• 한국수소및신에너지학회논문집
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• 제21권2호
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• pp.136-142
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• 2010

Photobiological $H_2$ production was compared using purple non-sulfur bacteria Rhodobacter sphaeroides KD131 in the medium containing various organic acids as the carbon source and electron doner under illumination of $110\;W/m^2$ using halogen lamp at $30^{\circ}C$. The organic acids used were 0~120 mM acetate, butyrate, lactate and malate. Initial pH 7.0 and cell concentration 1.0 at 660nm were increased to pH 8 and 4.4~5.1, respectively during 24hrs of photo-fermentation when lactate and malate were used. However, acetate and butyrate increased pH to 9 and cell concentration to 3.2~3.9 of malate at the same experimental conditions. Optimum ranges of organic acids concentration and carbon/nitrogen ratio were 30~60 mM and 10~20, respectively. When malate was used as the substrate, maximum $H_2$ production 1.1 ml $H_2$/ml broth, which is equivalent to 1.97 mol $H_2$/mol malate was observed.

• Journal of Microbiology and Biotechnology
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• 제31권10호
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• pp.1393-1400
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• 2021

Acetone-butanol-ethanol (ABE) fermentation by the anaerobic bacterium Clostridium acetobutylicum has been considered a promising process of industrial biofuel production. Phosphotransbutyrylase (phosphate butyryltransferase, PTB) plays a crucial role in butyrate metabolism by catalyzing the reversible conversion of butyryl-CoA into butyryl phosphate. Here, we report the crystal structure of PTB from the Clostridial host for ABE fermentation, C. acetobutylicum, (CaPTB) at a 2.9 Å resolution. The overall structure of the CaPTB monomer is quite similar to those of other acyltransferases, with some regional structural differences. The monomeric structure of CaPTB consists of two distinct domains, the N- and C-terminal domains. The active site cleft was formed at the interface between the two domains. Interestingly, the crystal structure of CaPTB contained eight molecules per asymmetric unit, forming an octamer, and the size-exclusion chromatography experiment also suggested that the enzyme exists as an octamer in solution. The structural analysis of CaPTB identifies the substrate binding mode of the enzyme and comparisons with other acyltransferase structures lead us to speculate that the enzyme undergoes a conformational change upon binding of its substrate.

• KSBB Journal
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• 제20권6호
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• pp.443-446
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• 2005

음식물 쓰레기로부터의 연속 수소 생성 실험을 다양한 수리학적 체류시간(HRT; 18, 21, 24, 30, 36, 42 h)에서 수행하였다. 음식물쓰레기는 분쇄와 알칼리 처리를 거쳐 27.0 g COD/L(average VS 4.4%)의 농도로 fed-batch 형태로 주입되었으며, 반응조 내의 pH는 $5.3{\pm}0.1$ 이상으로 유지되었다. 126일 간의 운전을 통해 유기성 폐기물로부터의 연속 수소 생성이 안정적으로 진행될 수 있음을 확인하였다. 수소 생성 효율은 HRT에 따라 변하였으며, 30 h에서 가장 높은 수치를(25.8 mL $H_2/g\;VS_{added}$, 0.36 mol $H_2/mol\;hexose_{added}$, 0.91 L $H_2/L/d$) 보였다. 대부분의 조건에서 가장 양이 많은 부산물은 노말부티르산이었으며, 수소생성이 증가함에 따라 노말부티르산의 생성이 증가하였다. 이소프로판을 역시 수소 생성과 관련이 있는 나타났다. 반면, 아세트산의 생성량은 수소생성과 반대되는 경향을 보여 수소 소모 아세트산 생성 경로로 발생되는 양이 많았다고 사료된다. 한편 산발효 효율은 $53.3{\sim}65.7%$인 것으로 나타나 기존 산 발효를 수소발효가 대체할 수 있음을 확인하였다.

• Asian-Australasian Journal of Animal Sciences
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• 제24권4호
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• pp.471-478
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• 2011

The objectives were to compare the ability of various rumen microbial fractions to reduce nitrate and to assess the effect of nitrate on in vitro fermentation characteristics. Physical and chemical methods were used to differentiate the rumen microbial population into the following fractions: whole rumen fluid (WRF), protozoa (Pr), bacteria (Ba), and fungi (Fu). The three nitrogen substrate treatments were as follows: no supplemental nitrogen source, nitrate or urea, with the latter two being isonitrogenous additions. The results showed that during 24 h incubation, WRF, Pr and Ba fractions had an ability to reduce nitrate, and the rate of nitrate disappearance for the Pr fraction was similar to the WRF fraction, while the Ba fraction needed an adaptation period of 12 h before rapid nitrate disappearance. The WRF fraction had the greatest methane ($CH_4$) production and the Pr fraction had the greatest prevailing $H_2$ concentration (p<0.05). Compared to the urea treatment, nitrate diminished net gas and $CH_4$ production during incubation (p<0.05), and ammonia-N ($NH_3$-N) concentration (p<0.01). Nitrate also increased acetate, decreased propionate and decreased butyrate molar proportions (p<0.05). The Pr fraction had the highest acetate to propionate ratio (p<0.05). The Pr fraction as well as the Ba fraction appears to have an important role in nitrate reduction. Nitrate did not consistently alter total VFA concentration, but it did shift the VFA profile to higher acetate, lower propionate and lower butyrate molar proportions, consistent with less $CH_4$ production by all microbial fractions.

• Applied Biological Chemistry
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• 제44권1호
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• pp.1-6
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• 2001

본 연구에서는 Ttichoplusia ni 세포의 apoptosis 유도 및 억제 현상의 기초연구를 수행하였다. Apoptosis 유도제로 알려진 hygromycin B에 의한 세포 성장 저해는 $200\;{\mu}/ml$의 수준에서부터 나타났고, $400\;{\mu}/ml$ hygromycin B를 처리한 세포에서는 배양 후 2일부터 DNA가 분절되어지는 것을 확인할 수 있었다. 그러나 dexamethasone과 sodium butyrate를 첨가시 세포성장은 저해되었지만 DNA 분절현상이 보이지 않아 apoptosi의 유발여부를 확인할 수 없었다. 그리고 caspase 기능억제제의 apoptosis 지연효과를 보기 위해 $200\;{\mu}/ml$ hygromycin B로 apoptosis를 유발한 상태에서 Ac-DEVD-CHO를 첨가하여 세포성장을 비교해 본 결과 이 저해제에 의해 약 36%정도 apoptosis가 억제되었음을 확인하였다. N-acetylcysteine의 경우도 apoptosis지연 효과가 있었다. Bcl_계에 속하는 anti-apoptotic 유전자의 발현연구로서 apoptosis 저해 단백질인 bcl-2 유전자를 곤충세포에 형질전환시킨 후 이 단백질이 한시적으로 발현되는 것을 western blot분석법으로 확인하였으며 apoptosis가 지연된 곤충세포주의 개발이 가능하다는 결론을 보였다.

• 한국수소및신에너지학회논문집
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• 제22권6호
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• pp.765-771
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• 2011

This study was conducted to investigate the effect of heat treatment on the start-up performance for anaerobic hydrogen fermentation of food waste. The result showed that hydrogen production was $0.61{\pm}0.31$ mol $H_2$/mol hexose with heat-treatment of food waste at $70^{\circ}C$ for 60 min whereas it was $0.36{\pm}0.31$ mol $H_2$/mol hexose without heat-treatment of one. The heat treatment of food waste enhanced hydrogen yield due probably to the increase of hydrolysis as well as the decrease of non-hydrogen fermentation microorganisms. The removal efficiency of carbohydrate in reactors regardless of heat treatment of food waste maintained over 90%. The hydrogen conversion efficiency from food waste was 1.7-6.3% with heat-treatment whereas it was 0.7-4.5% without heat-treatment. At the time of switchover from batch to continuous operation, lactate concentration was high compared to the n-butyrate concentration in anaerobic hydrogen fermentation reactor without heat-treatment. Anaerobic hydrogen fermentation of food waste with heat treatment was stable in start-up periods because lactate concentration could be maintained at a relatively low compared to n-butyrate concentration due to the decrease of non-hydrogen fermentation microorganisms.

• 한국미생물·생명공학회지
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• 제19권5호
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• pp.536-541
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• 1991

유당발효 효모인 Kluyveromyces lactis ATCC 8585를 이용하여 유청에서 과일향 풍미성분의 생산성을 향상시키기 위하여 3차에 걸처 NTG를 처리하고 geraniol의 항균력에 내성을 지니는 변이주 중 모균주에 비해 yeasty-flavor는 약하나 fruity-flavor가 강한 변이주를 선발하고 K.lactis 450 K라 명명하였다. 3일간 배양시킨 발효액을 pentane-dichloromethane(2:1)용매로 추출하여 얻은 oleoresin을 gas chromatography로 분석한 결과, 모균주보다 변이주가 더 많은 종류와 양의 향기성분을 생산한 것으로 나타났다.

• Journal of Microbiology and Biotechnology
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• 제13권6호
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• pp.926-936
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• 2003

Overexpression of human Bcl-2 protein in recombinant Chinese hamster ovary (rCHO) cells producing humanized antibody (SH2-0.32) considerably suppressed sodium butyrate (NaBu)-induced apoptosis during batch culture by using commercially available serum-free medium, which extended the culture longevity. Due to the extended culture longevity provided by the anti-apoptotic effect of Bcl-2 overexpression, the final antibody concentration of 14C6-bcl-2 culture (Bcl-2 high producer, $23\;\mu\textrm{g}\;ml^{-1}$) was 2 times higher than that of the $SH2-0.32-{\Delta}bcl-2$ culture (cells transfected with bcl-2-deficient plasmid, $10.5\;\mu\textrm{g}\;ml^{-1}$) in the presence of NaBu. To determine the effect of NaBu/Bcl-2 overexpression on the molecular integrity of protein products, antibodies purified from 14C6-bcl-2 and $SH2-0.32-{\Delta}bcl-2$ cultures in the presence of NaBu were characterized by using various molecular assay systems. For comparison, antibody purified from the parental rCHO cell culture (SH2-0.32) in the absence of NaBu was also characterized. No significant changes in molecular weight of antibodies could be observed by SDS-PAGE. From GlycoSep-N column analysis, it was found that the core oligosaccharide structure ($GlcNAc_2Man_3GlcNAc_2$) was not affected by NaBu/Bcl-2 overexpression, while the microheterogeneity of N-linked oligosaccharide structure was slightly affected. Compared with the antibody produced in the absence of NaBu, the proportion of neutral oligosaccharides was increased from 10% (14C6-bcl-2) to 16% ($SH2-0.32-{\Delta}bcl-2$) in the presence of NaBu, which was accompanied by the reduced proportion of acidic oligosaccharides, especially of monosialylated and disialylated forms. The changes in microheterogeneous oligoformal structures of antibody in turn affected the mobility of antibody isoforms in isoelectric focusing (IEF), resulting in the occurrence of some more basic antibody isoforms produced in the presence of NaBu. However, the antigen-antibody binding properties were not changed by alteration of glycosylation pattern. The competitive enzyme-linked immunosorbent assay (ELISA) showed that the antibody produced by NaBu/Bcl-2 overexpression maintained its antigen-antibody binding properties with binding affinity of about $2.5{\times}10^9{\;}M^{-1}$. Taken together, no significant effects of NaBu/Bcl-2 overexpression on the molecular integrity of antibodies, produced by using serum-free medium, could be observed by the molecular assay systems.

• Asian-Australasian Journal of Animal Sciences
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• 제12권8호
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• pp.1215-1221
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• 1999

Twelve rumen fistulated cross-bred calves were divided into three groups and fed wheat straw and concentrate mixture according to their maintenance requirement. Animals in group II and III were fed 50 and 100mg rumensin per day, in addition to basal feed. Supplementation of rumensin in the diet decreased the dry matter intake significantly (p<0.05) along with a significant decrease in the straw intake. Digestibility coefficients of all the nutrients were not affected significantly except that of CF digestibility which was lower (p<0.05) in groups II and III as compared to group I. Among N-parameters in the rumen fluid, mean $NH_3-N$ was significantly lower in groups II and III (19.13 and 18.63 mg N/100 ml respectively) than in group I (22.68); total-N and TCA-ppt-N did not differ among the three groups. Total VFA concentration did also not differ among the three groups, however, propionate increased from 24.33 molar % to 32.73 while acetate and butyrate decreased respectively from 65.85 to 58.81% and 9.79 to 8.46%. Total VFA, bacteria and protozoa production rates were not affected significantly due to rumensin in diet. Methane production per kg DDM as well as % of methane in total gas were reduced at both the levels of rumensin on different concentrate ratios with wheat straw as roughage. Similar trend was also observed with rice straw and concentrate mixture as substrate with rumensin addition.

• 상하수도학회지
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• 제14권2호
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• pp.196-206
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• 2000

Methanogenesis and denitrification in an upflow sludge baffled filter (UBF) reactor were studied using glucose as a fermentative substrate. Experiments were carried out to investigate how to reduce ammonification by changing alkalinity and $COD/NO_3-N$ ratio. Characteristics of granular sludges were examined by specifics methanogenic activity(SMA) and specific denitrification rate(SDR) tests. Microstructures of granules were examined using a scanning electron microscopy(SEM). It was found that COD was removed efficiently owing to the diverse microorganisms. In nitrate conversion, not only $COD/NO_3-N$ ratio but also influent alkalinity played important role in the ratio of denitrification and ammonification of nitrate. This reactor achieved over 95% COD and 99% nitrate removal efficiencies when influent contained 4000 mgCOD/L and $700mgNO_3-N/L$ at the hydraulic retention time of 24 hours. As $COD/NO_3-N$ ratio decreased, granular methanogenic activities using acetate and butyrate as substrates increased while activities using propionate and glucose decreased. There were three types in granules according to the surface color; gray, yellowish gray, and black. Gray or yellowish gray-colored granules were composed two layers, which were composed of black inner side and gray or yellowish gray surface substances. SEM illustrated that both were rod-type and cocci-type microorganisms resembling Methanothrix sp. and Methanococci sp. This study showed that by controlling the influent alkalinity and $COD/NO_3-N$ ratio, ammonification and denitrification could be manipulated.