• Microbiology and Biotechnology Letters
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• v.32 no.3
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• pp.243-248
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• 2004

Production of (R)-3-hydroxybutyric acid (R3HB) by fed-batch culture and continuous culture of metabolically engineered Escherichia coli harboring Ralstonia eutropha PHB biosynthesis and depolymerase genes was examined in a 30 1 pilot-scale fermentor. A new stable two-plasmid system, pBRRed containing the R. eutropha PHB depolymerase gene and pMCS 105 containing the R. eutropha PHB biosynthesis genes, was developed. Among a variety of E. coli strains harboring plasmids, recombinant E. coli XL-10 Gold (pBRRed, pMCS105) was able to produce R3HB with the highest efficiency in a batch culture. By the fed-batch culture of recombinant E. coli XL-10 Gold(pBRRed, pMCS 105) in a 30 1 fer-mentor, the final R3HB concentration was 22.4 g/l giving a productivity of 0.97 g/l-h. To produce R3HB to a high concentration with high productivity, a new strategy of fed-batch culture followed by a continuous culture was investigated. The maximum productivity and R3HB concentration were 5.06 g/l-h and 25.3 g/l, respectively. These results show that economical production of R3HB is possible by recombinant E. coli in large scale.

• Biotechnology and Bioprocess Engineering:BBE
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• v.7 no.4
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• pp.234-236
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• 2002

A process for the production of mannitol from fructose (5% to 25%) using Leuconostoc mesenteroides NRRL B-1149 was investigated. Fermentations were carried out In batch or fed-batch fermentations without aeration at 28$\^{C}$, pH 5.0. When 5% fructose was used In batch culture fermentation, the yield of mannitol was 78% of that expected theoretically. When the frurtose concentration was Increased to 10%, the yield dropped to 59.6% of the theoretical value. However, In the fed-batch culture, using 10% fructose, the yield was 81.9% of the theoretical value. In a 15% fruttose fed-batch culture, with 5% fructose being added initially and the other 10% fructose being added as a continuous supply the final yield was 83.7% of the theoretical yield. When 20% fructose was used In the same manner, the yield was 89.5% of theoretical yield.

• KSBB Journal
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• v.23 no.3
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• pp.213-218
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• 2008

The present study was to investigate the continuous production of alcohol using immobilized carrier manufactured by polymeric materials. Fermentation runs with a crushed rice, with constituents recovered from batch culture and with ones from continuous culture were thus compared. The performances of immobilized carrier were governed by sandwitched synthetic polymers, the evolution of the continuous culture was steadily governed by the production of alcohol in the lag time of batch culture. The main focus was set on the enhancement of the alcohol production by an newly-developed polymeric forms. This polymeric form led to a drastic increase of the microorganism and the production cost in the continuous reactor was thereby reduced. The sandwitched polymeric-formed carrier, which was resistant to external environments, serves as an interesting alternative to maintain the stability of biological process. These whole results were discussed with the aim to better understand the continuous process implied in the microorganism's build-up during cultivation of fermentation broth.

• Journal of Microbiology and Biotechnology
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• v.17 no.7
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• pp.1221-1225
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• 2007

A ${\beta}$-ionone-resistant mutant strain isolated from the red yeast Xanthophyllomyces dendrorhous KCTC 7704 was used for batch and continuous fermentation kinetic studies with glucose media in a 2.5-1 jar fermentor at $22^{\circ}C$ and pH 4.5. The kinetic pattern of growth and carotenoid concentration in the batch fermentations exhibited a so-called mixed-growth-associated product formation, possibly due to the fact that the content of intracellular carotenoids depends on the degree of physical maturation toward adulthood. To determine the maximum specific growth rate constant (${\mu}_m$) and Monod constant ($K_s$) for the mutant, glucose-limited continuous culture studies were performed at different dilution rates within a range of $0.02-0.10\;h^{-1}$. A reciprocal plot of the steady-state data (viz., reciprocal of glucose concentration versus residence time) obtained from continuous culture experiments was used to estimate a ${\mu}_m$ of $0.15\;h^{-1}$ and $k_s$ of 1.19 g/l. The carotenoid content related to the residence time appeared to assume a typical form of saturation kinetics. The maximum carotenoid content ($X_m$) for the mutant was estimated to be $1.04\;{\mu}g/mg$ dry cell weight, and the Lee constant ($k_m$), which was tentatively defined in this work, was found to be 3.0 h.

• Microbiology and Biotechnology Letters
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• v.17 no.5
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• pp.504-509
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• 1989

Fermentation condition of Streptococcus lactis IFO 12007 for nisin production was examined. The optimal glucose concentration was 60g/ι. The pH and temperature optimum were 6.5 and 31$^{\circ}C$, respectively. The maximum nisin activity in batch culture was 2000IU/$m\ell$. The fermentation quotients after 7 hours of fermentation in batch culture were; specific glucose uptake rate:0.59g/g/h , specific nisin productivity: 34924IU/g/h, product yield: 5944IU/g, growth yield:0.24, biomass:4.81g/ι. The specific growth rate was affected by pH and temperature and the activation energy for growth was 1.35kcal/mole. pH control was essential for nisin production. Fed-batch culture using 20g/$\ell$ glucose medium produced 1420IU/$m\ell$ after 14 hours. The continuous culture could be operated at below 0.38h$^{-1}$ for nisin production. The steady state nisin concentration and specific nisin productivity were 740IU/$m\ell$ and 45000IU/g/h. The growth yield and maintenance energy were 0.144 and 207mg glucose/g-cell/h.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.301-304
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• 2000

Fed-batch culture was designed to increase cell concentration and astaxanthin content by mutant AJ-6 of Phaffia rhodozyma. Fed-batch culture was performed in the continuous feeding with manual adjustment of flow rate to control glucose concentration. When the final glucose concentration was 100 g/L, the cell and astaxanthin were 38.3 g/L, 34.8 mg/L, respectively. Addition of ethanol(10 g/L), when glucose was depleted, the cell and astaxanthin concentration were 37.2 g/L and 45.6, respectively, 5 g/L of acetic acid supplied, 40.6 g/L, 43.9 mg/L were obtained. Ethanol and acetic acid enhanced the astaxanthin content act as precursor of carotenoid synthesis.

• Korean Journal of Microbiology
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• v.15 no.2
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• pp.63-76
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• 1977

Irradiation with high doses of gamma rays induced the reduction of mycelial weight and anaylase activity, and increased relative amylase activity in surface cultures. Biphase in growth curves was shown in aeration-agitation cultures but the behavior of the first phase of growth could be eliminated by replacing the amylasehydrolysed starch substrates, so that enzyme production was shortened ca. 40 hours and relative amylase activity was increased about 3 times higher before onset of autolysis. In the effect of gibberellin on amylase production, the positive stimulation was appeared to only surface culturs of the liquid medium and the negative effect to shake-cultures in a mutant. Trials of various continuous culture were resulted not only the approalch to the value of amylase activity in surface cultures of liquid medium, but also higher productivity than in batch cultures. The culture-degeneration was observed in two-stage continuous culture, but did not appear in continuous elevation culture.

• Journal of Microbiology and Biotechnology
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• v.2 no.4
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• pp.278-283
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• 1992

Aldehyde production by cells of a methanol utilizing yeast, Hansenula nonfermentans KYP-1 was improved when they were grown in a methanol-limited continuous culture, in comparison with cells grown in a batch culture. A higher cell yield was also obtained in continuous culture than in batch culture. This could be due to the fact that a lower methanol concentration was maintained in the jar fermentor to minimize growth inhibition by methanol. A maximum cell productivity of 0.219 g.$liter^{-1}.hr^{-l}$ and a cell yield of 47% were obtained at dilution rates of 0.1 $hr{-1}$ and 0.06 hr{-1}, respectively. The greatest amount of aldehyde was measured at a dilution rate of 0.08 $hr{-1}$. Under optimum reaction conditions, 915.7 mM of acetaldehyde was produced from 1.5 M ethanol after 21 hours reaction, with a conversion rate of 61%. Propionaldehyde and acrolein were produced with conversion rates of 32.7% and 44%, respectively.

• Journal of Environmental Health Sciences
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• v.20 no.2
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• pp.28-38
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• 1994

New problems have been recently posed on the abnormal foaming (Scum) in an aeration tank and the sludge flotation in a final sedimentation tank during the activated sludge process. However, the activities of the causing bacteria, Nocardia-amarae in an aeration tank have not been searched out at all. Therefore, in this article the activities of Nocardia-amarae in an aeration tank have been closely examined by means of the changes of (F/M) ratio, SRT and inflowing substrate using continuous type and fed-batch type. Summarized results of experiments are as follows. 1. Regrading continuous culture when synthetic wastewater was used substrate neither the increase in the number of Nocardia-amarae in the aeration tank nor the Occurrence of Scum was observed. 2. In the case of fed-batch culture, Nocardia-amarae in the aeration tank increased due to the partial change in substrate and the effect of SRT was significant. 3. Once the scum was formed and the quantity of added Nocardia-amarae and substrate were not changed, the effect of STR was not significant.

• Asian-Australasian Journal of Animal Sciences
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• v.18 no.10
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• pp.1425-1429
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• 2005

Megaspahera elsdenii YJ-4, which was previously isolated as a producer of trans-10, cis-12 CLA, was studied for its carbon source on the CLA production. M. elsdenii YJ-4, was incubated with glucose and lactose, and cultured in batch and continuous culture systems with linoleic acid at various pHs to investigate CLA production. Batch cultures of the ruminal bacterium, M. elsdenii YJ-4, were resistant to stearic acid and linoleic acid, and little growth inhibition was observed even when the fatty acid concentration in the culture was as much as 4 mg $ml^{-1}$. Stationary phase batch cultures (0.25 mg bacterial protein $ml^{-1}$) that had been grown on lactate and incubated with linoleic acid (0.20 mg $ml^{-1}$) produced approximately 12 ${\mu}g$ trans-10, cis-12 CLA mg $protein^{-1}$ and little cis-9, trans-11 CLA was detected. Some linoleic acid was converted to hydrogenated products (chiefly stearic acid), but these fatty acids were less than 5 ${\mu}g$ mg bacterial $protein^{-1}$. Stationary phase batch cultures that had been grown on glucose produced at least 3-fold less trans-10, cis-12 CLA than ones grown on lactate. Cells from lactate-limited continuous cultures produced less trans-10, cis-12 CLA than those from batch culture, but only if the pH was greater than 6.4. When the pH of the lactate-limited continuous cultures was lower than 6.4, trans-10, cis-12 CLA and hydrogenated products declined. Cells from glucose-limited continuous cultures produced less trans-10, cis-12 CLA and hydrogenated products than the cells that had been limited by lactate, but pH had little impact on this production. These results support the idea that M. elsdenii YJ-4 could be one of the major producers of trans-10, cis-12 CLA which causes cows to produce milk with a low fat content.