• Bulletin of the Korean Chemical Society
• /
• 제30권2호
• /
• pp.302-308
• /
• 2009

This study investigated the production of hydrogen over Ga (1.0, 2.0, and 5.0 mol%)-$TiO_2$ photocatalysts prepared by a solvothermal method. The absorption band was slightly blue-shifted upon the incorporation of the gallium ions, but the intensity of the photoluminescence (PL) curves of Ga-incorporated $TiO_2$s was distinguishably smaller, with the smallest case being the 2.0 mol% Ga-$TiO_2$, which was related to the recombination between the excited electrons and holes. $H_2$ evolution from photo splitting of water over Ga-incorporated $TiO_2$ in the liquid system was enhanced, compared to that over pure $TiO_2$; particularly, the production of 5.6 mL of $H_2$ gas after 8 h when 1.5 g of the 2.0 mol% Ga-incorporated $TiO_2$ was used.

• Applied Biological Chemistry
• /
• 제20권1호
• /
• pp.123-129
• /
• 1977

효모세포벽 분해효소를 생산하는 386주(株)의 미생물을 분리하여 그중 강한 1주(株)를 선발 동정(同定)하고 선정균의 효소생산조건을 검토하여 다음과 같은 결과를 얻었다. 1. 선정한 M-10 strain은 Humicola sp.로 동정(同定) 되었다. 2. 선정균의 효소생성은 pH 6.0 $33^{\circ}C$에서 가장 양호하였다. 3. 탄소원으로서 baker's yeast 4%가 Iytic enzyme 생산에 가장좋았고 기타 laminarin과 dextrin 등이 효과적이었으며 질소원도 peptone이 다소 효과적이나 baker's yeast로서 족하였다. 4. 효소생산에 $K_2HPO_4$ 0.1%와 $MgSO_4{\cdot}7H_2O$ 0.01%의 첨가가 가장 효과적이고 기타 염류의 첨가는 효과가 없었다. 5. 선정한 배지조성에서 72시간 진탕배양으로 최고에 달하였다.

• Journal of Applied Biological Chemistry
• /
• 제58권3호
• /
• pp.209-218
• /
• 2015

Fructooligosaccharides have been mainly produced by microbial fructosyltransferases (FTase) enzymes. The present work focuses on the optimization of medium composition and cultivation parameters affecting FTase produced by Penicillium aurantiogriseum AUMC 5605 in shake flask cultivation. FTase production was optimized in two steps using DeMeo's fractional factorial design. A 1.46-fold increase in FTase production (105.4 U/mL) was achieved using the optimized culture medium consisting of (g/L): sucrose, 600; yeast extract, 10; $K_2HPO_4$, 5; $MgSO_4{\cdot}7H_2O$, 0.5; $(NH_4)_2SO_4$, 1.0 and KCl, 0.5. The obtained results showed that the maximum FTase enzyme activity was produced at initial cultivation pH values ranging from 6.0-6.5, at agitation speed of 200 rpm and using vegetative fungal cells as inoculum. Moreover, results showed that optimization of medium composition and some cultivation parameters resulted in an increase of about 93.7% in the enzyme activity than the nonoptimized cultivation conditions after 96 h of cultivation. Additionally, maximum production and specific production rates recorded 2340 U/L/h and 102 U/L/h/g cells, respectively.

• 한국생물공학회:학술대회논문집
• /
• 한국생물공학회 2000년도 춘계학술발표대회
• /
• pp.287-290
• /
• 2000

A. pullulans ATCC 42023의 pullulan생산과 형태학적인 변화를 알아보기 위해서 삼각플라스크와 회분식 발효를 이용하여 실험하였다. 삼각플라스크 내에서 초기 pH 6.5는 $11.98g/{\ell}$의 pullulan을 생산하였고, 회분식 발효에서는 pH 2.5-2.7의 범위에서 pH를 조절하면서 실험한 결과, pH 4.5에서 pullulan생산 $13.31g/{\ell}$의 최대값을 나타내었다. 그러나 균체성장은 pH 6.5에서 가장 높았다.

• 한국환경과학회지
• /
• 제30권1호
• /
• pp.57-67
• /
• 2021

Photocatalytic green energy H2 production utilizing inexhaustible solar energy has been considered as a potential solution to problems of energy scarcity and environmental contamination. However, the design of a cost-effective photocatalyst using simple synthesis methodology is still a grand challenge. Herein, a low-cost transition metal, Cu-loaded one-dimensional TiO2 nanorods (Cu/TNR) were fabricated using an easy-to-use synthesis methodology for significant H2 production under simulated solar light. X-ray photoelectron spectral studies and electron microscopy measurements provide evidence to support the successful formation of the Cu/TNR catalyst under our experimental conditions. UV-vis DRS studies further demonstrate that introducing Cu on the surface of TNR substantially increases light absorption in the visible range. Notably, the Cu/TNR catalyst with optimum Cu content, achieved a remarkable H2 production with a yield of 39,239 µmol/g after 3 h of solar light illumination, representing 7.4- and 27.7-fold enhancements against TNR and commercial P25, respectively. The notably improved H2 evolution activity of the target Cu/TNR catalyst was primarily attributed to its excellent separation and efficiently hampered recombination of photoexcited electron-hole pairs. The Cu/TNR catalyst is, therefore, a potential candidate for photocatalytic green energy applications.

• Animal Bioscience
• /
• 제37권2_spc호
• /
• pp.323-336
• /
• 2024

Molecular hydrogen (H₂) and formate (HCOO^-) are metabolic end products of many primary fermenters in the rumen ecosystem. Both play a vital role in fermentation where they are electron sinks for individual microbes in an anaerobic environment that lacks external electron acceptors. If H₂ and/or formate accumulate within the rumen, the ability of primary fermenters to regenerate electron carriers may be inhibited and microbial metabolism and growth disrupted. Consequently, H₂- and/or formate-consuming microbes such as methanogens and possibly homoacetogens play a key role in maintaining the metabolic efficiency of primary fermenters. There is increasing interest in identifying approaches to manipulate the rumen ecosystem for the benefit of the host and the environment. As H₂ and formate are important mediators of interspecies interactions, an understanding of their production and utilization could be a significant starting point for the development of successful interventions aimed at redirecting electron flow and reducing methane emissions. We conclude by discussing in brief ruminant methane mitigation approaches as a model to help understand the fate of H₂ and formate in the rumen ecosystem.

• Journal of Microbiology and Biotechnology
• /
• 제22권3호
• /
• pp.400-406
• /
• 2012

To improve the hydrogen yield from biological fermentation of organic wastewater, a co-culture system of dark- and photo-fermentation bacteria was investigated. In a pure-culture system of the dark-fermentation bacterium Clostridium butyricum, a pH of 6.25 was found to be optimal, resulting in a hydrogen production rate of 18.7 ml-$H_2/l/h$. On the other hand, the photosynthetic bacterium Rhodobacter sphaeroides could produce the most hydrogen at 1.81mol-$H_2/mol$-glucose at pH 7.0. The maximum specific growth rate of R. sphaeroides was determined to be 2.93 $h^{-1}$ when acetic acid was used as the carbon source, a result that was significantly higher than that obtained using either glucose or a mixture of volatile fatty acids (VFAs). Acetic acid best supported R. sphaeroides cell growth but not hydrogen production. In the co-culture system with glucose, hydrogen could be steadily produced without any lag phase. There were distinguishable inflection points in a plot of accumulated hydrogen over time, resulting from the dynamic production or consumption of VFAs by the interaction between the dark- and photo-fermentation bacteria. Lastly, the hydrogen production rate of a repeated fed-batch run was 15.9 ml-$H_2/l/h$, which was achievable in a sustainable manner.

• 한국수소및신에너지학회논문집
• /
• 제17권4호
• /
• pp.395-402
• /
• 2006

Iodine-sulfur(IS) hydrogenation production process consists of three sections, which are so called a Bunsen reaction section, a HI decomposition section and a $H_2SO_4$ decomposition section as a closed cycle. For highly efficient operation of a Bunsen reaction section, we investigated the phase separation characteristics of $H_2SO_4-HI-H_2O-I_2$ system into two liquid phases($H_2SO_4$-rich phase and $HI_x$-rich phase) in the high temperature ranges, mainly from 353 to 393 K, and in the $H_2SO_4/HI/H_2O/I_2$ molar ratio of $1/2/14{\sim}30/0.3{\sim}13.50$. The desired results for the minimization of impurities in each phase were obtained in conditions with the higher temperature and the higher $I_2$ molar composition. On the basis of the distribution of $H_2O$ to each phase, it is appeared that the affinity between $HI_x$ and $H_2O$ was more superior to that between $H_2SO_4$ and $H_2O$.

• 대한약리학회지
• /
• 제31권1호
• /
• pp.115-122
• /
• 1995

C5a 또는 PMA에 의하여 활성화된 호중구에서의 superoxide와 HOCl 생성에 나타내는 staurosporine, genistein과 pertussis toxin의 효과를 관찰하였다. C5a에 의한 superoxide과 $H_2O_2$의 생성은 staurosporine, genistein과 pertussis toxin에 의하여 억제되었다. PMA의 자극효과는 staurosporine에 의하여 억제되었으나 pertussis toxin에 의하여 영향을 받지 않았으며, 한편 이는 genistein에 의하여 더 촉진되었다. Staurosporine, genistein은 sodium fluoride에 의한 superoxide 생성을 억제 하였으나 pertussis toxin은 영향을 나타내지 않았다. PMA에 의한 $H_2O_2$의 생성은 staurosporine에 의하여 억제되었으나 pertussis toxin은 영향을 나타내지 않았다. Genistein은 PMA에 의한 $H_2O_2$의 생성에 자극효과를 나타내지 않았다. Staurosporine과 pertussis toxin은 C5a 또는 PMA에 의한 HOCl 생성을 억제하였으나, 이에 반하여 genistein은 자극하였다. C5a와 PMA에 의한 myeloperoxidase 유리는 genistein에 의하여 억제되었나, pertussis toxin의 효과는 나타나지 않았다. Staurosporine은 유리에 대한 PMA의 자극효과에 영향을 주지 않았다. Myeloperoxidase 활성은 genistein에 의하여 현저하게 증가되었으나 staurosporine과 pertussis toxin의 영향은 받지 않았다. 이상의 결과는 호중구의 respiratory burst가 protein kinase C와 protein tyrosine kinase에 의하여 조절된다고 제시한다. Protein kinase C의 직접적인 자극에 따른 superoxide 생성은 protein tyrosine kinase의 영향을 역으로 받을 것으로 추정된다. Genistein은 아마도 myeloperoxidase를 활성화하여 HOCl 생성을 촉진할 것으로 시사된다.

• 한국미생물·생명공학회지
• /
• 제43권3호
• /
• pp.236-240
• /
• 2015

초고온성 고세균 Thermococcus onnurineus NA1은 개미산, 일산화탄소, 또는 전분 등을 이용해서 수소를 생산하는 것으로 알려져 있다. 본 연구에서는 T. onnurineus NA1의 고정화 세포를 이용한 수소생산을 고찰하였다. 고정화 실험결과, T. onnurineus NA1은 표면에 아민기가 코팅된 규조토 담체에 정전기적 인력에 의해 효과적으로 고정화되었고, 1 g의 담체에 고정화 될 수 있는 최대 세포의 양은 71.7 mg-dcw로 확인되었다. 고정화 세포를 이용한 세 번의 반복회분식 배양을 통해 개미산으로부터 수소생산 특성을 고찰하였고, 그 결과 배양이 반복됨에 따라 고정화 세포 농도의 증가에 기인하여 초기수소생산속도가 2.3 에서 4.0 mmol l⁻¹ h⁻¹로 상당량 증가됨이 관찰되었다. 따라서, T. onnurineus NA1의 고정화세포 시스템은 수소생산을 위한 좋은 대안이 될 수 있을 것으로 사료된다. 본 연구는 초고온성 고세균의 고정화세포를 수소생산에 적용한 첫 번째 사례이다.