• Journal of Hydrogen and New Energy
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• v.23 no.4
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• pp.397-403
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• 2012

Galactose, an isomer of glucose with an opposite hydroxyl group at the 4-carbon, is a major fermentable sugar in various promising feedstock for hydrogen production including red algal biomass. In this study, hydrogen production characteristics of galactose-glucose mixture were investigated using batch fermentation experiments with heat-treated digester sludge as inoclua. Galactose showed a hydogen yield compatible with glucose. However, more complicated metabolic steps for galactose utilization caused a slower hydrogen production rate. The existence of glucose aggravated the hydrogen production rate, which would result from the regulation of galactose-utilizing enzymes by glucose. Hydrogen produciton rate at galactose to glucose ratio of 8:2 or 6:4 was 67% of the production rate for galactose and 33% for glucose, which could need approximately 1.5 and 3 times longer hydraulic retention time than galacgtose only condition and glucose only condition, respectively, in continuous fermentation. Hydrogen production rate, Hydrogen yield, and organic acid production at galactose to glucose ratio of 8:2 or 6:4 were 0.14 mL H2/mL/hr, 0.78 mol $H_2$/mol sugar, and 11.89 g COD/L, respectively. Galactose-rich biomass could be usable for hydogen fermenation, however, the fermentation time should be allowed enough.

• Microbiology and Biotechnology Letters
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• v.24 no.2
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• pp.149-154
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• 1996

Effect of glucose addition to xylose medium on xylitol production was investigated by using Candida parapsilosis ATCC 21019 mutant. With increasing the ratio of glucose to xylose in total amount of 50 g/l as glucose and/or xylose, xylitol production was decreased but ethanol and glycerol production were increased. Ethanol and glycerol concentration were maxmum in 10 g/l of xylose and 40 g/l of glucose medium as 21.5 g/l and 3.6 g/l, respecti- vely. No xylitol was formed in glucose medium without xylose because xylitol could be not produced from glucose. With increasing the ratio of glucose to xylose, the activity of xylose reductase which converted xylose to xylitol were decreased. The activities of xylitol dehydrogeiiase which converted xylitol to xylulose and then cell materials were found to be constant regardless of the ratio of glucose to xylose. This results indicated that glucose addition to xylose medium on cell growth was not affected. In order to prevent the inhibitory effect of glucose on xylitol production, glucose in a fermentor was fed with low concentration and then ethanol and glycerol was critically decreased and the xylitol yield from xylose of the culture with glucose feeding was recovered the almost same as that with only 50 g/l of xylose. However, the xylitol yield from total sugars (xylose and glucose) was decreased and glucose was not contributed to xylitol production. Therefore, the fermentation at high concentration of xylose without glucose was carried out. A final xylitol concentration of 242 g/l which corresponding 80.7% of xylitol yield was obtained from 300 g/l of xylose for 273 hours.

• Microbiology and Biotechnology Letters
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• v.25 no.5
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• pp.495-500
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• 1997

Xylitol production from xylose and glucose was investigated using Candida tropicalis KFCC-10960. As glucose concentration in xylose medium was increased, ethanol production increased. However, xylitol production was maximum at glucose concentration of 10 g/l. The concentrated cells grown on xylose or glucose were inoculated in xylose medium. The specific activities of xylose reductase and xylitol dehydrogenase, and xylitol production in concentrated cells grown on glucose were the same as those in concentrated cells grown on xylose. The results suggested that cells grown on glucose had the same xylitol producing activity as those grown on xylose. By feeding glucose in xylose medium, cell growth was achieved from glucose and xylitol production was obtained from xylose. By using this technique, a final xylitol concentration of 261 g/l was achieved from 300 g/l xylose in 41 hours which corresponded to a xylitol yield from xylose of 87% and a xylitol productivity of 6.37 g/1-h.

• KSBB Journal
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• v.10 no.3
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• pp.323-334
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• 1995

The effects of glucose on cell growth kinetics, monoclonal antibody productivity, and cell metabolism or hybridoma cells were investigated. The mouse-mouse hybridoma cell line VIII H-8 producing mouse IgG2a was used as a modal system. Glucose showed substrate inhibition type dependence on specific growth raie. The maximum cell density increased as initial glucose concentration increased up to 4 g/$\ell$. Glucose showed a strong influence on cell death kinetics, and an inverse relationship between specific death rate and glucose concentration was found. Cell viability and monoclonal antibody production increased as initial glucose concentration increased. The specific glucose consumption rate increased with glucose concentration, and cumulative specific lactate production rate increased with increasing initial glucose concentration. The overall kinetics of ammonium ion production was almost invariant with respect to initial glucose concentration, while the cumulative specific ammonium ion production rate was dependent on initial glucose concentration.

• Microbiology and Biotechnology Letters
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• v.24 no.4
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• pp.404-407
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• 1996

The effects of carbon sources on vancomycin production were investigated using Nocardia orientalis CSVC 3300. Among carbon sources tested, glucose, maltose and fructose were effective for the production of vancomycin. Glucose was favored for growth, but decrease the production of vancomycin at the concentration above 7.5%. In comparison, maltose did not decrease the production of vancomycin up to the concentration of 20%. When the mixture of glucose and maltose was used in the ratio 1:3 to 1:4, the highest production of vancomycin was achieved. When glucose concentration was set at 3.0%, catabolite repression could not be observed up to total sugar concentration of 16.0%. Fermentation was carried out using commercial hydrolyzed starch composed of glucose, maltose, maltotriose and maltotetraose, The initial glucose concentration was set at 3.0% and subsequent oligosaccharide consumption was monitored by checking their supernatant with HPLC. During initial cultivation for 38 hour, glucose was the sole carbon source leading to rapid growth. After cell growth stopped, the maltose and glucose concentrations increased due to degradation of maltotriose and maltotetraose, but glucose level was maintained at around 3.0%. After 70 hour fermentation, maltose slowly converted to glucose, and vancomycin production continued during the period.

• The Korean Journal of Food And Nutrition
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• v.10 no.1
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• pp.117-121
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• 1997

The glucose isomerase productivity of Arthrobacter sp. L-3 was studied. glucose plus xylose showed higher productivity of glucose isomerase than any other carbon sources. Yeast extract showed higher productivity of glucose isomerase than any other nitrogen sources. The optimum culture time for the production of glucose isomerase was 40hrs.

• Korean Journal of Food Science and Technology
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• v.28 no.6
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• pp.1151-1156
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• 1996

Effects of xylose and glucose on the xylitol production were investigated with Candida parapsilosis KFCC 10875. With increasing the ratio of glucose to xylose, xylitol production decreased but ethanol and glycerol production increased. The maximum concentrations of ethanol and glycerol were 21.5 g/l and 3.6 g/l, respectively, in a medium consisting of 10 g/l xylose and 40 g/l glucose. No xylitol was formed in the glucose medium without xylose since xylitol could not be produced from glucose alone. The inhibitory effect of ethanol, a major by-product, on xylitol production was also studied. As the added ethanol concentration was increased, xylitol production decreased. When cells were inoculated in a xylose medium after removing the by-product (ethanol), xylitol production was not inhibited. The concentrated cells grown on xylose or glucose were inoculated in a fermentor containing the xylose medium. The total activities $(specific{\;}activities{\times}\;cell\;concentration)$ of xylose reductase and xylitol dehydrogenase in concentrated cells grown on glucose were the same as those in a normal fermentation; the specific activities of the above enzymes in the cells grown on xylose were the same as those in a normal fermentation. It indicates that the xylitol productivity of concentrated cells grown on xylose could be increased with increasing the cell concentration. By using concentrated cells of 20 g/l grown on xylose, the final xylitol concentration of 40 g/l was obtained for 18 h fermentation from 50 g/l xylose.

• Biotechnology and Bioprocess Engineering:BBE
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• v.7 no.3
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• pp.171-177
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• 2002

The metabolic flux pattern for L-histidine production was analyzed when glucose and/or acetate were used as carbon sources. Total L-histidine production was enhanced when mixed substrate (glucose and acetate) was used, compared wish that when either glucose or acetate was used as the sole carbon source. Theoretical maximum carbon fluxes through the main pathways for L-histldine production, cell growth, and ATP consumption for cell maintenance were obtained by the linear programming (LP) method. By comparison of the theoretical maximum carbon fluxes tilth actual ones, it was found that a large amount of glucose was actually used for maintenance of cell viability. On the other hand, acetate was used for cell growth. After depletion of acetate in the mixed substrate culture, the flux for glucose to L-histldine synthesis was markedly enhanced. A strategy for effective L-histidine production using both carbon sources was proposed.

• Applied Chemistry for Engineering
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• v.18 no.2
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• pp.162-167
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• 2007

Hydrogen production and its dynamics were investigated in the continuous anaerobic digestion process using Clostridium beijerinckii Donker 1926. In this work, glucose was used as a substrate and hydraulic retention times (HRT) were 0.5, 0.25 or 0.125 day. The removal efficiency of carbohydrate was over 99% under all of HRT conditions. As HRT was shorter, COD removal efficiency became lower while hydrogen content in the total gas and hydrogen production rate became higher. The cell growth yield and hydrogen production yield were 0.27 g-VSS/g-glucose and 0.26 L/g-glucose, respectively, at the steady state. It is expected that the microorganism is able to produce hydrogen when used in the wastewater treatment containing carbohydrate such as glucose. Also, the results in this study could be applied to the actual hydrogen gas production, a promising alternative energy.

• Journal of the East Asian Society of Dietary Life
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• v.7 no.1
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• pp.29-33
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• 1997

The efficient production of glucose isomerase (G. I0.) produced form Arthrobacter sp. L-3 was studied. The optimum culture time of the enzyme was 40hr. The maximum enzyme activity was found at glucose concentration 1%. G. I. activity did not affect inoculum size. The glucose isomerase activity was strongly influenced by the addition of glucose.