• 한국약용작물학회지
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• 제8권4호
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• pp.351-361
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• 2000

알콜 발효 증진을 위해 5L 배양조에서 혐기적으로 회분 배양 시 건지황 착즙액을 농도별로 첨가하며 알콜 발효 및 균체 생육을 측정한 결과 균체 생육 및 알콜 생산 수율 모두 착즙액 첨가량이 증가함에 따라 일반 발효에 비해 증가했으며, 30% (v/v) 첨가 시 11.8 (g/L)의 최대 균체양, 0.092 (%/hr)의 최대 알콜 생산성과 같은 최대치를 나타냈다. 하지만 40% 이상 첨가 시는 균체 생육 및 알콜 생산 두 경우 다 감소하는 경향을 보였으며 50% 에서는 심각한 생육 저해 현상이 나타났다. 또한 알콜 생산성 증진을 위해 30% 착즙액을 첨가해 유가식 배양을 실시 한 결과 회분 배양보다 월등히 높은 균체 생육 및 알콜 생산성을 보였다. 이 같은 생산성은 일반 알콜 발효에서 얻을 수 있는 수율보다 약 30-40% 이상 높은 것으로 건지황 착즙액이 알콜 발효에 직접적인 영향을 주는 것이 입증되었다. 이는 알콜 발효 시 건지황의 유용 성분의 활용과 함께 알콜 생산 수율 증진에도 이용이 가능한 지황의 이중적 활용도가 있음을 입증한 것으로 평가된다.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 춘계학술발표대회
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• pp.181-184
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• 2000

The cooling rate of a bioreactor was measured to estimate the heat generation by microbial cultivation production. The estimated heat production was calculated from the varying temperature of cooling water. It was used for monitoring growth and specific metabolic events for microbial cultivations. Metabolic heat measured was also adopted for a control parameter for fed-batch cultivation.

• Biotechnology and Bioprocess Engineering:BBE
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• 제7권1호
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• pp.43-51
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• 2002

The cloning and expression of $\beta-glucosidase$ II, encoded by the gene ${\beta}glu2$, from thermotolerant yeast Pichia etchellsii into Escherichia coli is described. Cloning of the 7.3 kb BamHI/SalI yeast insert containing ${\beta}glu2$ in pUC18, which allowed for reverse orientation of the insert, resulted in better enzyme expression. Transformation of this plasmid into E. coli JM109 resulted in accumulation of the enzyme in periplasmic space. At $50^{\circ}C$, the highest hydrolytic activity of 1686 IU/g protein was obtained on sophorose. Batch and fed-batch techniques were employed for enzyme production in a 14 L bioreactor. Exponential feeding rates were determined from mass balance equations and these were employed to control specific growth rate and in turn maximize cell growth and enzyme production. Media optimization coupled with this strategy resulted in increased enzyme units of 1.2 kU/L at a stabilized growth rate of $0.14\;h^{-l}$. Increased enzyme production in bioreactor was accompanied by formation of inclusion bodies.

• 한국균학회지
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• 제35권1호
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• pp.37-42
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• 2007

잣버섯 균사체 배양에 적합한 생물반응기는 풍선형의 공기부양식의 생물반응기가, 수용성 다당체의 생산에도 생장이 좋았던 풍선형 공기부양식 생물반응기가 유리한 것으로 나타났다. 배지의 탄소원 농도별에 따른 수용성 세포외 다당체의 생산량은 농도 처리간 차이가 없었으나 수용성 세포내 다당체는 탄소원 농도가 낮은 즉 C/N율이 낮을수록 증가하였다. 잣버섯 균사체는 고농도의 배지 배양조건에서 생물반응기내로 배지 공급형태가 배지량 증가방법보다 배지농도 조절에 의한 연속 배양방법이 우수한 것으로 나타났다.

• Journal of Microbiology and Biotechnology
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• 제28권10호
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• pp.1706-1715
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• 2018

Several non-methylotrophic bacteria have been reported to improve the growth and activity of methanotrophs; however, their interactions remain to be elucidated. We investigated the interaction between Methylocystis sp. M6 and Microbacterium sp. NM2. A batch co-culture experiment showed that NM2 markedly increased the biomass and methane removal of M6. qPCR analysis revealed that NM2 enhanced both the growth and methane-monooxygenase gene expression of M6. A fed-batch experiment showed that co-culture was more efficient in removing methane than M6 alone (28.4 vs. $18.8{\mu}mol{\cdot}l^{-1}{\cdot}d^{-1}$), although the biomass levels were similar. A starvation experiment for 21 days showed that M6 population remained stable while NM2 population decreased by 66% in co-culture, but the results were opposite in pure cultures, indicating that M6 may cross-feed growth substrates from NM2. These results indicate that M6 apparently had no negative effect on NM2 when M6 actively proliferated with methane. Interestingly, a batch experiment involving a dialysis membrane indicates that physical proximity between NM2 and M6 is required for such biomass and methane removal enhancement. Collectively, the observed interaction is beneficial to the methanotroph but adversely affects the non-methylotroph; moreover, it requires physical proximity, suggesting a tight association between methanotrophs and non-methylotrophs in natural environments.

• Journal of Microbiology and Biotechnology
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• 제5권2호
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• pp.100-104
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• 1995

Production of $poly-{\beta}-hydroxybutyrate$ (PHB) in a strain of Azotobacter chroococcum, a nitrogen-fixing bacteria, was investigated at various levels of nitrogen and oxygen. Feeding nitrogen source increased both cell growth and PHB accumulation. Oxygen supply appeared to be one of the most important operating parameters for PHB production. Both cell growth and PHB accumulation increased with the sufficient supply of air in the fed-batch fermentation of the strain. However, it was also noted that keeping the oxygen level under limited condition was critical to achieve high PHB productivity. A high titer of PHB (52 g/l) with a high cellular content (60%) was obtained after 48 hr of fed-batch operation by controlling the oxygen supply. Dual limitation of nitrogen and oxygen did not further increase the PHB accumulation probably due to the greater demand for reducing power and ATP for nitrogen fixation.

• 한국미생물·생명공학회지
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• 제28권6호
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• pp.341-348
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• 2000

Selection of high producer strain, optimization of production medium and cultivation in bioreactor system were carried out in order to produce an antifungal substance, PAFS in large amounts which sources and 41 kinds of nitrogen sources, a synthetic medium consisting of fructose(70 g/1) and ammonium sulfate (10g/l) and a complex medium including galactose(30g/l), fructose(20g/l) and cottonseed flour(35g/l) were determined as opti-mized media for PAFS production. In bioreactor studies examining physiological characteristics of the pro- ducer microorganism with the complex medium, typical pattern of diauxic growth was observed as demonstrated by the result that fructose was not used before almost exhaustion on readily utilizable carbon source, galactose. When galactose was supplemented additionally during the fermentation period. PAFS pro-ductivity did no increases any more, indicating that large portion of the added galactose was used for cell growth instead of biosynthesis of the secondary metabolite. It was deduced that PAFS production could be enhananced by employing fed-batch operation in order to overcome the apparent phenomenon of catabolite repression and /or inhibition.

• Journal of Microbiology and Biotechnology
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• 제22권3호
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• pp.371-377
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• 2012

The present study describes medium-chain-length polyhydroxyalkanoates (mcl-PHAs) production by the Pseudomonas Gl01 strain isolated from mixed microbial communities utilized for PHAs synthesis. A two-step fed-batch fermentation was conducted with glucose and waste rapeseed oil as the main carbon source for obtaining cell growth and mcl-PHAs accumulation, respectively. The results show that the Pseudomonas Gl01 strain is capable of growing and accumulating mcl-PHAs using a waste oily carbon source. The biomass value reached 3.0 g/l of CDW with 20% of PHAs content within 48 h of cultivation. The polymer was purified from lyophilized cells and analyzed by gas chromatography (GC). The results revealed that the monomeric composition of the obtained polyesters depended on the available substrate. When glucose was used in the growth phase, 3-hydroxyundecanoate and 3-hydroxydodecanoate were found in the polymer composition, whereas in the PHAs-accumulating stage, the Pseudomonas Gl01 strain synthesized mcl-PHAs consisting mainly of 3-hydroxyoctanoate and 3-hydroxydecanoate. The transcriptional analysis using reverse-transcription real-time PCR reaction revealed that the phaC1 gene could be transcribed simultaneously to the phaZ gene.

• Journal of Microbiology and Biotechnology
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• 제8권1호
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• pp.8-13
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• 1998

Animal cells in culture typically convert most of the glucose they consume into lactate. The accumulation of lactate, however, is commonly cited as one of the factors that inhibit cell growth and limit the maximum cell concentration that can be achieved in culture. The specific production of lactate and the amount of glucose converted to lactate can be reduced when cells are grown in a fed-batch culture in which the residual glucose concentration is maintained at low levels. Such a fed-batch culture was used to grow and adapt hybridoma cells into a low-lactate-producing state before changing into continuous culture. The cells reached and maintained a high viable cell concentration at steady state. In a similar manner, cells that were initially grown in batch culture and a glucose-rich environment reached a steady state with a cell concentration that is much lower. The feed composition and dilution rates for both cultures were similar, suggesting steady state multiplicity. From a processing perspective the desired steady state among those is the one with the least metabolite production. At such seady state nutrient concentration in the feed can be further increased to increase cell and product concentrations without causing the metabolite inhibitory effect typically seen in a cell culture. Controlling cell metabolism in a continuous culture to reduce or eliminate waste metabolite production may significantly improve the productivity of mammalian cell culture processes.

• 한국미생물·생명공학회지
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• 제28권5호
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• pp.291-297
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• 2000

A strain producing high levels of compaction was isolated from soil and identified as Penicillium sp. Y-8515 based on the morphological characteristics and ribosomal RNA sequence analysis. Optimization of several different carbon and nitrogen sources for the effective production of compaction was performed resulting in the medium compositions containing 5%(w/v) glucose, 1.0 % soybean meal, 0.5% yeast extract, 0.5%(NH$_4$)$_2$$SO_4$, 0.25%,$ NaH_2$$PO_4$, 0.25% $CaCO_3$. The fixed con-centration of glucose(5%, w/v) and relatively lower concentrations(less than 2.5%, w/v) of soybean meal stimu-lated the transformation of the growth morphology from filamentous to pellet form. Comparing to that by filamentous form, the production of compactin by pellet form increased up to 1.5 folds. In a fed-batch fermentation, continuous feeding of the mixture of glucose and nitrogen source at the ratio of 10:1 showed 3.5-fold more produc-tion yield of compaction comparing to the batch mode.