• 문화기술의 융합
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• 제9권3호
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• pp.587-592
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• 2023

CoCl₂·6H₂O 수용액을 결정성셀룰로오스에 함침시켜 건조한 후, 하소, 소성을 통하여 산화코발트(Co₃O₄·CoO) 초미세입자를 합성하였다. 합성된 코발트 산화물 입자의 결정구조 및 표면구조를 주사전자현미경(SEM)과 X-선회절분석(XRD)으로 조사하였다. CoCl₂·6H₂O 수용액을 함침시키는 매개체로 사용한 결정성셀룰로오스(crystalline cellulose)는 470℃ 정도에서 열분해 되었고, Co₃O₄ 결정상은 350℃에서 생성되기 시작하였다. Co₃O₄ 결정상은 500℃까지 유지되었으며, 500℃ 이상의 온도에서는 CoO 결정상으로 변화하는 것을 알 수 있었다. 열처리 온도가 증가함에 따라 산화코발트 입자의 크기가 커지는 현상이 나타났으며, 900℃ 이상의 온도에서는 입자간 용융이 일어나는 것이 관찰되었다. 하소온도 700℃ 이하의 온도에서 입자크기 2-10㎛의 Co₃O₄와 CoO의 초미세입자가 생성되는 것을 확인하였다.

• Journal of the Korean Wood Science and Technology
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• 제25권3호
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• pp.83-95
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• 1997

The degradation mode of lignocellulose by anaerobic ruminal cellulolytic bacterium Ruminococcus albus F-40 was investigated. Birchwood holocellulose and filter paper were incubated as the sole carbohydrate sources with using the Hungate techniques. After 2 or 4 days of incubation, samples were employed for chemical and electron microscopic evaluations. The degradation rate of cellulosic substrates and the adhesion rate of bacteria to the substrates increased proportionally with the decrease of relative crystallinity of cellulose, indicating the preferential breakdown of amorphous cellulose, by this bacterium. X-ray diffraction analyses and polarized light microscopy showed, however, that crystalline cellulose was also degraded by R. albus. FT-IR spectra indicated that not only cellulose but hemicellulose was also degraded by this bacterium. Electron microscopic investigations showed the protuberant structures on the surface of R. albus. These structures were much more significant when bacterial cells were grown in the media containing insoluble substrates, such as cellulose, indicating clearly that bacterial protuberant structures were induced by the substrates. Protuberant structures extended from the bacterial cells adhered tightly to the substrates and numerous vesicles covered the surface of cellulosic substrates affected. Cellulosome-like structures were distributed on the cellulose matrix. Electron microscopic works showed that diverse surface organells of R. albus were involved in the degradation of cellulosic materials. SEM examinations showed the breakdown of cellulose by R. albus was proceeded by severeal routes : short fiber formation, defibrillation and destrafication of cellulose microfibril.

• Journal of Microbiology and Biotechnology
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• 제18권3호
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• pp.404-409
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• 2008

The brown-rot basidiomycete Fomitopsis palustris is known to degrade crystalline cellulose (Avicel) and produce three major cellulases, exoglucanases, endoglucanases, and ${\beta}$-glucosidases. A gene encoding endoglucanase, designated as cel12, was cloned from total RNA prepared from F. palustris grown at the expense of Avicel. The gene encoding Cel12 has an open reading frame of 732 bp, encoding a putative protein of 244 amino acid residues with a putative signal peptide residing at the first 18 amino acid residues of the N-terminus of the protein. Sequence analysis of Cel12 identified three consensus regions, which are highly conserved among fungal cellulases belonging to GH family 12. However, a cellulose-binding domain was not found in Cel12, like other GH family 12 fungal cellulases. Northern blot analysis showed a dramatic increase of cel12 mRNA levels in F. palustris cells cultivated on Avicel from the early to late stages of growth and the maintenance of a high level of expression in the late stage, suggesting that Cel12 takes a significant part in endoglucanase activity throughout the growth of F. palustris. Adventitious expression of cel12 in the yeast Pichia pastoris successfully produced the recombinant protein that exhibited endoglucanase activity with carboxymethyl cellulose, but not with crystalline cellulose, suggesting that the enzyme is not a processive endoglucanase unlike two other endoglucanases previously identified in F. palustris.

• 미생물학회지
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• 제36권3호
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• pp.181-186
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• 2000

Clostridium thermocellum이 생성하는 섬유소분해 효소복합체인 cellulosome은 26개 의 서로 다른 단백질로 구성되어 있으며 그 구성물질로서 calcium을 포함하고 있다. 견고한 구조의 이 복합체에서 구성단백질을 분리하여 그 기능을 연구할 목적으로 이 복합체를 해체 (dissociation)하려 시도하였다. 이 복합체는 calcium을 제거하였을 대 해체되었다. 해체된 구성 단백질들은 MonoQ column chromatogrphy에 의해 구조단백질인 CipA를 포함한 분획, 91 kDa(CelK-tr), 60 kDa 과 57 kDa 단백질로 구성된 분획과 주로 46 kDa(CelA-tr), 또는 71 kDa(CelS-tr) 단백질을 포함하는 분획들로 크게 분리되었다. 대부분의 분획들은 crystalline cellulose 분해 활성을 보였다. 순수 분리된 71 kDa 단백질은 $60^{\circ}C$~$70^{\circ}C$에서 섬 유소 분해시 calcium에 의존적이었으나 46 kDa 단백질은 그렇지 않았다. 46 kDa 단백질은 cellodextrin을 celloviose 및 cellotriose 단위로 절단하며 cellotetraose 로부터 glucose가 생 성되는 것이 관찰되었다. Cellulosome의 섬유소분해 최성 산물이 cellobiose인 것을 고려할 때 개개 구성단백질의 활성이 이 효소 복합체내에서 조절되어 있음을 알 수 있다.

• 산업식품공학
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• 제14권2호
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• pp.118-126
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• 2010

The fibrous material fraction as a by-product from the commercial aloe vera gel processing was obtained and freeze dried. The physicochemical characteristics such as the proximate composition, crystalline/surface structures and several physical functionalities including the water holding capacity (WHC), swelling capacity (SW), oil holding capacity (OHC), emulsion/foam properties and viscosity properties of this powdered sample (100 mesh) were investigated and analyzed by comparison with commercial $\alpha$-cellulose as a reference sample. The total dietary fiber content of powdered sample was very high as much as 87.5%, and the insoluble dietary and soluble dietary fiber content ratios were 77.6 and 22.4%, respectively. The FT-IR spectrum of powdered sample showed a typical polysaccharide property and exhibited a x-ray diffraction pattern for cellulose III and IV like structure. SW (8.24${\pm}$0.15 mL/g), WHC(6.40${\pm}$0.19 g water/g solid) and OHC(10.32${\pm}$0.29 g oil/g solid) of freeze dried aloe cellulose were about 3.3, 1.4 and 2 times higher than those of commercial $\alpha$-cellulose, respectively. Aloe cellulose (~2%, w/v) alone had no foam capacity while improved the foam stability of protein solution (1% albumin+0.5% $CaCl_{2}$) by factor of 300%. Emulsion capacity of 2%(w/v) aloe cellulose was about 70% level of 0.5%(w/v) xanthan gum, but its emulsion stability was about 1.2 times higher than that of xanthan gum. Also, aloe cellulose containing CMC (carboxyl methyl cellulose) of 0.3%(w/v) showed a very good dispersity. Aloe cellulose dispersion of above 1%(w/v) exhibited higher pseudoplasticity and concentration dependence than those of $\alpha$-cellulose dispersion, indicating the viscosity properties for new potential usage such as an excellent thickening agent.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2006년도 PAN PACIFIC CONFERENCE vol.1
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• pp.43-49
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• 2006

The surface and pore structure of cellulose fibers have a significant impact on the properties and performance in applications. Cellulase enzymatic hydrolysis of cellulose fibers can result in changes to the surface and pore structure thus providing a useful tool for fiber modification. This research characterizes these changes using various test methods such as fiber dimension, water retention value, hard-to-remove water content, freezing and non-freezing bound water content, polymer adsorption, and crystallinity index. For a high-dosage enzyme treatment (0.10 g/g), the fiber length was significantly decreased and the fibers were 'cut' in the cross direction, not in the axial direction. The swelling capacities as measured by the WRV and HR water content increased for the high-dosage treatment. Three independent measurements (non-freezing bound water, polymer adsorption, and crystallinity index) are in good agreement with the statement that the amorphous regions of cellulose fibers are a more readily available substrate relative to crystalline regions. Based on the experimental results obtained herein, a model was proposed to explain surface and pore structure modification of cellulose fibers via enzymatic treatment.

• Journal of Microbiology and Biotechnology
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• 제17권5호
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• pp.800-805
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• 2007

Two endoglucanases with processive cellulase activities, produced from Fomitopsis palustris grown on 2% microcrystalline cellulose(Avicel), were purified to homogeneity by anion-exchange and gel filtration column chromatography systems. SDS-PAGE analysis indicated that the molecular masses of the purified enzymes were 47 kDa and 35 kDa, respectively. The amino acid sequence analysis of the 47-kDa protein(EG47) showed a sequence similarity with fungal glycoside hydrolase family 5 endoglucanase from the white-rot fungus Phanerochaete chrysosporium. N-terminal and internal amino acid sequences of the 35-kDa protein(EG35), however, had no homology with any other glycosylhydrolases, although the enzyme had high specific activity against carboxymethyl cellulose, which is a typical substrate for endoglucanases. The initial rate of Avicel hydrolysis by EG35 was relatively fast for 48 h, and the amount of soluble reducing sugar released after 96 h was $100{\mu}g/ml$. Although EG47 also hydrolyzed Avicel, the hydrolysis rate was lower than that of EG35. Thin layer chromatography analysis of the hydrolysis products released from Avicel indicated that the main product was cellobiose, suggesting that the brown-rot fungus possesses processive EGs capable of degrading crystalline cellulose.

• 미생물학회지
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• 제25권4호
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• pp.297-297
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• 1987

A $C_{1}$ enriched cellulase fraction was separated from culture filtrate of anaerobic Clostridium thermocellum by hydroxyapatite column chromatography. The separated fraction showed strong synergistic action with $C_{x}$ component (endo-$\beta$-1, 4-glucanase) in digestion of crystalline cellulose, similar to the other aerobic cellulolytic microorganisms. Unlike the $C_{x}$ component the $C_{1}$ enriched fraction was rapidly inactivated by oxidation at the atmospheric condition. The enzyme activity was significantly enhanced by the addition of reducing agents, especially $\beta$-mercaptoethanol, which indicates that a $C_{1}$ component has a lot of sulfhydryl groups essential for the enzyme activity. The effect of metal ions on $C_{1}$ activity was also investigated. The $C_{1}$ fraction was found to be thermally stable compare to endo-$\beta$-1,4-glucanase. Optimal temperature and pH were found to be 60.deg.C and 6.0, respectively.

• 한국의류학회지
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• 제45권5호
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• pp.866-880
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• 2021

This study aimed to ex situ colorize laccase-entrapped bacterial cellulose (BC) with natural phenolic dyes, namely,madder, turmeric, and cochineal, and to determine the effect of laccase entrapment on the dyeability of BC using color strength (K/S) analysis. Results showed that laccase entrapment improved the dyeability of BC and that pre-entrapment was the most effective method, compared with meta-entrapment and post-entrapment methods. In addition, surface characterizations confirmed the successful entrapment of laccase inside the BC nanostructure and retention of the cellulosic and crystalline structures of BC. The washing durability test confirmed that the K/S value of BC had improved after laccase entrapment. Furthermore, laccase-entrapped BC colorized with cochineal dye had the highest washing durability due to the high molecular weight of cochineal dyerelative to the other dyes. This study suggests a novel method for enhancing the dyeability and washing durability of BC colorized ex situ with natural phenolic dyes by laccase entrapment.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 춘계학술대회 논문집
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• pp.612-613
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• 2009