• Journal of Microbiology
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• v.39 no.1
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• pp.79-82
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• 2001

The influence of levulinic acid (LA) on the production of copolyester consisting of 3-hydroxybutyrate (3HB) and 3-hydroxyvalerate (3HV) by Ralstonia eutropha was investigated. Addition of LA into the culture medium greatly increased the molar fraction of 3HV in the copolyester, indicating that LA can be utilized as a precursor of 3HV. In shake flask culture, the 3HV content in the copolyester increased from 7 to 75 mol% by adding 0.5 to 4.0 g/L LA to the medium containing fructose syrup as a main carbon source. A maximal copolyester concentration of 3.6 g/L (69% of dry cell weight) was achieved with a 3HV content of 40 mo1% in a jar fermentor culture containing 4.0 g/L of LA. When LA (total concentration, 4 g/L) was added repeatedly into a fermentor culture to maintain its concentration at a low level, the copolyester content and the 3HV yield from LA reached up to 85% of dry cell weight and 5.0 g/g, respectively, which were significantly higher than those when the same concentration of the LA was supplied al1 at once. The present results indicated that LA is more effective than propionate or valerate as a cosubstrate fur the production of copolyesters with varying molar fractions of 3HV by R. eutropha.

• Journal of Microbiology and Biotechnology
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• v.21 no.1
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• pp.109-114
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• 2011

In this study, we investigated the feasibility of producing bioethanol from the hydrolysate of rape stem. Specifically, the most ideal yeast strain was screened, and the microaeration was performed by surface aeration on a liquid medium surface. Among the yeast strains examined, Pichia stipitis CBS 7126 displayed the best performance in bioethanol production during the surface-aerated fermentor culture. Pichia stipitis CBS 7126 produced maximally 9.56 g/l of bioethanol from the initial total reducing sugars (about 28 g/l). The bioethanol yield was 0.397 (by the DNS method). Furthermore, this controlled surface aeration method holds promise for use in the bioethanol production from the xylose-containing lignocellulosic hydrolysate of biomass.

• Journal of Microbiology and Biotechnology
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• v.4 no.2
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• pp.95-101
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• 1994

The effects of glycine on cell growth and L-omithine production were investigated in shake-flask and jar fermentor cultures of a citrulline auxotrophic mutant, Brevibacterium ketoglutamicum BK 1046. In the shake-flask culture, the optimal concentration of glycine for L-ornithine production was found to be 20 g/l. In the jar fermentor culture with the glycine at an initial concentration of 20 g/l, L-ornithine production increased by 28%, compared to that of the culture with no glycine added. 37 g/l of L-ornithine was produced when additional feeding of glycine (5 g/l) was made. This was a significant improvement in L-ornithine production compared to that (ca. 24 g/l) of the corresponding batch culture conducted without glycine. According to the stoichiometric analysis with the batch fermentation results, the experimental and theoretical L-ornithine yields based on the glucose consumption were 0.24 and 0.59, respectively. This indicates that the performance of L-ornithine fermentation can further be improved by the supplementation of glycine and the development of a mutant strain possessing a higher growth yield.

• Biotechnology and Bioprocess Engineering:BBE
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• v.11 no.4
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• pp.306-312
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• 2006

Two culture modes, continuous and semi-continuous, of the decolorization fungus, Geotrichum candidum Dec 1, were compared to obtain a high treatment efficiency of molasses decolorization and a large productivity of peroxidase (DyP) to simultaneously decolorize dyes and molasses. The continuous culture of G. candidum Dec 1 using a 5-I jar-fermentor showed high DyP activity at a low dilution ratio of $0.005h^{-1}$, and decolorization ratio of molasses of 80% was obtained concomitantly. Therefore, a semi-continuous culture was performed by repeated refill and draw. In this mode, approximately 1.5 liters of the culture broth was replaced per cycle when the decolorization ratio of molasses was near 80%. The molasses medium (1.0 liter per day) was treated and the peroxidase productiveity in the drawn culture broth was 26.6U/day, whereas the peroxidase productiveity was 17.9U/day in the continuous culture with a dilution rate of $0.005h^{-1}$. The semi-continuous treatment system was an efficient decolorization method for the strain, G. candidum Dec 1.

• KSBB Journal
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• v.25 no.3
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• pp.283-288
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• 2010

We investigated the feasibility of bioethanol production from hydrolysate of brown seaweed Sargassum sagamianum. Prior to bioethanol production using yeasts, six yeast strains were compared and the best ones in terms of the ethanol production levels were selected. Pichia stipitis ATCC 7126, Pichia stipitis ATCC 58784, and Pichia stipitis ATCC 58376 were superior to others in terms of ethanol production. These yeast strains were used for producing bioethanol by the shaking bottle culture and the fermentor culture. Out of approximately 30 g/L reducing sugar, about 3~6 g/L and 4~7 g/L bioethanol were produced in the bottle culture and the fermentor one, respectively. Furthermore, it was observed that around 12~28 g-bioethanol was produced from 1 kilogram of Sargassum sagamianum. Compared with those previously published, these data were almost three to eight times higher in value.

• Journal of Microbiology and Biotechnology
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• v.16 no.12
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• pp.1849-1855
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• 2006

It has been shown that the initial conditions of bacterial cultivation are extremely important for the successful production of hyaluronic acid (HA) by fermentation. We investigated several parameters that affect cell growth rate and the productivity and molecular weight of hyaluronic acid--i.e., agitation speed, aeration rate, culture temperature, pH, and pressure--to determine how to optimize the production of HA by Streptococcus zooepidemicus on an industrial scale. Using a 30-1 jar fermentor under laboratory conditions, we achieved maximum HA productivity and biomass when the agitation speed and aeration rate were increased simultaneously. By shifting the temperature downward from 35$^{\circ}C$ to 32$^{\circ}C$ at key levels of cell growth during the fermentation process, we were able to obtain HA with a molecular weight of $2.8{\times}10^6$ at a productivity of 5.3 g/l. Moreover, we reproduced these optimized conditions successfully in three 30-1 jar fermentors. By reproducing these conditions in a 3-$m^3$ fermentor, we were able to produce HA with a molecular weight of $2.9{\times}10^6$ at a productivity of 5.4 g/l under large-scale conditions.

• Microbiology and Biotechnology Letters
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• v.16 no.3
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• pp.205-212
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• 1988

The immobilized cell tubular tormentor was prepared by wood chips or alginate gel. Investigations of characterization of the performance of ethanol fermentation in the immobilized cell tubular tormentor were undertaken and the results were compared with those of other tormentors. The immobilized cell tormentor packed with alginate gel showed much higher ethanol productivity than that with wood chip. It was concluded that the immobilized cell tubular tormentor packed with alginate gel might offer better perspectives for continuous ethanol production than that with wood chip.

• Journal of Microbiology and Biotechnology
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• v.5 no.5
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• pp.285-291
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• 1995

Saccharide utilizations for the growth by Bifidobacterium longum and Bifidobacterium breve were compared. B. longum fermented glucose more rapidly than lactose as a carbon source whereas B. breve fermented lactose at a rate higher than that of glucose. The highest cell concentration, in the case of B. longum, was obtained when cultivated in a jar fermentor that contained modified MRS medium that half the beef extract was replaced by the same amount of tuna extract, and that pH was controlled at 6.0. B. breve showed the best growth when grown in a jar fermentor containing the MRS medium with lactose instead of glucose, controlled at pH 6.0. The optimal concentration of peptone in MRS medium for the growth of B. breve was 5 g/l.

• Microbiology and Biotechnology Letters
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• v.30 no.2
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• pp.167-171
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• 2002

The resting cells of Candida sp. SY16 produced a large amount of mannosylerythritol lipid as a biosurfactant when incubated in the distilled water containing only the carbon source. The resting cells exhibited the highest production at 20 g cells per liter on the soybean oil of 75 g/1 as a sole substrate and pH 4∼5 in the shaking culture. Under the optimal conditions, the biosurfactant was extracellularly produced to 58 g/1 after 120 h in jar fermentor, and the yield became higher than that obtained by using the glowing cells of the strain in batch fermentation.

• Microbiology and Biotechnology Letters
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• v.19 no.4
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• pp.419-427
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• 1991

Ethanol fermentation of glucose by a strain of Saccharomyces cereuisiae was studied in membrane recycle bioreactor, where the fermentation vessel was coupled with cross flow hollow fiber membrane. The cell recycle system controlled backflushing with fresh medium was proven to be effective in alleviating membrane fouling and allowing long term operation of high-cell continuous fermentation. Using 100 g/l initial glucose concentration, the maximum productivity of about 9 5 g/$l \cdot h$ has been achieved at dilution rate 2.5 $h^{-1}$ and bleed stream ratio 0.05 with the corresponding ethanol concentration of 35g/l and glucose conversion of 100%. Increasing the glucose concentration to 200 g/$l \cdot h$ resulted in an increase in ethanol concentration to 48 g/l and productivity to 120 g1l.h. Substrate conversion, however, was only 69%. This productivity was the highest value in the study, and about 38 fold more than that of batch culture and 17 fold more that of single stage continuous culture without cell recycling. No further increase in the productivity was obtained when the glucose concentration was increased reased to 300g/l.