• 한국물환경학회지
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• 제28권6호
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• pp.796-803
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• 2012

Potential feasibility of nutrients removal and biofuel production with microalgae was evaluated in batch culture. Distribution of microalgae in fresh water including reservoir and river was investigated to search for the species with high content of lipid that could converted into biofuel. Green algae, Chlorella and Scenedesmus sp., these are known as species containing high lipid content for biodiesel production, were observed in both summer and autumn season. However another highly lipid-containing species, botryococcus sp. was not observed in this study. In mixed culture of microalgae using synthesized wastewater medium, green algae were found to be dominant, comparing to other species of diatoms and blue-green algae. And microalgae were also capable of removing nitrogen and phosphorus in batch experiments. During the culture period of 14 days, removal efficiencies of nitrate and phosphorus were 30% and 82%, respectively. Furthermore, content of the intracellular lipid extracted from algae cell was as favorable as 12-30% in the mixed culture where Scenedesmus and Chlorella sp. were dominant. Therefore the mixed culture of microalgae could be applied to biofuel production and tertiary wastewater treatment, even though there are economic barriers to overcome.

• Journal of Microbiology and Biotechnology
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• 제32권5호
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• pp.663-671
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• 2022

The saccharification of cellulose and hemicellulose is essential for utilizing lignocellulosic biomass as a biofuel. While cellulose is composed of glucose only, hemicelluloses are composed of diverse sugars such as xylose, arabinose, glucose, and galactose. Sulfolobus acidocaldarius is a good potential candidate for biofuel production using hemicellulose as this archaeon simultaneously utilizes various sugars. However, S. acidocaldarius has to be manipulated because the enzyme that breaks down hemicellulose is not present in this species. Here, we engineered S. acidocaldarius to utilize xylan as a carbon source by introducing xylanase and β-xylosidase. Heterologous expression of β-xylosidase enhanced the organism's degradability and utilization of xylooligosaccharides (XOS), but the mutant still failed to grow when xylan was provided as a carbon source. S. acidocaldarius exhibited the ability to degrade xylan into XOS when xylanase was introduced, but no further degradation proceeded after this sole reaction. Following cell growth and enzyme reaction, S. acidocaldarius successfully utilized xylan in the synergy between xylanase and β-xylosidase.

• Journal of Microbiology and Biotechnology
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• 제22권11호
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• pp.1471-1477
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• 2012

Carotenoids produced by non-photosynthetic bacteria protect organisms against lethal photodynamic reactions and scavenge oxygenic radicals. However, the carotenoid produced by Gordonia alkanivorans SKF120101 is coupled to reducing power generation. SKF120101 selectively produces carotenoid under light conditions. The growth yield of SKF120101 cultivated under light conditions was higher than that under dark condition. In the cyclic voltammetry, both upper and lower voltammograms for neutral red (NR) immobilized in intact cells of SKF120101 were not shifted in the condition without external redox sources but were commonly shifted downward by glucose addition and light. Electric current generation in a biofuel cell system (BFCS) catalyzed by harvested cells of SKF120101 was higher under light than dark condition. The ratio of electricity generation to glucose consumption by SKF120101 cultivated in BFCS was higher under light than dark condition. The carotenoid produced by SKF120101 catalyzes production of reducing power from light energy, first evaluated by the electrochemical technique used in this research.

• 한국수소및신에너지학회논문집
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• 제27권5호
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• pp.526-532
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• 2016

In this study, we synthesized a mediator immobilized biocatalyst([FCA/GOx]/PEI/CNT) by surface modification using ferrocene carboxylic acid(FCA), and evaluated its performance as anode catalyst for biofuel cell. Through the application of FCA on glucose oxidase (GOx), the free amine groups on the lysine residue of GOx surface reacted with carboxylic acid of FCA and make amide bond between GOx and FCA. As the result of that, the electron transfer of catalyst was increased up to 1.91 times($0.468mA{\cdot}cm^{-2}$) than the catalyst without surface modification (GOx/PEI/CNT), and high maxium power density of $1.79mA{\cdot}cm^{-2}$ was gained.

• Korean Chemical Engineering Research
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• 제55권2호
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• pp.258-263
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• 2017

본 연구에서는 글루코스 산화효소(glucose oxidase, GOx), 고분자인 폴리에틸렌이민(polyethyleneimine, PEI), 카본나노튜브(carbon nanotube, CNT)와 벤조퀴논(benzoquinone, BQ)을 이용하여 글루코스 바이오연료전지를 위한 바이오 촉매를 합성하였다. 이를 위해, 지지체인 PEI/CNT 복합체에 BQ를 정전기적 인력을 통해 물리적으로 포집한 뒤, GOx를 담지시켜 합성하였다. 이는 기존에 전자 매개체로서 전해질에 풀어서 사용했던 BQ를 전해질이 아닌 촉매 내에 포집하여 촉매를 구성하였다는 개선점이 크며, 그 결과, BQ가 포집되지 않은 촉매 대비, 1.9배 상승한 $34.16{\mu}A/cm^2$의 최대전류밀도를 얻음을 통해 촉매활성이 개선되었음을 증명하였고, 바이오연료전지의 산화극 촉매로 이용 시, BQ가 포집되지 않은 촉매를 이용한 바이오연료전지에 비해 1.2배 상승한 $0.91mW/cm^2$의 최대출력밀도를 얻었다. 이를 통해 바이오연료전지의 산화극을 위한 촉매로서 GOx와 함께 담지된 매개체 BQ를 포함한 촉매 제조 가능성을 확인하였다.

• Journal of Microbiology and Biotechnology
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• 제9권2호
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• pp.127-131
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• 1999

Anaerobically grown cells of an Fe(III)-reducing bacterium, Shewanella putrefaciens IR-l, were electrochemically active with an apparent reduction potential of about 0.15 V against a saturated calomel electrode in the cyclic voltammetry. The bacterium did not grow fermentatively on lactate, but grew in an anode compartment of a three-electrode electrochemical cell using lactate as an electron donor and the electrode as the electron acceptor. This property was shared by a large number of Fe(III)-reducing bacterial isolates. This is the first observation of a direct electrochemical reaction by an intact bacterial cell, which is believed to be possible due to the electron carrier(s) located at the cell surface involved in the reduction of the natural water insoluble electron acceptor, Fe(III).

• Journal of Microbiology and Biotechnology
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• 제15권2호
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• pp.234-238
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• 2005

Glucose oxidase was immobilized on the carboxylated multi-wall carbon nanotubes (MWNT-COOHs) in the presence of a coulping reagent, 1-ethy1-3-(3-dimethylaminopropy1) carbodiimide. Significant amounts of glucose oxidase were also immobilized on MWNT-COOHs without the coupling reagent. Various conditions for the immobilization of glucose oxidase were optimized. Optimal pH for the maximal activity of the immobilized glucose oxidase shifted to 7 from the optimal pH of 6 for the maximal activity of free enzyme due to the carboxy1 groups on the surface of MWNT-COOHs. An electrode of graphite rod with a diameter of 6 mm was fabricated using the immobilized glucose oxidase. The cyclic voltammetry study of the enzyme electrode revealed that the oxidation of glucose and subsequent transfer of electrons from the oxidation of glucose to the electrode were possible by the immobilized glucose oxidase without a mediator, implying that the enzyme electrode can be utilized for the development of biofuel cells.

• 한국기계가공학회지
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• 제19권2호
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• pp.111-118
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• 2020

Recently, bioenergy research using microalgae, one of the most promising biofuel sources, has attracted much attention. Cell disruption, which can be classified as physical or chemical, is essential to extract functional ingredients from microalgae. In this study, we investigated the cell disruption efficiency of Chlorella sp. using low-frequency non-focused ultrasound (LFNFU). This is a continuously physical method that is superior to chemical methods with respect to environmental friendliness and low processing cost. A flat panel photobioreactor was employed to cultivate Chlorella sp. and its growth curve was fitted both with Logistic and Gompertz models. The temporal change in cell reduction by cell disruption using LFNFU was fitted with a Logistic model. The experimental conditions that were investigated were the initial concentration of microalgal cells, relative amplitude of output ultrasound waves, processing volume of microalgal cells, and initial pH value. The optimal conditions for the most efficient cell disruption were determined through the various tests.

• Korean Chemical Engineering Research
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• 제54권5호
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• pp.693-697
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• 2016

본 연구에서는 탄소나노튜브(CNT), 글루코스 산화효소(Glucose oxidase, GOx) 및 다양한 분자량의 가지달린 폴리에틸렌이민(Polyethyleneimine, branched, bPEI)을 물리적으로 결합하여 GOx/PEI/CNT 구조를 제조한 뒤, 가교제인 테레프타랄데하이드(Terephthalaldehyde, TPA)와 알돌축합반응을 통해 TPA/[GOx/bPEI/CNT] 구조의 촉매를 합성하였으며, 각각의 전기화학적 특성 및 장기안정성 등을 평가하였다. GOx/PEI/CNT의 경우, PEI의 분자량의 증가에 따라 유의한 차이를 확인할 수 없었으나, TPA 도입한 TPA/[GOx/bPEI/CNT]는 PEI 분자의 증가에 따라 전자전달 및 장기안정성은 향상되며 글루코스의 물질전달은 감소함을 확인하였다. 또한 효소연료전지 음극 촉매로서의 최적 bPEI 분자량을 확인한 결과, 750 k PEI를 이용한 촉매(TPA/[GOx/bPEI-750k/CNT]에서 최고의 최대전력밀도($0.995mW{\cdot}cm^{-2}$)를 얻을 수 있음을 확인하였다.

• Journal of Microbiology and Biotechnology
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• 제32권3호
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• pp.378-386
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• 2022

Scenedesmus obliquus ABC-009 is a microalgal strain that accumulates large amounts of lutein, particularly when subjected to growth-limiting conditions. Here, the performance of this strain was evaluated for the simultaneous production of lutein and biofuels under three different modes of cultivation - photoautotrophic mode using BG-11 medium with air or 2% CO₂ and heterotrophic mode using YM medium. While it was found that the highest fatty acid methyl ester (FAME) level and lutein content per biomass (%) were achieved in BG-11 medium with CO₂ and air, respectively, heterotrophic cultivation resulted in much higher biomass productivity. While the cell concentrations of the cultures grown under BG-11 and CO₂ were largely similar to those grown in YM medium, the disparity in the biomass yield was largely attributed to the larger cell volume in heterotrophically cultivated cells. Post-cultivation light treatment was found to further enhance the biomass productivity in all three cases and lutein content in heterotrophic conditions. Consequently, the maximum biomass (757.14 ± 20.20 mg/l/d), FAME (92.78 ± 0.08 mg/l/d), and lutein (1.006 ± 0.23 mg/l/d) productivities were obtained under heterotrophic cultivation. Next, large-scale lutein production using microalgae was demonstrated using a 1-ton open raceway pond cultivation system and a low-cost fertilizer (Eco-Sol). The overall biomass yields were similar in both media, while slightly higher lutein content was obtained using the fertilizer owing to the higher nitrogen content.