• Journal of Microbiology and Biotechnology
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• v.4 no.1
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• pp.56-62
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• 1994

A yeast strain, BT001, which can directly ferment D-xylose to ethanol was isolated from forest soils, and then identified as Candida sp. Cultural conditions for the optimum ethanol production, along with the effects of aeration on cell growth and ethanol production were investigated. Aeration stimulated the cell growth and the volumetric rate of ethanol production, but decreased the ethanol yield. Optimum temperature and initial pH for the ethanol production were $33{\circ}^C$ and 6.0, respectively. In a shake flask culture, this strain produced 52.3 g ethanol per liter from 12%(w/v) D-xylose after incubation for 96 hours. Ethanol yield was 0.436 g per g D-xylose consumed. This corresponds to 85.8% of theoretical yield. Also, this yeast strain produced ethanol from D-galactose, D-glucose and D-mannose, but not from L-arabinose and L-rhamnose. Among these sugars, D-glucose was the fastest in being converted to ethanol sugars.

• Microbiology and Biotechnology Letters
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• v.25 no.2
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• pp.197-202
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• 1997

Effect of arabinose on xylitol production from xylose by Candida parapsilosis KFCC 10875 was investigated at the different concentrations of arabinose. When the arabinose was added in xylose medium, the cell growth increased and the final cell concentration was maximum at 10 g/l arabinose. The consumption rate of arabinose was greatly lower than those of xylose and arabinose. Above 10 g/l arabinose, it was not completely consumed and then remained in the medium during xylitol fermentation. Estimated cell mass obtained from arabinose increased with increasing consumed arabinose. As arabinose concentration was increased, xylitol production decreased but ethanol production increased. The inhibitory effect of ethanol, a major by-product, on xylitol production was also studied. As the ethanol concentration added increased, xylitol production decreased. When cells were inoculated in a xylose medium after removing ethanol, xylitol production was not inhibited. This results suggested that the inhibition of xylitol production resulted from ethanol which was formed by adding arabinose. It was also interesting that total products(xylitol and ethanol) yield was constant regardless of the arabinose concentration. This result suggested that the total amount of products such as xylitol and ethanol from xylose was constant regardless of the arabinose concentration and arabinose shifted the carbon flow from xylitol to ethanol.

• KSBB Journal
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• v.25 no.2
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• pp.187-192
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• 2010

We designed the optimal operational strategy in repeated fed-batch ethanol fermentation using Sacchromyces cerevisiae ATCC 24858 in views of ethanol yield, specific ethanol production rate, and ethanol productivity, when the aeration rate were controlled at 0.0 and 0.33 vvm. Coincidentally, the time intervals of withdrawal-fill of culture medium (24 and 36 h) were investigated. Ethanol yield and ethanol productivity when the aeration was carried out at 0.33 vvm were superior to those when the aeration was not carried out. Additionally, those parameters when the time interval of withdrawal-fill of culture medium was 24 h were superior to those when time interval of withdrawal-fill of culture medium was 36 h. The total ethanol production reached at the greatest value, 703.8 g-ethanol, when the aeration was carried out at 0.33 vvm and the time interval of withdrawal-fill of culture medium was 24 h. In this study, we verified experimentally the necessity of designing the operational strategy for increasing ethanol production in terms of aeration rate and time interval of withdrawal-fill of culture medium in the repeated fed-batch ethanol fermentation.

• 한국생물공학회:학술대회논문집
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• 2005.10a
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• pp.260-265
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• 2005

In the previous research about ethanol production, we confirmed that SFW(saccharified foodwastes) medium(0.56g-ethanol/g-glucose) is mere efficient than YM medium(0.538g-ethanol/g-glucose). Ethanol production using SFW needs large enzyme cost due to the enzymatic hydrolysis of foodwastes, although the enzymes was obtained from our economical enzyme production methods, using the intact whole culture broth of Trichoderma harzianum FJ1. Therefore, in this research we used synchronous saccharification and fermentationmethod to produce ethanol using foodwastes. Ethanol production yield was 0.45g-ethanol/g-reducing sugar in synchronous saccharification and for-mentation by a fed-batch mode.

• Korean Journal of Microbiology
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• v.23 no.2
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• pp.101-106
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• 1985

The effects of ethanol on the specific rates of growth and ethanol production were found to be threshold and linear inhibition. The degree of inhibition was more apparent on the specific growth rate while ethanol production was continued even the growth was ceased. The nature of uncoupling between the growth (anabolism) and ethanol production (catabolism) was clearly observed under high concentration of ethanol. The uncoupling indicated that ethanol concentration plays a great role in maintenance energy coefficient.

• Journal of Microbiology and Biotechnology
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• v.25 no.3
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• pp.366-374
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• 2015

Herein, we established a repeated-batch process for ethanol production from glycerol by immobilized Pachysolen tannophilus. The aim of this study was to develop a more practical and applicable ethanol production process for biofuel. In particular, using industrial-grade medium ingredients, the microaeration rate was optimized for maximization of the ethanol production, and the relevant metabolic parameters were then analyzed. The microaeration rate of 0.11 vvm, which is far lower than those occurring in a shaking flask culture, was found to be the optimal value for ethanol production from glycerol. In addition, it was found that, among those tested, Celite was a more appropriate carrier for the immobilization of P. tannophilus to induce production of ethanol from glycerol. Finally, through a repeated-batch culture, the ethanol yield (Y_e/g) of 0.126 ± 0.017 g-ethanol/g-glycerol (n = 4) was obtained, and this value was remarkably comparable with a previous report. In the future, it is expected that the results of this study will be applied for the development of a more practical and profitable long-term ethanol production process, thanks to the industrial-grade medium preparation, simple immobilization method, and easy repeated-batch operation.

• Environmental and Resource Economics Review
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• v.27 no.3
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• pp.521-544
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• 2018

This paper investigates the impact of ethanol mandate on the price relationship between corn and beef using the monthly time-series data from January 2003 through December 2013. In addition, we examine the non-linearity in ethanol, corn, and beef markets. Based on the threshold cointegration test, we find the symmetric relationship in pairs with ethanol production-corn price and ethanol production-beef price whereas there is the asymmetric relationship between prices of corn and beef. Employing the threshold vector error correction and vector error correction models, we also find that the corn price in the U.S is caused by both ethanol production and beef price in a long-run when the beef price is relatively high. On the other hand, the corn price does not cause both ethanol production and beef price in the long run. Findings from this study imply that demanders for corn such as ethanol and beef producers have price leadership on corn producers.

• KSBB Journal
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• v.21 no.4
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• pp.267-272
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• 2006

Five strains producing ethanol were isolated from soil near traditional alcohol production factory in Gwangju, Korea. One of the isolated strains maintained relatively stable ethanol production in shaking culture. The isolated strain KJ was proved to be Saccharomyces italicus, based on several biochemical and morphological tests containing assimilation of carbon compounds. In investment of the most suitable carbon for ethanol production, ethanol concentration of 5.46 g/L and yield of 0.53 g-ethanol/g-glucose were obtained in condition of glucose 10 g/L in YM medium. Experimental optimal conditions for ethanol fermentation by S. italicus KJ were as follows; temperature $30^{\circ}C$, initial pH 5.0, initial concentration 10% of glucose, anaerobic condition in the liquid cultivation. When enzymatically saccharified food wastes(SFW) were used as the production medium, ethanol production yield was 0.57 g-ethanol/g-reducing sugar. Therefore, SFW will contribute to lower the production cost of ethanol for industrial application.

• Journal of Microbiology and Biotechnology
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• v.19 no.7
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• pp.666-674
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• 2009

An electrochemical bioreactor (ECB) composed of a cathode compartment and an air anode was used in this study to characterize the ethanol fermentation of Zymomonas mobilis. The cathode and air anode were constructed of modified graphite felt with neutral red (NR) and a modified porous carbon plate with cellulose acetate and porous ceramic membrane, respectively. The air anode operates as a catalyst to generate protons and electrons from water. The growth and ethanol production of Z. mobilis were 50% higher in the ECB than were observed under anoxic nitrogen conditions. Ethanol production by growing cells and the crude enzyme of Z. mobilis were significantly lower under aerobic conditions than under other conditions. The growing cells and crude enzyme of Z. mobilis did not catalyze ethanol production from pyruvate and acetaldehyde. The membrane fraction of crude enzyme catalyzed ethanol production from glucose, but the soluble fraction did not. NADH was oxidized to $NAD^+$in association with $H_2O_2$reduction, via the catalysis of crude enzyme. Our results suggested that NADH/$NAD^+$balance may be a critical factor for ethanol production from glucose in the metabolism of Z. mobilis, and that the metabolic activity of both growing cells and crude enzyme for ethanol fermentation may be induced in the presence of glucose.

• Biotechnology and Bioprocess Engineering:BBE
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• v.10 no.6
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• pp.587-592
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• 2005

Hydrolyzates from lignocellulosic biomass contain a mixture of simple sugars; the predominant ones being glucose, cellobiose and xylose. The fermentation of such mixtures to ethanol or other chemicals requires an understanding of how each of these substrates is utilized. Candida lusitaniae can efficiently produce ethanol from both glucose and cellobiose and is an attractive organism for ethanol production. Experiments were performed to obtain kinetic data for ethanol production from glucose, cellobiose and xylose. Various combinations were tested in order to determine kinetic behavior with multiple carbon sources. Glucose was shown to repress the utilization of cellobiose and xylose. However, cellobiose and xylose were simultaneously utilized after glucose depletion. Maximum volumetric ethanol production rates were 0.56, 0.33, and 0.003 g/L h from glucose, cellobiose and xylose, respectively. A kinetic model based on cAMP mediated catabolite repression was developed. This model adequately described the growth and ethanol production from a mixture of sugars in a batch culture.