• 한국식품저장유통학회지
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• 제5권2호
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• pp.186-190
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• 1998

In order to investigate the possible application of immobilized yeast cells in sparkling wine production instead of riddling puns by the traditional method, fermentation characteristics were tested during the sparkling wine fermentation in the bottle using immobilized yeast cells with alginate. The rates of sugar consumption and alcohol production were faster with free cells than those with immobilized cells during the fermentation. The higher concentration of yeast cells and the lower concentration of alginate in the cell immobilization resulted in the faster sugar consumption and alcohol production. It also resulted in the increase of yeast cell concentration released from immobilized beads during the fermentation. However, no differences were shown in the contents of alcohol, residual sugar and CO2 pressure after fermentation. In case concentration of yeast cells released from immobilized beads during bottle fermentation, the higher concentration of alginate had and the lower had.

• 한국식품영양학회지
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• 제2권2호
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• pp.14-20
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• 1989

A strain of Saccharomyces cerevisiae BY-366 was isolated to produce a strong sucrose-hydrolyzing enzyme. After entrapment of yeast cell invertase with alginate, enzymatic properties of immobilized cells were investigated. The results are as follows. 1. The optimum pH of invertase in immobilized cells and non- immobilized cells was 6.0 and 5.0, and pH stability of invertase in immobilized cells and non- immobilized cells was 6.0 and 5.0, respectively. 2 Activation energy of immobilized cells was 4.7 kcal/mol. 3 The immobilized preparation exhibited high resistance to heat and urea Induced denaturation. 4, The bead size less than 2 mm in diameter was desirable. 5. In spite of repeated use, the enzyme activity of immobilized cells was inhibited slightly in batch reaction, and a small column of the immobilized preparation could hydrolyze relatively high concentration of sucrose almost quantitatively to more than 6 days.

• 미생물학회지
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• 제30권5호
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• pp.355-359
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• 1992

Yeast cells of a fusant strain constructed by protoplast fusion of Saccharomyces cerevisiae and Kluyveromyces frugilis were immobilized on calcium alginate beads. The increment of the ethanol tolerance of this strain to 8.0%, when compared with the parent K, fragilis, was confirmed. Based on the results from jar fermentation, a packed-bed reactor of theh immobilized yeast cells was operated. The optimal performance of the immobilized yeast reactor for ethanol production was achieved when supplying 10% lactose (suplemented 1.0% yeast extract) at a temperature of 30.deg.C. The maximal ethanol productivity was obtained as 13.3 g/I/hr at a dilution rate of $0.76 hr^{-1}$.

• Mycobiology
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• 제48권2호
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• pp.122-132
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• 2020

Citric acid is a commercially valuable organic acid widely used in food, pharmaceutical, and beverage industries. In this study, 260 yeast strains were isolated from soil, bread, juices, and fruits wastes and preliminarily screened using bromocresol green agar plates for their ability to produce organic acids. Overall, 251 yeast isolates showed positive results, with yellow halos surrounding the colonies. Citric acid production by 20 promising isolates was evaluated using both free and immobilized cell techniques. Results showed that citric acid production by immobilized cells (30-40 g/L) was greater than that of freely suspended cells (8-19 g/L). Of the 20 isolates, two (KKU-L42 and KKU-L53) were selected for further analysis based on their citric acid production levels. Immobilized KKU-L42 cells had a higher citric acid production rate (62.5%), while immobilized KKU-L53 cells showed an ~52.2% increase in citric acid production compared with free cells. The two isolates were accurately identified by amplification and sequence analysis of the 26S rRNA gene D1/D2 domain, with GenBank-based sequence comparison confirming that isolates KKU-L42 and KKU-L53 were Candida tropicalis and Pichia kluyveri, respectively. Several factors, including fermentation period, pH, temperature, and carbon and nitrogen source, were optimized for enhanced production of citric acid by both isolates. Maximum production was achieved at fermentation period of 5 days at pH 5.0 with glucose as a carbon source by both isolates. The optimum incubation temperature for citric acid production by C. tropicalis was 32 ℃, with NH₄Cl the best nitrogen source, while maximum citric acid by P. kluyveri was observed at 27 ℃ with (NH₄)₂ SO₄ as the nitrogen source. Citric acid production was maintained for about four repeated batches over a period of 20 days. Our results suggest that apple and banana wastes are potential sources of novel yeast strains; C. tropicalis and P. kluyveri which could be used for commercial citric acid production.

• 한국식품영양과학회지
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• 제27권1호
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• pp.24-28
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• 1998

In order to investigate the possibility of using immobilizing yeast cells with the eliminating purpose of the ridding process in sparkling wine production by the traditional method, the changes in chemical components during and after bottle fermentation by immobilizing yeast cells with alginate were tested. The most volatile compounds, excepting some compounds, were not appreciable different in sparkling wines which obtained from various samples compared. After bottle fermentation, sparkling wine fermented with undergoing riddling process, and tested. The results showed that the taste and aroma of the sparkling wine produced with using immobilized cells were very similar to that produced with using free cells.

• Journal of Microbiology and Biotechnology
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• 제22권12호
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• pp.1673-1680
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• 2012

In this study, DEAE-corncobs [delignified corncob grits derivatized with 2-(diethylamino)ethyl chloride hydrochloride ($DEAE{\cdot}HCl$)] were prepared as a carrier to immobilize yeast (Saccharomyces cerevisiae) for ethanol production. The immobilized yeast cell reactor produced ethanol under optimized $DEAE{\cdot}HCl$ derivatization and adsorption conditions between yeast cells and the DEAE-corncobs. When delignified corncob grit (3.0 g) was derivatized with 0.5M $DEAE{\cdot}HCl$, the yeast cell suspension ($OD_{600}$ = 3.0) was adsorbed at >90% of the initial cell $OD_{600}$. This amount of adsorbed yeast cells was estimated to be 5.36 mg-dry cells/g-DEAE corncobs. The $Q_{max}$ (the maximum cell adsorption by the carrier) of the DEAE-corncobs was estimated to be 25.1 (mg/g), based on a Languir model biosorption isotherm experiment. When we conducted a batch culture with medium recycling using the immobilized yeast cells, the yeast cells on DEAE-corncobs produced ethanol gradually, according to glucose consumption, without cells detaching from the DEAE-corncobs. We observed under electron microscopy that the yeast cells grew on the surface and in the holes of the DEAE-corncobs. In a future study, DEAE-corncobs and the immobilized yeast cell reactor system will contribute to bioethanol production from biomass hydrolysates.

• Journal of Microbiology and Biotechnology
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• 제7권1호
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• pp.62-67
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• 1997

To enhance the hyperproductive and low energy-consuming ethanol fermentation rate, the thermotolerant yeast S. cerevisiae RA-74-2 cells were immobilized. An efficient immobilization condition was proved to be $1.5{\%}$ (w/v) alginate solution, neutral pH and 20 h activation of beads. The fermentation characteristics and stability at various temperatures were examined as compared with free S. cerevisiae RA-74-2 cells. The immobilized cells had excellent fermentation rate at the range of pH 3-7 at 30-$42^{\circ}C$ in 15-$20{\%}$ glucose media. When the seed volume was adjusted to 0.12 (v/v) (6ml bead/50 ml medium), $11{\%}$ (w/v) ethanol was produced during the first 34 hand $12.15{\%}$ (w/v) ethanol [$95{\%}$ (w/v) of theoretical yield] during the first 60 h in $25{\%}$ glucose medium. In repetitive fermentation using a 2 litre fermentor, 5.79-$7.27{\%}$ (w/v) ethanol [76-$95{\%}$ (w/v) of theoretical yield] was produced during the 40-55 h in $15{\%}$ glucose media. These data suggested the fact that alginate beads of thermotolerant S. cerevisiae RA-74-2 cells would contribute to economic and hyperproductive ethanol fermentation at high temperature.

• Journal of Microbiology and Biotechnology
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• 제1권2호
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• pp.130-135
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• 1991

The effects of media composition on citric acid fermentation using surface immobilized Saccharomycopsis lipolytica were studied. The use of the standard medium for these organisms resulted in rapid decrease of citric acid production and a transformation of immobilized cell morphologies from a yeast-type to a mycelium-type. When the standard medium was enriched with vitamins, trace minerals, a growth factor and ammonium to form a Vigorous Stationary Phase (VSP) fermentation type medium, relatively stable citric acid production (10 mg/lㆍh) was obtained. Using the VSP type medium, the surface immobilized cells also retained their yeast-type form.

• 한국미생물·생명공학회지
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• 제19권4호
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• pp.398-404
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• 1991

효모를 Na-alginate에 고정화한 후 연속반응기를 이용한 glucose 발효로 에탄올을 생산하였다. 그 결과 고정화 효모의 활성화 시간은 20~25시간이었다. 연속발효에서 고정화효모의 온도안정성은 30~$37^{\circ}C$였으며 pH 안정성은 pH 4.0~pH 8.0, 최적 희석속도는 $0.2h^[-1}$ 이었고 에탄올생산 최적 당농도는 15%였다. 최적조건에서 에탄올수율은 0.23, 생산된 에탄올 농도는 33.90g/l 그리고 에탄올 생산성은 7.12g/$l\cdot h$로 각각 나타났다.

• 한국미생물·생명공학회지
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• 제14권4호
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• pp.285-291
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• 1986

효모Candida lipolytica 세포를 calcium alginate gel로 포괄 고정화시켜서. 유동층 반응기에서 반응을 수행하여 다음과 같은 결과를 얻었다. 1 고정화 효모 세포를 활성화 용액에서 회분식 유동층 반응기 방식과 연속식 유동층 반응기 방식으로 활성화시켰을 때, 세포는 고정화된 상태로 증식하였으며, 또한 세포당 시트르산 생성활성 이 증가하여서, 활성화되지 않은 bead보다 최대 시트르산 생성활성이 약 10배정도 증가되었다. 2 연속식 유동층 반응기 방식으로 활성화시킬 때가 회분식 유동층 반응기 방식으로 활성화시킬 때보다 늦은 시간에 최대의 시트르산 생성활성을 나타내었는데, 이것은 연속식으로 활성화시킬 때는 bead가 계속 새로운 환경에 놓이게 되어 bead내의 세포에 필요한 효소 및 보효소가 bead밖으로 계속 유출됨으로 인하여 bead내의 효소와 보효소의 축적에 많은 시간이 걸린데 기인한 것으로 사료된다. 3. 회분식 유동층 반응기내에서 세포수를 동일하게 하여 반응을 수행할 때, 고정화 bead의 크기가 작을수록 시트르산의 생산성이 증가하였다. 이것은 bead의 크기가 작을수록 부피에 비해 높은 표면적을 가지므로 세포의 많은 수가 반응에 참여하게 되며 bead내로의 화산저항이 작아서 물질전달이 잘되어 시트르산이 많이 생성된 것으로 사료된다.