• KSBB Journal
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• v.10 no.1
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• pp.55-62
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• 1995

The functional relationship between the initial cell concentration and the ethanol productivity was investigated in the repeated batch fermentation of Sacharomyces cerevisiae ATCC 24858. The repeated batch fermentations were performed in the range of 60 to $150g/\ell$ of initial sugar concentration and 17.5g/$\ell$ to $53.1g/\ell$ of initial cell concentration. The time of one batch fermentation was 1 or 2 hours and the batch fermentation was repeated ten times in every repeated formentaction. The functional relationship showed that the productivity increased non-linearly according to the increase of initial cell concentration regardless of initial sugar concentration. When the initial concentration of sugar was $60g/\ell$ and that of biomass was $34.5g/\ell$, the fermentation was completed within one hour and its ethanol productivity was $26.7g/\ell$.hr, the latter including the times of cell separation, pouring the new substrate into a flask and sampling. When the initial sugar concentration was $120g/\ell$ and the initial cell concentration $50.3g/\ell$, the fermentation was also finished within one hour and its productivity was $45.8g/\ell$$.$hr, The maximum ethanol productivity for eight different repealed fermentations in this work was $53g/\ell$.hr.

• KSBB Journal
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• v.14 no.1
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• pp.24-30
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• 1999

The fed-bach simultaneous saccharification and fermentation (SSF) of newspaper to ethanol with Brettanomyces custersii was studied. The initial substrate concentration for the effective fed-batch SSF was 8% (w/v). The initial optimum enzyme concentration was 30 FPU/g cellulose for cellulase and the optimum volumetric ratio of $\beta$-glucosidase to cellulase was 0.1. When 4% (w/v) of ball-milled newspaper was supplemented intermittently at time intervals, considering the mixing of newspaper slurry, the fed-batch SSF showed higher ethanol concentration (26.80 g/L) and two times higher ethanol production yield based on enzyme than the batch SSF.

• Microbiology and Biotechnology Letters
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• v.32 no.1
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• pp.52-59
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• 2004

When both fructose and galactose were added to a production medium as carbon sources, the productivity of PAFS (Psedomonas Antifungal Substance) biosynthesized by Pseudomonas aeruginosa was observed to be reduced significantly due to the well-known phenomenon of catabolite repression. In order to overcome this phenomenon by use of fermentation bioprocess, fed-batch cultivation method was examined. In addition, a high producer mutant strain, AP-20 obtained by a rational screening method was tested for its productivity of PAFS in both batch and fed-batch fermentation processes. Notably fed-batch operation showed approximately 4 fold higher PAFS productivity than traditional batch operation process. It was appeared that galactose was utilized principally for the cell growth of Pseudomonas aeruginosa whereas large portion of fructose was used for the biosynthesis of PAFS. Furthermore it was observed that composition and feeding rate of production media should be optimized even in the fed-batch fermentation bioprocess. As an example, very slow feeding of carbon sources gave rather negative effect on the production of PAFS due to significant limitation of carbon and energy sources available for the producer microorganism.

• Biotechnology and Bioprocess Engineering:BBE
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• v.9 no.3
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• pp.184-190
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• 2004

The influences of impeller types on morphology and protein expression were investigated in a submerged culture of Aspergillus oryzae. The impeller types strongly affected mycelial morphology and protein production in batch and fed-batch fermentations. Cells that were cultured by propeller agitation grew in the form of a pellet, whereas cells that were cultured by turbine agitation grew in a freely dispersed-hyphal manner and in a clumped form. Pellet-grown cells showed high levels of protein production for both the intracellularly heterologous protein (${\beta}$-glucuronidase) and the extracellularly homologous protein (${\alpha}$-amylase). The feeding mode of the carbon source also influenced the morphological distribution and protein expression in fed-batch fermentation of A. oryzae. Pulsed-feeding mainly showed high protein expression and homogeneous distribution of pellet whereas continuous feeding resulted in less protein expression and heterogeneous distribution with pellet and dispersed-hyphae. The pellet growth with propeller agitation paralleling with the pulsed-feeding of carbon source showed a high level of protein production in the submerged fed-batch fermentation of recombinant A. oryzae.

• Biotechnology and Bioprocess Engineering:BBE
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• v.1 no.1
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• pp.22-25
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• 1996

An Exponetial feeding strategy has been frequently used in fed-batch fermentation of recombinant E. coli. In this feeding scheme, growth yield and initial cell concentration, which can be erroneously determined, are needed to calculate the feed rate for controlling specific growth rate at the set point. The effect of the incorrect growth yield and initial cell concentration on the control of the specific growth rate was theoretically analyzed. Insignificance of the correctness of those parameters for the control of the specific growth rate was shown theoretically and experimentally.

• Microbiology and Biotechnology Letters
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• v.21 no.6
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• pp.615-621
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• 1993

In order to maximize the riboflavin production by a mutant strain Ashbya gosspyii, the optimization of medium and fed-batch fermentation were performed. As carbon sources, glucose and soybean oil were necessary for the riboflavin overproduction. Optimal concentrations of glucose and soybean oil in the flask cultures were found to be 3.0% and 0.5%, respectively, in a complex medium containing corn steep liquor(CLS) 1%. Among the various organic nitrogen sources tested, CSL was the most effective one both for the cell growth and riboflavin overproduction.

• Microbiology and Biotechnology Letters
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• v.21 no.5
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• pp.511-512
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• 1993

The production of vinegar containing high acetic acid concentration was carried in a single stage fed-batch culture. The initial and residual ethanol concentration were 50.0g/l and 5.0g/l, respectively, and the ethanol concentration was maintained from 5.0g/l to 10.0g/l during fedbatch culture. The fermentation temperature was decreased by 1C for every increase of 2.0% in acidity. The maximum productivity was 2.53g/l-hr and the acidity was 16.08% after 40 hours of acetic acid fermentation.

• Biotechnology and Bioprocess Engineering:BBE
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• v.10 no.1
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• pp.23-28
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• 2005

Lactic acid is a green chemical that can be used as a raw material for biodegradable polymer. To produce lactic acid through microbial fermentation, we previously screened a novel lactic acid bacterium. In this work, we optimized lactic acid fermentation using a newly isolated and homofermentative lactic acid bacterium. The optimum medium components were found to be glucose, yeast extract, $(NH_4)_{2}HPO_4,\;and\;MnSO_4$. The optimum pH and temperature for a batch culture of Lactobacillus sp. RKY2 was found to be 6.0 and $36^{\circ}C$, respectively. Under the optimized culture conditions, the maximum lactic acid concentration (153.9 g/L) was obtained from 200 g/L of glucose and 15 g/L of yeast extract, and maximum lactic acid productivity ($6.21\;gL^{-1}h^{-1}$) was obtained from 100 g/L of glucose and 20 g/L of yeast extract. In all cases, the lactic acid yields were found to be above 0.91 g/g. This article provides the optimized conditions for a batch culture of Lactobacillus sp. RKY2, which resulted in highest productivity of lactic acid.

• Journal of Microbiology and Biotechnology
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• v.14 no.4
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• pp.665-672
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• 2004

D-Ribose is a five-carbon sugar used for the commercial synthesis of riboflavin, antiviral agents, and flavor enhancers. Batch fermentations with transketolase-deficient B. subtilis JY1 were carried out to optimize the production of D-ribose from xylose. The best results for the fermentation were obtained with a temperature of $37^{\circ}C$ and an initial pH of 7.0. Among various sugars and sugar alcohols tested, glucose and sucrose were found to be the most effective for both cell growth and D-ribose production. The addition of 15 g/l xylose and 15 g/l glucose improved the fermentation performance, presumably due to the adequate supply of ATP in the xylose metabolism from D-xylulose to D-xylulose-5-phosphate. A batch culture in a 3.7-1 jar fermentor with 14.9 g/l xylose and 13.1 g/l glucose resulted in 10.1 g/l D-ribose concentration with a yield of 0.62 g D-ribose/g sugar consumed, and 0.25 g/l-h of productivity. Furthermore, the sugar utilization profile, indicating the simultaneous consumption of xylose and glucose, and respiratory parameters for the glucose and sucrose media suggested that the transketolase-deficient B. subtilis JY1 lost the glucose-specific enzyme II of the phosphoenolpyruvate transferase system.

• Journal of Microbiology and Biotechnology
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• v.28 no.9
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• pp.1473-1481
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• 2018

A cellulase hyperproducing mutant strain, JNDY-13, was obtained using the ARTP mutation system and with Trichoderma reesei RUT-C30 as the parent strain. Whole-genome sequencing of JNDY-13 confirmed that 105 of the 653 SNPs were point mutations, 336 mutations were deletions and 165 were insertions. Moreover, 99 mutations were insertions and duplications. Among all the mutations, the one that occurred in the galactokinase gene might be related to the production of cellulases in T. reesei JNDY-13. Moreover, the up-regulation of cellulase and hemicellulase genes in JNDY-13 might contribute to higher cellulases production. Under optimal conditions, the highest cellulase activity by batch fermentation reached 4.35 U/ml, and the highest activity of fed-batch fermentation achieved was 5.40 U/ml.