• KSBB Journal
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• v.5 no.4
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• pp.335-339
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• 1990

In order to develop economic processes for ethanol production from starch, a simultaneous saccharification and fermentation(SSF) process using Zymomonas mobilis and amyloglucosidase (AMG) was studied in semibatch modes using cell recycle. The cell recycle was carried out by adopting two different methods; microfiltration and settling. The cell recycle using microfiltration revealed higher productivity(5.4 g/l/h) than that using a settler(4.3 g/l/h). Taking the large-scale ethanol fermentation into account, the semibatch process using microfiltration system appeared most promising among others with respect to ethanol productivity, feasibility of scale-up and simplification of operation.

• Microbiology and Biotechnology Letters
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• v.26 no.2
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• pp.167-172
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• 1998

In batch cultures of Brevibacterium ketoglutamicum for the L-ornithine production in which the pH and dissolved oxygen concentration were regulated constant, the profiles of redox potential were observed in parallel with the profiles of state variables such as cell, glucose, and ornithine concentrations. It was found that the redox potential had a close relationship with cell concentration and was also affected by ornithine concentration. The effects of ornithine and glucose on redox potential were examined in a separate series of experiments. Based on the experimental results, a correlation of redox potential to glucose, cell and ornithine concentrations has been proposed. The proposed correlation can be used for on-line estimation of ornithine concentration from on-line data of redox potential, glucose concentration, and cell concentration.

• Microbiology and Biotechnology Letters
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• v.26 no.2
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• pp.89-95
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• 1998

Rhodopseudomonas sphaeroides K7 and E15-1 produced hydrogen from glucose rapidly for the first 24 hrs of culture under the anaerobic and photosynthetic conditions and then ceased the hydrogen production because of the accumulation of organic acids such as acetic acid and formic acid in the culture broth, decreasing the pH to 4.2-4.5. Only 43% and 73% of glucose in the culture were consumed even after 6 days of incubation by R. sphaeroides K7 and E15-1, respectively. The hydrogen production and glucose consumption, however, were substantially increased when the pH of the culture was adjusted to 6.8-7.0: Hydrogen production continues even after 10 days of culture and glucose was consumed completely after 2.5 and 4.5 days by R. sphaeroides K7 and E15-1, respectively, Furthermore, the bacteriochlorophyll contents in R. sphaeroides K7 and E15-1 were increased by 44 and 9 folds and the cell concentrations by 10 and 2.5 folds, respectively, after 7 days of culture. R. sphaeroides K7 and E15-1 also produced hydrogen from acetic, lactic, butyric and malic acids under the anaerobic and photosynthetic conditions even though the amounts of hydrogen produced were lower than that from glucose. The results of this experiment indicate that under the anaerobic and synthetic conditions R. sphaeroides K7 and E15-1 might use the NADH oxidation mediated by ferredoxin and hydrogenase to evolve hydrogen from glucose for the first 24 hrs and then the organic acids produced were used as electron donners for the production of hydrogen in the nitrogen-limited condition.

• KSBB Journal
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• v.21 no.2
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• pp.79-84
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• 2006

In order to minimize the reduction of lysine productivity by accumulation of lysine and byproducts in the end of fed-batch fermentations, a salt-tolerant mutant C14-49-3-15-7-3-20, which could grow at high concentrations of NaCl was isolated through mutagenesis from the Corynebacterium glutamicum mother strain I. In the evaluation of L-lysine productivity by fed-batch fermentations using a 5 L jar fermenter, the salt-tolerant mutant strain C14-49-3-15-7-3-20 produced 130.6 g/L of L-lysine with a 48.6% of yield. The mother strain I produced L-lysine concentration only 104.9 g/L with a yield 41.8%, implying the improvement of L-lysine productivity by introduction of salt-tolerance character.

• Korean Journal of Food Science and Technology
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• v.15 no.1
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• pp.51-55
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• 1983

It was investigated under several cultural conditions to produce biomass directly from starch by an strictly aerobic and amylolytic yeast, Sporobolomyces holsaticus FRI Y-5. Its optimal temperature and initial pH of medium for growth were $23^{\circ}C$ and 6.9, respectively. Activation energy, Ea, for growth was calculated to be 17.33 Kcal/mole from the Arrhenius relationship. When each of 13 nitrogen sources was added to the basal medium, $(NH_2)_2CO$ had the best effect, on which concentration of cell after 3 day incubation was 10.6 g/l and cell yield was 0.451. The yeast growth was affected by $MgSO_4,\;K_2SO_4\;and\;ZnSO_4$ as a mineral source and was best on the medium containing all of them. The addition of yeast extract (5g/l) could enhance the production of biomass and cell yield to 77% and 32%, respectively.

• The Korean Journal of Mycology
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• v.15 no.4
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• pp.231-237
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• 1987

A. niger IMI 41873 was shake-cultured in Cassava starch medium, then mycelial dry weight and mycelial protein were measured. The effects of Cassava starch concentrations, various nitrogen sources and concentrations on the levels of mycelial production and mycelial protein were investigated. The results were as follows; In each medium containg 4%, 6%, 8% and 10% of Cassava starch, mycelial production was 13.35 mg/ml, the medium containg 6% of Cassava starch was proved to be most effective. The levels of mycelial protein in shake culture with medium of 6% Cassava starch and $NaNO_3(1.5\;g/l)$ were the highest. Among nitrate, ammonium sulfate, and urea, the nitrate was the most effective on mycelial production.

• KSBB Journal
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• v.11 no.2
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• pp.201-210
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• 1996

The production of polyhydroxyalkanoate(PHA) from glucose by batch and fed-batch culture of Pseudomonas sp. HJ was studied. In batch culture using fermentor, 400 rpm of agitalion speed, 2 vvm of aeration rate, 18 hours of inoculum age, and 5% (vlv) of inoculum size were optimal. PHA production was not increased by deficiency of oxygen. In a batch culture, the final call mass was $6.251g/\ell$, and PHA content was 20% of dry cell weight. In a constant feeding fed-batch culture, cell mass increased to $33.24g/\ell$, and PHA content reached 48.9% of dry cell weight. In an intermittent feeding fed-batch culture, cell mass increased to $37.89g/\ell$, and PHA content reached 53.5% of dty cell weight.

• Korean Journal of Food Science and Technology
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• v.20 no.5
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• pp.724-731
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• 1988

For a study on the production of ${\gamma}-linolenic$ acid(GLA) by microorganisms, fifteen strains of Mucorales obtained from culture stocks and ten isolate strains were compared in their cell growth, lipid content, fatty acid composition and pellet size formed in shake flask culture. Among the fungi examined, the isolated fungus, designated as FB-354, was found to be the most suitable one for the production of GLA mainly due to its high contents of lipid, 29.9% of dry cell weight and GLA, 16.8% of the total fatty acids. The strain FB-354 was tentatively identified as Mucor sp. on the basis of morphological characteristics. Fungal oil produced by Mucor sp. FB-354 was fractionated into 81.1% of neutral lipid, 7.2% of glycolipid, and 11.8% of phospholipid. Although the GLA content in the phospholipid fraction was as high as 21.4%, most of the GLA was found in the neutral lipid fraction.

• Korean Journal of Agricultural Science
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• v.3 no.2
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• pp.244-250
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• 1976

Candida brumptii was one of the best isolates which could grow on alcohol distillation slops (reported in the previous paper). Attempts were made to investigate the cultural conditions for cell mass production by this strain, and the results obtained were as follow. The supernatant of the alcohol distillation slops without dilution support ed better growth of the strain than diluted ones. The addition of ammonium sulfate (0.2%), ammonium phosphate (0.1-0.2%), potassium phosphate (0.2%) to the supernatant resulted in positive effects for the growth, among the various inorganic nitrogen and other salts supplements. BOD and COD of the supernatant were reduced approximately 30% and 20%, respectively in 3 days culture. Cell production was maximized when grown at $35^{\circ}C$ and pH 5.0. The yield of cell mass was 1.03% by dry weight and its crude protein content was about 52.65%

• Korean Journal of Food Science and Technology
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• v.28 no.4
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• pp.756-761
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• 1996

Influence of acetic acid on xylitol production from xylose using Candida parapsilosis KFCC 10875 was investigated at the different concentrations of acetic acid. Acetic acid was totally consumed below 1.0 g/l of its concentration, whereas partially consumed above 3.0 g/l and remained in the medium during xylitol fermentation. Cell growth, xylose consumption, and xylitol production decreased when acetic acid concentration was increased. Specific growth rate of cell and specific consumption rate of xylose also decreased with increasing the concentration of acetic acid. However, the xylitol yield from xylose and specific production rate of xylitol were maximum at 1.0 g/l of acetic acid. The inhibitory effect of acetic acid on xylitol fermentation increased when pH was decreased.