Enzymatic Conversion of Cellulose to Glucose: Present State of the Art and Potential

Klyosov, Anatole A.; Rabinowitch, M. L.

doi:10.1007/978-1-4684-3719-5_3

Cited by 24 publications

(8 citation statements)

References 28 publications

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“…Avicelase activity was determined by analyzing reducing sugars released after 60 min of enzyme reaction with Avicel (5 mg/mL) at pH 5.0 and 40°C [14]. Reducing sugars were analyzed by the Somogyi method [26].The endoglucanase viscometric activity was determined in a thermostated Ostwald viscometer at pH 5.0 and 40°C using 5 mL of the CMC solution (5 mg/mL) in 0.1 M Na-acetate buffer [27]. Activities against p-NP-β-cellobioside and p-NP-β-lactoside were determined at pH 5.0 and 40°C by measuring p-nitrophenol released as described elsewhere [14].…”

Section: Enzyme Activity Assaysmentioning

confidence: 99%

“…In the case of purified cellulases, in order to eliminate the effect of cellobiose inhibition on the kinetics and to convert all cellooligosaccharides to glucose, the hydrolysis was carried out in the presence of purified β-glucosidase from A. japonicus (0.5 U/mL) [21]. Glucose was measured by the glucose oxidase-peroxidase method [27]. The kinetic experiments were carried out in duplicates.…”

Section: Progress Kinetics Of Avicel Hydrolysismentioning

confidence: 99%

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Cellulases of Penicillium verruculosum

Morozova

Gusakov

Андрианов

et al. 2010

Biotechnology Journal

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Nine major cellulolytic enzymes were isolated from a culture broth of a mutant strain of the fungus Penicillium verruculosum: five endo-1, 4-beta-glucanases (EGs) having molecular masses 25, 33, 39, 52, and 70 kDa, and four cellobiohydrolases (CBHs: 50, 55, 60, and 66 kDa). Based on amino acid similarities of short sequenced fragments and peptide mass fingerprinting, the isolated enzymes were preliminary classified into different families of glycoside hydrolases: Cel5A (EG IIa, 39 kDa), Cel5B (EG IIb, 33 kDa), Cel6A (CBH II, two forms: 50 and 60 kDa), Cel7A (CBH I: 55 and 66 kDa), Cel7B (EG I: 52 and 70 kDa). The 25 kDa enzyme was identical to the previously isolated Cel12A (EG III). The family assignment was further confirmed by the studies of the substrate specificity of the purified enzymes. High-molecular-weight forms of the Cel6A, Cel7A, and Cel7B were found to possess a cellulose-binding module (CBM), while the catalytically active low-molecular-weight forms of the enzymes, as well as other cellulases, lacked the CBM. Properties of the isolated enzymes, such as substrate specificity toward different polysaccharides and synthetic glycosides, effect of pH and temperature on the enzyme activity and stability, adsorption on Avicel cellulose and kinetics of its hydrolysis, were investigated.

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Section: Enzyme Activity Assaysmentioning

confidence: 99%

Section: Progress Kinetics Of Avicel Hydrolysismentioning

confidence: 99%

Cellulases of Penicillium verruculosum

Morozova

Gusakov

Андрианов

et al. 2010

Biotechnology Journal

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“…Accepted for publication September 2,1986 The process of enzymatic cellulose saccharification has been widely investigated recently since cellulose is the most abundant renewable resource and glucose formed as a product of hydrolysis can be converted to ethanol, microbial products, and other chemicals. The efficiency of enzymatic cellulose hydrolysis is known to be affected by many factors related to the source of the cellulase preparation,14 composition and structure of cellulosic material, the method of its pretreatment,'-1° process conditions,"I2 and the reactor design.'",."…”

mentioning

confidence: 99%

Factors affecting the enzymatic hydrolysis of cellulose in batch and continuous reactors: Computer simulation and experiment

Gusakov

Sinitsyn

Klyosov

1987

Biotech & Bioengineering

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The process of enzymatic cellulose saccharification has been widely investigated recently since cellulose is the most abundant renewable resource and glucose formed as a product of hydrolysis can be converted to ethanol, microbial products, and other chemicals. The efficiency of enzymatic cellulose hydrolysis is known to be affected by many factors related to the source of the cellulase preparation,14 composition and structure of cellulosic material, the method of its pretreatment,'-1° process conditions,"I2 and the reactor design.'",." Since these factors are closely interrelated, a complex study of hydrolysis and a quantitative estimation of the role of the individual factors affecting its efficiency are needed to optimize the process.P r e v i o~s l y , '~, '~ we have developed mathematical models for the enzymatic hydrolysis of cellulose by cellulases from Trichodermu longibrachiatum in batchstirred and plug-flow column reactors. The model for the batch reactor process14 allows for the component composition of the cellulase preparation, inhibition by hydrolysis products (glucose and cellobiose), decrease in cellulose reactivity, and enzyme inactivation in the course of hydrolysis. The column reactor model" also takes into account the adsorption and distribution of cellulases in layers of the reactor as well as the redistribution of the enzymes during the process.In the present communication, the models are used for the quantitative evaluation of factors affecting the enzymatic hydrolysis of cellulose in batch-stirred and continuous plug-flow column reactors. Their role and * To whom correspondence should be addressed. relative contribution to the process kinetics are discussed. MATERIALS AND METHODSA crude cellulase preparation from the fungus Ti+ chodermu longihruchiutum, obtained from a culture filtrate by precipitation with ethanol, having a filter paper activityI6 (FPA) of 28 IU/g (5OoC, pH 4.8), an endoglucanase a~tivity'.'~ of 76 IUig (4OoC, pH 4.3, and a cellobiase activity' of 0.5 IU/g (4OoC, pH 4.5) was used. Sulfite delignified cellulose from cotton stalks with an 8043% degree of ~rystallinity','~ was used as a substrate.The hydrolysis products were analyzed by high-performance liquid chromatography (HPLC)IX on a Du Pont-850 analytical chromatograph, using a Zorbax NH2 column (4.6 mm x 25 cm) and acetonitrile-water mixture (70:30) as a mobile phase. Sugars were detected by using a refractive index detector.Thermostatted glass vessels (100 mL volume) equipped with a magnetic stirrer were used as batchstirred reactors. The glass columns (8 and 40 mL total volume) equipped with a thermostat jacket and a porous glass filter at the outlet were used as plug-flow column reactors. Cellulose hydrolysis in the column has been described in detail in ref. 15. The concentration of cellulose in the column was 250 g/L. All the experiments were performed at 50°C and pH 4.5 (0.1M acetate buffer).The models for the enzymatic hydrolysis of cellulose in batch and plug-flow column reactors have been described in detail...

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“…It is also possible that the xylanase was repressed in a similar fashion with the accumulated hydrolysis products resulting in catabolite repression of enzyme production at higher substrate concentration. The other reason for this may be due to irreversible adsorption of enzyme (Klyosov and Rabinowitch, 1980) which was accelerated particularly by the high bulk density of the medium.…”

Section: Effect Of Other Parametersmentioning

confidence: 99%

Production of xylanases by Bacillus polymyxa using lignocellulosic wastes

Pham

Taillandier

Delmas³

et al. 1998

Industrial Crops and Products

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Production of xylanolytic enzymes with no detectable cellulase activity was investigated using two strains of Bacillus polymyxa. The optimum pH and temperature for activities of the two xylanases ranged from 6.0 to 7.0 and from 45 to 50°C, respectively. The highest titres of xylanase, up to 24 nKat ml − 1 were produced within 36 and 42 h, respectively in shake flask cultures at 30°C. Enzyme production showed a cell growth associated profile. One of two strains, B. polymyxa CECT 153 was chosen for further detailed study. Numerous carbohydrates were examined for their ability to induce xylanase. It was found that xylan or xylan containing substrates, such as wheat straw, induced maximum and comparable levels of xylanase, while pure cellulose (avicel, h-cellulose) and the easily metabolisable sugars (glucose, sucrose) did not improve xylanase synthesis. Low levels of constitutive enzyme were produced as evidence from the culture medium without carbon source addition. Among various nitrogen sources tested, yeast extract was optimal for the production of xylanase.

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Enzymatic Conversion of Cellulose to Glucose: Present State of the Art and Potential

Cited by 24 publications

References 28 publications

Cellulases of Penicillium verruculosum

Cellulases of Penicillium verruculosum

Factors affecting the enzymatic hydrolysis of cellulose in batch and continuous reactors: Computer simulation and experiment

Production of xylanases by Bacillus polymyxa using lignocellulosic wastes

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