• Journal of Microbiology and Biotechnology
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• v.26 no.3
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• pp.498-502
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• 2016

3'-Hydroxygenistein can be obtained from the biotransformation of genistein by the engineered Pichia pastoris X-33 strain, which harbors a fusion gene composed of CYP57B3 from Aspergillus oryzae and a cytochrome P450 oxidoreductase gene (sCPR) from Saccharomyces cerevisiae. P. pastoris X-33 mutants with higher 3'-hydroxygenistein production were selected using a periodic hydrogen peroxide-shocking strategy. One mutant (P2-D14-5) produced 23.0 mg/l of 3'-hydroxygenistein, representing 1.87-fold more than that produced by the recombinant X-33. When using a 5 L fermenter, the P2-D14-5 mutant produced 20.3 mg/l of 3'-hydroxygenistein, indicating a high potential for industrial-scale 3'-hydroxygenistein production.

• Microbiology and Biotechnology Letters
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• v.19 no.2
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• pp.179-185
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• 1991

We examined optimum culture conditions of Rhodopseudomonas sphaeroides B5 for effective utilization of substrate and sunlight for hydrogen production. The optimum concentration range of DL-lactate as electron donor for hydrogen production by resting cells was from 5 to 50mM, and optimun CN ratio (lactate/glutamat) for maintenence of hydrogen production activity by growing cultures was from 5 to 6. Hydrogen production by the cultures of low cell density (0.36mg/ml dry cells) was saturated with 10 Klux light intensity. Under constant illumination of 50Klux which was set up as the average medium value of annual variation of sunlight intensity, hydrogen production with various cell densities in the culture resulted in highest production rate (132${\mu}$l/hr/mg dry cells) up to 0.64mg/ml dry cells. However, the amount of total hydrogen production was saturated with cell density of 2.1mg/ml dry cells. In addition to these, the optimum inner thickness pervious to light of the culture vessel for hydrogen production which was measured under sunlight was 5 cm.

• KSBB Journal
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• v.23 no.1
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• pp.54-58
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• 2008

Hydrogen is considered as an energy source for the future due to its environmentally friendly use in fuel cells. A promising way is the biological production of hydrogen by fermentation. In this study, the optimization of medium conditions which maximize hydrogen production from Enterobacter aerogenes KCCM 40146 were determined. As a result, the maximum attainable cumulative volume of hydrogen was 431 $m{\ell}$ under the conditions of 0.5M potassium phosphate buffer, pH 6.5 medium containing 30 g/L glucose. The best nitrogen sources were peptone and tryptone for the cell growth as well as hydrogen production. The control of cell growth rate was found to be a important experimental parameter for effective hydrogen production

• Transactions of the Korean hydrogen and new energy society
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• v.12 no.1
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• pp.1-10
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• 2001

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.14 no.1
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• pp.63-68
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• 2009

Among various microscopic organisms producing photobiological hydrogen, cyanobacteria have long been recognized as the promising biological agents for hydrogen economy in 21 century. For photobiological production of hydrogen energy, marine unicellular $N_2$-fixing cyanobacteria have been evaluated as an ideal subgroup of Cyanophyceae. To develope the hydrogen production technology using unicellular $N_2$-fixing cyanobacteria, 3 important factors are pre-requisite: 1) isolation of the best strain from marine natural environment, 2) exploration on the strain-specific optimal conditions for the photobiological hydrogen production, and finally 3) application of the molecular genetic tools to improve the natural ability of the strain to produce hydrogen. Here we reviewed the recent research & development to commercialize photobiological hydrogen production technology, and suggest that intensive R&D during next 10-15 years should be imperative for the future Korean initiatives in the field of the photobiological hydrogen production technology using photosynthetic marine unicellular cyanobacterial strains.

• Microbiology and Biotechnology Letters
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• v.27 no.1
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• pp.46-53
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• 1999

The purpose of this study was to optimize the conditions of continuous mixed culture of C.butyricum and R. spaeroides K-7, which were able to produce hydrogen using biomass-dreived substrate. To investigate the possibility of continuous culture, semi-continuous culture was carried out for 20 days. In semi-continuous culture using the reactor system, the replacement rate of fresh medium was 30% of total medium volume for the highest hydrogen evolution. In continuous culture, the optimum dilution rate was determined to be 0.05$h^{-1}$. The continuous culture produced 3.1 times as compared with the hydrogen on batch culture. On the other hand, the continuous mixed culture produced 1.3~2.1 times as much as hydrogen of the continuous monoculture of C. butyricum. When 10g of glucose in the media (1l) was supplied as a carbon source on continuous culture, mixed culture of C. butyricum and R. sphaeroides K-7 increased hydrogen evolution rate. Because considerable amount of glutamate was contained in waste water of glutamate fermentation, utilization of glutamate was examined in mixed culture. As a result of examination, production of hydorgen was slightly inhibited by high concentration of glutamate, more than 20mM, on continuous monoculture of R. sphaeroides K-7. On the other hand, both on continuous monoculture of C. butyricum and on mixed culture of C. butyricum and R. sphaeroides K-7, production of hydrogen was not inhibited by high concentration of glutamate such as 100mM. Hence this suggests that high concentration of waste water can be used as good substrate for hydrogen production on monoculture of C. butyricum and mixed culture of C. butyricum and R. sphaeroides K-7.

• Journal of Microbiology and Biotechnology
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• v.33 no.5
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• pp.687-697
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• 2023

Identification of novel, electricity-producing bacteria has garnered remarkable interest because of the various applications of electricigens in microbial fuel cell and bioelectrochemical systems. Shewanella marisflavi BBL25, an electricity-generating microorganism, uses various carbon sources and shows broader sugar utilization than the better-known S. oneidensis MR-1. To determine the sugar-utilizing genes and electricity production and transfer system in S. marisflavi BBL25, we performed an in-depth analysis using whole-genome sequencing. We identified various genes associated with carbon source utilization and the electron transfer system, similar to those of S. oneidensis MR-1. In addition, we identified genes related to hydrogen production systems in S. marisflavi BBL25, which were different from those in S. oneidensis MR-1. When we cultured S. marisflavi BBL25 under anaerobic conditions, the strain produced 427.58 ± 5.85 µl of biohydrogen from pyruvate and 877.43 ± 28.53 µl from xylose. As S. oneidensis MR-1 could not utilize glucose well, we introduced the glk gene from S. marisflavi BBL25 into S. oneidensis MR-1, resulting in a 117.35% increase in growth and a 17.64% increase in glucose consumption. The results of S. marisflavi BBL25 genome sequencing aided in the understanding of sugar utilization, electron transfer systems, and hydrogen production systems in other Shewanella species.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.1
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• pp.144-154
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• 2008

The rumen microbial ecosystem produces methane as a result of anaerobic fermentation. Methanogenesis in the rumen is thought to represent a 2-12% loss of energy intake and is estimated to be about 15% of total atmospheric methane emissions. While methanogenesis in the rumen is conducted by methanogens, PCR-based techniques have recently detected many uncultured methanogens which have a broader phylogenetic range than cultured strains isolated from the rumen. Strategies for reduction of methane emissions from the rumen have been proposed. These include 1) control of components in feed, 2) application of feed additives and 3) biological control of rumen fermentation. In any case, although it could be possible that repression of hydrogen-producing reactions leads to abatement of methane production, repression of hydrogen-producing reactions means repression of the activity of rumen fermentation and leads to restrained digestibility of carbohydrates and suppression of microbial growth. Thus, in order to reduce the flow of hydrogen into methane production, hydrogen should be diverted into propionate production via lactate or fumarate.

• Transactions of the Korean hydrogen and new energy society
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• v.28 no.4
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• pp.352-360
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• 2017

Polygeneration process is widely used to pursuit high efficiency by sharing electricity, utility, refrigeration and the utilization of product chemicals. In this paper, performance analysis of the 450 MW Class polygeneration process was conducted with various syngas generated from coal and biomass gasifier. WGSR and PSA process were employed for hydrogen production and separation. Process modeling and dynamic simulation was carried out, and the results were compared with NETL report. Net power of the polygeneration process was 439 MW considering power consumption. More than 90% of CO was converted at WGSR and the hydrogen purity of PSA was more than 99.99%.

• 한국생물공학회:학술대회논문집
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• 2003.04a
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• pp.240-244
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• 2003

A novel integrated method for increasing dissolved oxygen concentration in culture media has been developed. It involves adding hydrogen peroxide to the medium, which is then decomposed to oxygen and water by catalase and adding vegetable oil to the medium as antifoam agent and oxygen vector. A new apparatus for automated addition of hydrogen peroxide to the bioreactor to keep the dissolved oxygen concentration constant over the range $10-100%\;{\pm}\;5%$ was tested. A significant increase (over threefold) of cultivation time was obtained while the dissolved oxygen concentration remained stable ($30%\;{\pm}\;5%$). Therefore, use of corn oil mixed with Ca-stearate as oxygen vector and antifoam and hydrogen peroxide as oxygen source to control excessive foam that was generated by microorganism biosurfactant, GB16-BS produced at Bacillus sp. GB16 cultivation was appropriate for stable cultivation.