• Journal of Microbiology and Biotechnology
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• v.15 no.1
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• pp.55-58
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• 2005

Sophorolipid was produced by Candida bombicola ATCC 22214 from soybean dark oil, a byproduct of soybean oil processing. With a fed-batch culture of C. bombicola for 7 days, 90 g/l of sophorolipid was obtained. The CMC (critical micelle concentration) and minimum surface tension of the sophorolipid in aqueous solution were found to be 150 mg/l and 48 mN/m, respectively. The dispersion capability of sophorolipid was higher than that of the chemical surfactants such as SDS and Brij30. The molar solubility ratio (MSR) of 4-methylnaphthalene was 0.2. Linoleic and oleic acids were the main constituents of the fatty acid composition of the sophorolipid. The sophorolipid showed antimicrobial activity against Propionibacterium acne and Bacillus subtilis.

• The Microorganisms and Industry
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• v.19 no.4
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• pp.39-43
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• 1993

최초의 압착 빵효모는 1781년경에 Holland에서 Dutch process로 생산되었으며, 이때에 원료에 대한 4-6%의 압착효모만을 생산하였다. 1846년 비엔나에서 효모발효중에 생성된 거품을 계속하여 수집하여 효모를 회수하는 방법인 Vienna process가 Mautner에 의해 개발되었다. 압착효모 생산 수율은 약 14%로 증가되었고, 알코올은 30%이었다. 1879년 Marquardt가 맥주용 당액에 공기를 공급하면서 발효한 결과를 발표한 후, 빵효모제조에도 공기공급 방법을 사용하게 되었으며, 이것은 압착효모의 생산수율은 50-60%로 높아졌으나, Ethanol의 생산 수율은 20%로 떨어지게 되었다. 그후 1919년 Sak(덴마크)와 Hayduck(독일)은 동시에 incremental-feeding과 fed-batch process의 기초가 된 zulauf 방법을 개발하여 발표하였고, 같은 시기에 1차 세계 대전으로 인한 식량부족은 원료인 곡류를 당밀로 대체하게 되었으며, 이와 같은 제조기술의 계속적인 발달과 원료의 수율은 이론수율에 도달하게 되었고, 수요의 증가로 인하여 양조산업과 분리, 독립되어 빵효모공업이 발전되었다.

• Journal of the Korean Institute of Intelligent Systems
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• v.3 no.3
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• pp.3-18
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• 1993

본 논문에서는 박테리아에서 생성되는 생체 계면활성제인 emulsan의 생산을 위한 유가식 배양에서 에칸을 농도의 제어에 퍼지기법을 적용하였다. 기절저해가 있는 유가식 배양에서 emulsan의 생산을 향상시키기 위해 최대 비성장속도를 갖는 최적 기질농도가 유지되도록 기질인 에탄올의 공급 속도가 조절되어 졌다. 생물반응기에서 Acunetobacter calcoaceticus RAG-1 박테리아를 회분식과 유가식으로 배양 실험하여 최적 에탄올 농도를 구하고, kinetic 모델을 제시하였다. 배양실험의 결과와 지식을 바탕으로 퍼지 규칙을 구성하였다. 퍼지 제어기에서 제어 입력변수는 기질농도의 최적치와 운전치의 오차와 오차의 변화로서 구성되고, 제어 출력변수는 기질 공급 속도의 변화량으로 구성되었다. 멤버쉽 함수를 입력변수의 퍼지 집합화 과정을 통하여 구하였고, 최소-최대법과 무게 중심법을 이용하여 출력 제어값을 구하였다. 유가식 배양의 전산모사와 실험 결과에서 퍼지제어 기법은 최적 기질 농도를 정확히 제어하였으며, emulsan 생산은 향상되었다.

• Microbiology and Biotechnology Letters
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• v.20 no.2
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• pp.207-212
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• 1992

An anti-inflammatory agent, serratiopeptidase, was produced from the culture of the Serratia marcescens. The effects of carbon sources, nitrogen sources and inducers on the production were investigated. Citrate was found to be inhibitory in the production of serratiopeptidase. The enzyme was synthesized in the synthetic medium without inducers, albeit low level of synthesis. But the synthesis was increased by the addition of proteinaceous substrate and leucine. Induction of extracellular proteinase by its end-product was discovered, which is not common in the proteinase synthesis in the bacteria. By the glucose fed-batch culture, we found the possible catabolite repression on the production of serratiopeptidase.

• Journal of Microbiology and Biotechnology
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• v.10 no.5
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• pp.628-631
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• 2000

The timing of poly(3-Hydroxybutyrate) (PHB) biosynthesis was controlled by varying the agitation speed of a stirred tank fermentor during the pH-stat fed-batch culture of recombinant Escherichia coli strain GCSC 6576 harboring pSYL107. Using a concentrated whey solution containing ca. 200 g/l lactose as the nutrient feed, the PHB content was only 57% after 35h due to volumetric limitation of the fermentor. However, by limiting the oxygen by maintaining the agitation speed at 300 rpm, the final PHB content increased to 70% after 70h with a cell concentration of 15 g/l. When the agitation speed was increased up to 500 rpm, a cell concentration of 31 g/l with 80% PHB was obtained after 52h. A further increase in the maximum agitation speed increased the cell concentration, PHB concentration, and PHB productivity, however, the PHB content decreased to 56-58%.

• Proceedings of the KIEE Conference
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• 1999.07g
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• pp.3274-3275
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• 1999

This paper presents a new method of spacer assembly using anodic bonding method which is very simple and clean. The spacer having $100{\mu}m(W){\times}2.1{\mu}m(H)$ was bonded on amorphous silicon film of anode plate. Then, the vertical-type electrode was used for assembling of spacer in high voltage field emission display. In these results, we suggested that the vertical-type electrode provided spacer alignment for high aspect ratio and more simple batch process than conventional method.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.77-80
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• 2000

Various analytical methods such as electron microscopy, quinone analysis, and 16S rDNA sequencing studies were used to investigate the microbial communities and to identify the microorganisms responsible for enhanced biological phosphorus removal (EBPR) in an anaerobic/aerobic sequencing batch reactor (SBR) fed with acetate. Electron photomicrographs showed that oval-shaped microorganisms of about $0.7\;{\sim}\;1\;{\mu}m$ in diameter dominated the microbial sludge. These microorganisms contained polyphosphate granules and glycogen inclusions, which suggests that they are a kind of phosphorus accumulating organism. Quinone and 16S rRNA sequence analyses showed that the members of Proteobacteria beta subclass were the most abundant species, which were affiliated with the Rhodocyclus-likes group. Phylogenetic analysis revealed that the two dominating clones of the beta subclass were most distantly related to Propionivibrio dicarboxylicus DSM 5885 and Rhodocyclus tenuis DSM 109 with about 95% and 96% sequence similarity, respectively. Therefore, it was concluded that the oval-shaped organisms related to the Rhodocyclus-likes group are likely to be responsible for biological phosphorus removal in SBR operation supplied with acetate.

• Microbiology and Biotechnology Letters
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• v.29 no.3
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• pp.176-180
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• 2001

In plant tissues intercellular cementing portion called as middle lamella consists of high proportion of protopectin that is water insoluble form of pectin on their backbone Protopectinase (PPase) a heterogeneous group of enzymes that hydrolyze or dissolve the insoluble protopectin in plant tissues by restricted depolymerization liberates water solu- ble pectin with the resultant separation of plant tissues that have been protected against environmental shock by rigid cel wall . Bacillus subtilis EKll was most effective for PPase Production For increasing of PPase productivity effects of glucose concentrations, pHs and aeration rates were studied in batch culture The most proper concentra- tion of glucose pH and air condition for PPase Production were 1% 8.0 and lvvm respectively In these condi- tion PPase productivity was $84,364 UL^{-1}$ $h^{-1}$ and increased about 15.6 times than flask fermentation.

• Journal of Microbiology and Biotechnology
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• v.17 no.11
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• pp.1898-1903
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• 2007

We attempted to modulate the overall protein expression rate through the addition of a repressor against the araBAD promoter system of Escherichia coli, in which glucose was used as a repressor. Therefore, 0.5% L-arabinose was initially contained as an inducer in culture medium, and either 2% glucose or 2% glycerol was used as a carbon source, and it was found that the expression of recombinant interferon-${\alpha}$ could be observed at the beginning of the batch culture when glycerol was used as a carbon source. However, when glucose was used, the initiation of recombinant interferon-${\alpha}$ expression was delayed compared with that when glycerol was used. Furthermore, when the addition of 0.5% glucose was carried out once or twice after 0.5% L-arabinose induction during DO-stat fed-batch culture, the distributions of soluble and insoluble recombinant interferon-${\alpha}$ were modulated. When glucose was not added after the induction of L-arabinose, all of the expressed recombinant interferon-${\alpha}$ formed an inclusion body during the later half of culturing. However, when glucose was added after induction, the expressed recombinant interferon-${\alpha}$ did not all form an inclusion body, and about half of the total recombinant interferon-${\alpha}$ was expressed in a soluble form. It was deduced that the addition of glucose after the induction of L-arabinose might lower the cAMP level, and thus, CAP (catabolite activator protein) might not be activated. The transcription rate of recombinant interferon-${\alpha}$ in the araBAD promoter system might be delayed by the partial repression. This inhibition of the transcription rate probably resulted in more soluble interferon-${\alpha}$ expression caused by the reduction of the protein synthesis rate.

• KSBB Journal
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• v.10 no.2
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• pp.196-203
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• 1995

The effects of majors nutrients and environmental factors on polyoxins biosysnthesis were examined for the overprodution of antifungal agent polyoxins using Streptomyces sp. 809-11. The cell mass at the exponential growth phase was increased when soluble starch was used, while the polyoxins biosynthesis was increased with the formation of filamentous mycelium when glucose was used as a carbon source. It was, therefore, recommendable to use both soluble starch and glucose simultaneously as carbon sources for the cell growth and polyoxins production. The high concentration of ammonium sulfate (151.4 mM) resulied in the improvement of polyoxins production. The optimal concentration of $K_2HPO_4$for polyoxins production was found to be 0.5mM. By applying fed-batch culture, polyoxins production was improved to about 2-folds compared to the result from the batch culture.