyvinyl alcohol for the continuous production of rhamnolipids. The stability of rhamnolipids production, the mechanical strength of beads and the scanning electron microscope of immobilized cell were determined in a repeated batch culture. The rhamnolipids production was maintained $80{\sim}90%$ stability of initial production, and the mechanical strength also was stable during the repeated batch culture more than 14 cycles. In the case of SEM studies, the internal distribution pattern of the cell entrapped in modified PVA beads was observed. On the basis of optimal conditions, the continuous culture was investigated in 1.8L air lift bioreactor. The result suggested 0.1g/h rhamnolipids was obtained from 1%(v/v) fish oil continuously in conditions of 1.2L working volume, 0.5vvm and 20ml/h flow rate.

• Biotechnology and Bioprocess Engineering:BBE
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• 제11권6호
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• pp.544-549
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• 2006

The performance of immobilized fungal cells on celite beads for the production of gibberrelic acid was investigated in flasks and 7-L stirred-tank reactor. Repeated incubations of immobilized fungal cells increased cell concentrations and volumetric productivity. The maximum volumetric productivity obtained in the immobilized-cell culture was 3-fold greater than that in suspended-cell culture. The concentration of cotton seed flour (CSF), among the various nutrients supplied, most significantly influenced productivity and operational stability. Notably, insoluble components in CSF were found to be essential for production. CSF at 6 g/L with 60 g/L glucose was found to be optimal for gibberellic acid production and stable operation by preventing excessive cell growth.

• KSBB Journal
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• 제25권2호
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• pp.179-186
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• 2010

응집성 효모인 S. cerevisiae ATCC 96581를 이용한 최적의 에탄올 생산 공정 전략에 대하여 연구하였다. 효모의 특성을 고려하여, 효모 응집공정이 있는 반복 유가식 공정을 설계하였고, 이때 비멸균 포도당 분말을 매 12시간 마다 첨가하였고, 새로운 feeding medium을 24시간 혹은 36시간마다 세포 응집 후 교체 하였다. 이때 효모 응집이 없는 반복 유가식 공정과 비교 검토하였다. 최종적으로 24시간마다 세포를 응집시키고 상층배지를 제거하고 새로운 배지를 넣으면서 반복 유가식 에탄올 생산을 하는 것이 최적의 조건임을 알 수 있었고, 이때 120시간 동안 825 g의 에탄올을 생산 할 수 있었다.

• 한국균학회지
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• 제39권3호
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• pp.243-248
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• 2011

6탄당과 5탄당을 이용할 수 있는 효모 Picha stipitis를 이용하여 해조류인 구멍갈파래 가수분해 추출물의 단당류로부터 바이오 에탄올을 생산하는 반복 회분식 공정에 대하여 연구하였다. 이러한 공정이 180시간 까지 반복적으로 이루어질 수 있었으며, 약 30 g/L의 총환원당으로 부터 최고 평균 11.9 g/L의 바이오 에탄올이 생산됨을 확인하였다. 이 때 바이오 에탄올 수율은 0.40 (DNS 방법 기준)과 0.37 (TLC 방법 기준)이었으며, 이는 이론치의 78.4%와 72.5%에 해당하는 바이오 에탄올 수율에 해당한다. 이 결과를 다른 측면에서 분석하면, 본 연구 결과로 얻어진 반복 회분식공정에서 건조 구멍갈파래 1 kg에서 39.67 g의 바이오 에탄올을 생산 할 수 있다는 결론을 얻게 되었다. 본 연구를 통하여 구멍갈파래의 가수분해 추출물로부터 바이오 에탄올을 생산할 수 있다는 것을 실험적으로 증명하였고, 상업적인 대량생산이 가능한 공정기술로서 반복 회분식 방법이 적합하다는 것을 확인할 수 있었다.

• Applied Biological Chemistry
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• 제38권1호
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• pp.26-30
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• 1995

돼지감자 분말을 원료로 alginate에 고정화된 Kluyveromyces marxianus FO43의 에탄올 생산성을 향상시키기 위한 연구를 수행하였다. 15% 돼지감자 배지에서 발효시킨 고정화 효모에 의한 에탄올 농도와 이론치에 대한 에탄올 수율은 4일 후에 각각 3.38%(w/v), 54.20%로 이것은 고정화하지 않은 효모의 3.76%(w/v), 71.13% 보다 낮았다. Cellulase의 첨가는 $15{\sim}20%$ 돼지감자 배지의 점조성을 크게 낮추어 고정화 효모의 에탄올 생산성을 증가시켰다. 그리하여 20% 배지에서도 효소를 처리하여 고정화 효모를 4일 발효 시키면 에탄올 농도를 5.57%(w/v), 이론치에 대한 에탄올 수율을 68.86%까지 얻을 수 있었다. Repeated batch culture를 실시한 결과 bead의 활성이 22일 동안 저하되지 않고 유지되었다.

• Journal of Microbiology and Biotechnology
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• 제24권5호
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• pp.629-638
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• 2014

This study describes an alternative mixed culture fermentation technology to anaerobically convert lignocellulosic biomass into butyric acid, a valuable product with wide application, without supplementary cellulolytic enzymes. Rice straw was soaked in 1% NaOH solution to increase digestibility. Among the tested pretreatment conditions, soaking rice straw at $50^{\circ}C$ for 72 h removed ~66% of the lignin, but retained ~84% of the cellulose and ~71% of the hemicellulose. By using an undefined cellulose-degrading butyrate-producing microbial community as butyric acid producer in batch fermentation, about 6 g/l of butyric acid was produced from the pretreated rice straw, which accounted for ~76% of the total volatile fatty acids. In the repeated-batch operation, the butyric acid production declined batch by batch, which was most possibly caused by the shift of microbial community structure monitored by denaturing gradient gel electrophoresis. In this study, batch operation was observed to be more suitable for butyric acid production.