• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.2
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• pp.181-184
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• 2003

We investigated the effect of ethanol on the production of cellulose and acetic acid fermentation by Gluconacetobacter persimmonensis KJ145. Results showed that bacterial cellulose productivity was highest when 2% ethyl alcohol was added to apple-juice medium. For acetic acid production, 7% ethyl alcohol was needed. Optimal concentration of ethyl alcohol was 5% for simultaneous production of bacterial cellulose and acetic acid. For simultaneous production of bacterial cellulose and acetic acid, optimal nitrogen source and optimal concentration were corn steep liquor and 15% (w/v), respectively Optimal culture time for simultaneous production of bacterial cellulose and acetic acid was 14 days. At the optimal condition, Cluconacetobacter persimmonenis KJ145 produced 7.55 g/L of bacterial cellulose (dry weight).

• Applied Chemistry for Engineering
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• v.21 no.2
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• pp.154-161
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• 2010

In the study, the effect of acid and salt concentrations during the production of bio-ethanol from various brwon-algae raw materials was investigated. Especially, the possibility of the conversion of various polysaccarides contained in Laminaria japonica was studied. Bio-ethanol was produced by Saccharomyces cerevisiae KCCM1129 strains in Laminaria japonica. The maximum bio-ethanol production of 2.09 g/L using heat-treatment of Laminaria japonica was achieved. The optimum concentration for reducing sugar conversion by Laminaria japonica was found to be 3.95 g/L at the HCl concentration of 0.1 N. But bio-ethanol production was higher than the case without the non-acid pretreatment. Among the various polysaccharides, only mannitol produced maximum 3.09 g/L bio-ethanol. In case of laminaran, the ethanol was produced only at 0.15 g/L only in 0.1 N HCl pretreatment medium and cell growth was higher than other pretreatment.

• Microbiology and Biotechnology Letters
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• v.15 no.6
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• pp.430-435
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• 1987

A chitin-immobilized enzyme amyloglucosidase(AMG) and a bacterium Zymomonas mobilis were coentrapped in alginate gel beads. Ethanol production was performed in a packed bed column reactor in a simultaneous saccharification and fermentation(SSF) mode using liquefied sago starch as a substrate. It was found that this process eliminated product inhibition and reverse reaction of glucose enhancing the rate of saccharification and ethanol production. At a low dilution rate of D = 0.11 hr$^{-1}$, the steady-state ethanol concentration was 46.0g/$m\ell$ (96.8 % of theoretical yield). The maximum ethanol productivity was 17.7g/$m\ell$, h at D = 0.83 hr$^{-1}$ when the calculation was based on the total working volume. The continuous production of ethanol was maintained stably over 40 days without problems in this reactor system.

• Journal of Microbiology and Biotechnology
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• v.28 no.12
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• pp.1982-1991
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• 2018

Ethanol accumulation inhibited the growth of Saccharomyces cerevisiae during wine fermentation. Autophagy and the release of reactive oxygen species (ROS) were also induced under ethanol stress. However, the relation between autophagy and ethanol stress was still unclear. In this study, expression of the autophagy genes ATG1 and ATG8 and the production of ROS under ethanol treatment in yeast were measured. The results showed that ethanol stress very significantly induced expression of the ATG1 and ATG8 genes and the production of hydrogen peroxide ($H_2O_2$) and superoxide anion (${O_2}^{{\cdot}_-}$). Moreover, the atg1 and atg8 mutants aggregated more $H_2O_2$ and ${O_2}^{{\cdot}_-}$ than the wild-type yeast. In addition, inhibitors of the ROS scavenging enzyme induced expression of the ATG1 and ATG8 genes by increasing the levels of $H_2O_2$ and ${O_2}^{{\cdot}_-}$. In contrast, glutathione (GSH) and N-acetylcystine (NAC) decreased ATG1 and ATG8 expression by reducing $H_2O_2$ and ${O_2}^{{\cdot}_-}$ production. Rapamycin and 3-methyladenine also caused an obvious change in autophagy levels and simultaneously altered the release of $H_2O_2$ and ${O_2}^{{\cdot}_-}$. Finally, inhibitors of the mitochondrial electron transport chain (mtETC) increased the production of $H_2O_2$ and ${O_2}^{{\cdot}_-}$ and also promoted expression levels of the ATG1 and ATG8 genes. In conclusion, ethanol stress induced autophagy which was regulated by $H_2O_2$ and ${O_2}^{{\cdot}_-}$ derived from mtETC, and in turn, the autophagy contributed to the elimination $H_2O_2$ and ${O_2}^{{\cdot}_-}$.

• Journal of Life Science
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• v.22 no.4
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• pp.508-515
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• 2012

In this study, DEAE-cotton [derivatized by 2-(diethylamino)ethyl chloride hydrochloride (DEAE HCl)] was prepared as a carrier for immobilized $Pichia$ $stipitis$ for ethanol production. When cotton was derivatized with 0.5 M DEAE HCl, the yeast cell suspension was adsorbed at 100% of the initial cell $OD_{600}$. The adsorbed yeast cells were estimated to be 101.8 mg-dry cells/g-DEAE-cotton. In particular, when a flask culture using the immobilized yeast cells was conducted in a glucose and xylose-containing medium, the yeast cells on the DEAE-cotton gradually produced ethanol, according to glucose and xylose consumption; the ethanol yield was approximately 0.33 g-ethanol/g-monosaccharide. Because DEAE-cotton was successfully used as a carrier for ethanol production from a glucose and xylose-containing medium, we expect that this bioethanol production process may be used for the bioethanol production process from the hydrolysate of lignocellulosic biomass. All the results of DEAE-cotton were compared with those of DEAE-cellulose as a carrier for immobilization.

• Journal of the Korean Wood Science and Technology
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• v.44 no.3
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• pp.389-397
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• 2016

In this study, ethanol was produced from a biomass hydrolysate that had been treated by electrodialysis (ED) and Amberlite XAD resin to remove fermentation inhibitors. Most of the acetic acid (95.6%) was removed during the ED process. Non-ionizable compounds such as total phenolic compounds, 5-hydroxymethyl furfural, and furfural were effectively removed by the XAD resin treatment. Ethanol production was improved when the ED-treated hydrolysate was treated with XAD-4 resin for a short reaction time. The highest ethanol production from ED-treated hydrolysate was $6.16g/{\ell}$ (after 72 h of fermentation) when the treatment with XAD-4 resin was for 5 min. Among the lignin-derived fermentation inhibitors tested, syringaldehyde in low concentrations (1 and 2 mM) in the hydrolysate increased ethanol production, whereas a high concentration (5 mM) inhibited the ethanol production process. A synthetic medium containing syringaldehyde and ferulic acid was prepared to investigate the synergistic effect of inhibitors on ethanol fermentation. Ethanol production decreased in the mixture of 1 mM syringaldehyde and 1 mM ferulic acid, implying that the effect of ferulic acid on ethanol fermentation is comparable to that of syringaldehyde.

• Journal of the Korean Wood Science and Technology
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• v.41 no.6
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• pp.507-514
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• 2013

In this study, oxalic acid pretreatment of empty fruit bunch (EFB) was performed at different pretreatment temperatures. Also, we evaluated oxalic acid recovery from hydrolysate by electrodialysis. The fermentable sugar concentration in hydrolysate was high at more than $20g/{\ell}$, when pretreatment was carried out at $150^{\circ}C$. At the same time, ethanol production was $3.78g/{\ell}$ after 72 h which correspond to the ethanol yield of 0.21 g/g. On the other hydrolysate (160, $170^{\circ}C$), fermentable sugar was not consumed by Pichia stipitis during fermentation. Most of the oxalic acid was recovered and some of the fermentation inhibitors were removed by electrodialysis. For the electrodialysis treated hydrolysate, ethanol production was increased compared to the original hydrolysate. The highest ethanol production was $5.38g/{\ell}$ after 24 h which correspond to the yield of 0.33 g/g. The ethanol production by simultaneous saccharification and fermentation (SSF) under all pretreatment conditions was more than $15g/{\ell}$ after 96 h. The highest ethanol production was $20.54g/{\ell}$, when pretreatment was performed at $170^{\circ}C$. In particular, ethanol production was increased, when electrodialysis treated hydrolysate was used for SSF.

• Journal of Microbiology and Biotechnology
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• v.8 no.5
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• pp.441-448
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• 1998

A cellobiose-utilizing recombinant yeast having $\beta$-glucosidase activity was developed for ethanol production from a mixture of glucose and cellobiose. Using $\delta$-sequences of Tyl transposon of yeast as target sites for homologous recombination, a heterologous gene of $\beta$-glucosidase was integrated into the chromosome of Saccharomyces cerevisiae. The $\delta$-integrated recombinant yeast, Saccharomyces cerevisiae L2612 (Pb-BGL), showed perfect mitotic stability even in nonselective media and showed ca. 1.5 fold higher $\beta$-glucosidase activity than the recombinant yeast harboring the $2\mu$-based plasmid vector system. A mathematical model was developed to describe the $\beta$-glucosidase formation and ethanol production from the Saccharomyces cerevisiae L2612 ($p\delta-BGL$). The model newly described that the heterologous $\beta$-glucosidase production mediated by ADH1 promoter is regulated by glucose and repressed by ethanol.

• Journal of Microbiology and Biotechnology
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• v.19 no.10
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• pp.1161-1168
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• 2009

Ethanol production by the simultaneous saccharification and fermentation (SSF) of low-value rice wine cake (RWC) without cooking was investigated. RWC is the filtered solid waste of fermented rice wine mash and contains 53% raw starch. For the SSF, the RWC slurry was mixed with the raw-starch-digesting enzyme of Rhizopus sp. and yeast, where the yeast strain was selected from 300 strains and identified as Saccharomyces cerevisiae KV25. The highest efficiency (94%) of ethanol production was achieved when the uncooked RWC slurry contained 23.03% starch. The optimal SSF conditions were determined as 1.125 units of the raw-starch-digesting enzyme per gram of RWC, a fermentation temperature of $30^{\circ}C$, slurry pH of 4.5, 36-h-old seeding culture, initial yeast cell number of $2{\times}10^7$ per ml of slurry, 17 mM of urea as the nitrogen additive, 0.25 mM of $Cu^{2+}$ as the metal ion additive, and a fermentation time of 90 h. Under these optimal conditions, the ethanol production resulting from the SSF of the uncooked RWC slurry was improved to 16.8% (v/v) from 15.1% (v/v) of pre-optimization.

• Journal of Microbiology and Biotechnology
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• v.23 no.9
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• pp.1244-1252
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• 2013

Sugar beet pulp is an abundant industrial waste material that holds a great potential for bioethanol production owing to its high content of cellulose, hemicelluloses, and pectin. Its structural and chemical robustness limits the yield of fermentable sugars obtained by hydrolyzation and represents the main bottleneck for bioethanol production. Physical (ultrasound and thermal) pretreatment methods were tested and combined with enzymatic hydrolysis by cellulase and pectinase to evaluate the most efficient strategy. The optimized hydrolysis process was combined with a fermentation step using a Saccharomyces cerevisiae strain for ethanol production in a single-tank bioreactor. Optimal sugar beet pulp conversion was achieved at a concentration of 60 g/l (39% of dry weight) and a bioreactor stirrer speed of 960 rpm. The maximum ethanol yield was 0.1 g ethanol/g of dry weight (0.25 g ethanol/g total sugar content), the efficiency of ethanol production was 49%, and the productivity of the bioprocess was 0.29 $g/l{\cdot}h$, respectively.