• Journal of Microbiology and Biotechnology
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• 제20권7호
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• pp.1092-1100
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• 2010

Bacteria, fungi, and protozoa inhabiting the rumen, the largest chamber of the ruminants' stomach, release large quantities of hydrogen during the fermentation of carbohydrates. The hydrogen is used by coexisting methanogens to produce methane in energy-yielding processes. This work shows, for the first time, a fundamental possibility of using a hydrogen-rich fermentation gas produced by selected rumen ciliates to feed a low-temperature hydrogen fuel cell. A biohydrogen fuel cell (BHFC) was constructed consisting of (i) a bioreactor, in which a hydrogen-rich gas was produced from glucose by rumen ciliates, mainly of the Isotrichidae family, deprived of intra- and extracellular bacteria, methanogens, and fungi; and (ii) a chemical fuel cell of the polymer-electrolyte type (PEFC). The fuel cell was used as a tester of the technical applicability of the fermentation gas produced by the rumen ciliates for power generation. The average estimated hydrogen yield was ca. 1.15 mol $H_2$ per mole of fermented glucose. The BHFC performance was equal to the performance of the PEFC running on pure hydrogen. No fuel cell poisoning effects were detected. A maximum power density of $1.66\;kW/m^2$ (PEFC geometric area) was obtained at room temperature. The maximum volumetric power density was $128\;W/m^3$ but the coulombic efficiency was only ca. 3.8%. The configuration of the bioreactor limited the continuous operation time of this BHFC to ca. 14 h.

• KSBB Journal
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• 제27권2호
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• pp.97-102
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• 2012

In the present study, the biomass productivity of two green microalgae (Chlorella sp. and Dunaliella salina DCCBC2) were assessed in a 12 L tubular photobioreactor under optimum culture conditions. In the batch culture optimization process, the Chlorella sp. biomass was obtained as 1.2 g/L under atmospheric air as a sole $CO_2$ source and other culture conditions as follows: light intensity, temperature, pH, $NH_4Cl$ and $K_2HPO_4$ were 100 ${\mu}E/m^2/s$, $27^{\circ}C$, 7.0, 20.0 mM and 2.0 mM, respectively. On the other hand, 2.9 g/L of D. salina DCCBC2 biomass production was observed under the following conditions: light intensity, temperature, pH, $KNO_3$ and $K_2HPO_4$were 80 ${\mu}E/m^2/s$, $27^{\circ}C$, 8.0, 3.0 mM and 0.025 mM, respectively. At 1% $CO_2$ supply to the reactor, the Chlorella sp. production was reached 1.53 g/L with 25% increment under the same operating conditions. In addition, the maximum D. salina DCCBC2 biomass was observed as 3.40 g/L at 3% $CO_2$ concentration. Based on the aforementioned optimized conditions, the dilution rate and maximal biomass productivity of Chlorella sp. and D. salina DCCBC2 in the continuous cultivation were 0.4/d and 0.6 g/L/d and 0.6/d and 1.5 g/L/d, respectively.

• KSBB Journal
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• 제23권6호
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• pp.525-528
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• 2008

고농도 산소수를 이용한 새싹 침지로 인한 발아율 및 성장률을 비교하기 위하여 특정 용존산소량의 산소수를 고압 반응기에서 산소를 통한 가압을 통해 생성하였고, 용존산소량을 20, 30, 40, 50 ppm으로 조절한 산소수로 온도 $20^{\circ}C$에서 새싹을 4시간 동안 침지한 후 새싹을 관찰하였다. 그 결과 새싹의 10일째 최종적인 발아율은 일반 증류수 침지 시에 비해 50 ppm 산소수 침지시 최종발아율은 $24.6{\sim}28.6%$ 높게 나타났고, 최종 성장 길이도 $6{\sim}7\;mm$ 정도 높은 값을 나타내어, 새싹의 성장에서 씨앗의 충분한 산소 공급에 의한 발아가 안정적이고 효율적인 성장을 유도함을 알 수 있었다.

• KSBB Journal
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• 제23권6호
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• pp.551-553
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• 2008

본 연구에서는 다양한 침지조건에서의 브로콜리 최적 발아조건을 찾기 위한 실험을 수행하였다. 그 결과 4시간동안 $20{\sim}30^{\circ}C$에서 10 ppm 이상의 용존산소를 공급하면서 침지하였을 경우 약 98.5%의 발아율을 보였다. 산소수의 영향을 관찰한 결과 7, 12 ppm에서 각각 76%, 92%의 발아율을 보였으며, 12 ppm 산소수 공급조건에서 7 ppm에 비해 2배 이상의 생장률을 확인할 수 있었다. 결과적으로 브로콜리의 발아율은 재배 시 산소수의 공급보다 침지 시 산소수를 공급할 경우 증가하는 것으로 판단된다.

• Korean Chemical Engineering Research
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• 제61권2호
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• pp.278-286
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• 2023

The present work evaluated the production of biohydrogen under mesophilic and thermophilic conditions through dark fermentation of palm oil mill effluent (POME) in batch mode using the design of experiment methodology. Response surface methodology (RSM) was applied to investigate the influence of the two significant parameters, POME concentration as substrate (5, 12.5, and 20 g/l), and volumetric substrate to inoculum ratio (1:1, 1:1.5, and 1:2, v/v.%), with inoculum concentration of 14.3 g VSS/l. All the experiments were analyzed at 37 ℃ and 55 ℃ at an incubation time of 24 h. The highest chemical oxygen demand (COD) removal, hydrogen content (H₂%), and hydrogen yield (HY) at a substrate concentration of 12.5 g COD/l and S:I ratio of 1:1.5 in mesophilic and thermophilic conditions were obtained (27.3, 24.2%), (57.92, 66.24%), and (6.43, 12.27 ml H₂/g COD_rem), respectively. The results show that thermophilic temperature in terms of COD removal was more effective for higher COD concentrations than for lower concentrations. Optimum parameters projected by RSM with S:I ratio of 1:1.6 and POME concentration of 14.3 g COD/l showed higher results in both temperatures. It is recognized how RSM and optimization processes can predict and affect the process performance under different operational conditions.

• Journal of Microbiology and Biotechnology
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• 제33권5호
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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.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2003년도 생물공학의 동향(XIII)
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• pp.176-176
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• 2003

• 대한환경공학회지
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• 제30권9호
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• pp.851-861
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• 2008

• 한국미생물학회:학술대회논문집
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• 한국미생물학회 2008년도 International Meeting of the Microbiological Society of Korea
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• pp.80-81
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• 2008

• 한국환경과학회지
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• 제20권2호
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• pp.215-222
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• 2011

The adsorption behavior of nitrate nitrogen was investigated from aqueous solution using char prepared from oak chip. The removal rate of nitrate nitrogen was found to be dependent on temperature and it is increased as the temperature increase. Adsorption equilibrium data of nitrate nitrogen on oak char. reasonably fitted Langmuir and Freundlich isotherm models. The adsorption energy obtained from D-R model was 12.5 kJ/mole at $20^{\circ}C$ indicating an ion exchange process as primary adsorption mechanism. Thermodynamic parameters such as ${\Delta}G^o$, ${\Delta}H^o$, and ${\Delta}S^o$ were -23.76 kJ/mole, 26.1 kJ/mole and 89.7 J/K mole at $20^{\circ}C$, respectively, indicated that the nature of nitrate nitrogen adsorption is spontaneous and endothermic.