Effect of chemical modification of cellulose on the activity of a cellulase from <i>Aspergillus niger</i>

Boyer, Rodney F.; Redmond, Molly A.

doi:10.1002/bit.260250511

Cited by 11 publications

(2 citation statements)

References 24 publications

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“…Thus, any structural feature of cellulose or its constituents that limits its accessibility will exert an influence on the susceptibility or the reactivity of the cellulose. The degradability of a substrate is strongly affected by degree of polymerization, degree of substitution, crystallinity, available surface area, pore volume and its distribution, and association with hemicellulose and lignin (Boyer and Redmond, 1983;Gharpuray et al, 1983;Henrissat, et al, 1985;Lin et al, 1985;Puri, 1984;Ryu et al, 1982).…”

Section: Cellulasementioning

confidence: 99%

Cellulase activity of soils and the effect of tillage management on enzyme activities in soils

Deng

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APPENDIX 215 carbon side chain. It is formed by polycondensation (chemical reaction) of phenolic compounds and free radicals. Thus, it does not show a specific order. In addition, it is very inert (Paul and Clark, 1989). Hemicelluloses are various polymers of hexoses, pentoses, and sometimes, uronic acids. In the pure state, hemicelluloses are easily decomposed. In nature, however, they are frequently complexed with other substances that may make the breakdown more difficult. Enzymatic degradability of cellulose is closely related to its structure, forms, and its association with lignin and hemiceUulose. As Eriksson (1981) and Schwald et al. (1988) indicated, the resistance of native cellulose to enzymatic hydrolysis is due, in part, to its intrinsic properties and to the fact that its association with lignin, the polysaccharides, hemiceUulose and pectin, hinder access by cellulolytic enzymes. In addition, hydrogen bonding holds the cellulose molecules together. As a result, these fibers are composed of crystalline or highly ordered regions and less ordered, amorphous regions. This results in differences in reactivity and adsorption of the substrate by the cellulolytic enzyme due to its accessibility, degree of polymerization, or variation in crystal structure. Biodégradation of Cellulose Cellulose in soils is derived mainly from photosynthesis of higher plants.

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Section: Cellulasementioning

confidence: 99%

Cellulase activity of soils and the effect of tillage management on enzyme activities in soils

Deng

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“…The soluble nature of NaCMC is responsible for its rapid rate of enzymic hydrolysis; the free acid form of CMC is even more slowly hydrolyzed by fungal (Aspergillus niger) cellulase complex than is native cellulose, perhaps as a result of charge repulsion between the carboxyl groups of cellulose and the anionic cellulase enzymes. 194 In fact, it might be argued from a chemical engineering standpoint that NaCMC, while generally regarded as an analog of cellulose, is actually more similar to ceilodextrins in that both are soluble and noncrystalline, and their enzymatic hydrolysis can be modeled by conventional homogeneous catalysis.…”

Section: Biochemistrymentioning

confidence: 99%

Cellulose Degradation by Ruminal Microorganisms

Weimer

1992

Critical Reviews in Biotechnology

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The rumen i s a highly developed digestive organ in which feed material, particularly plant fiber, is efficiently digested by a complex microbial fermentation. Cellulose, the major component of plant fiber, is digested in the rumen by an assemblage of anaerobic bacteria, fungi, and protozoa. While pure cellulose itself is completely digestible under the proper environmental conditions, the matrix interactions among structural biopolymers in natural plant material prevent the complete digestion of the cellulose component. Ruminal bacterial are probably the most active cellulose degraders in the rumen, but the fungi also play an important role, particularly in the physical disruption of recalcitrant tissue to render the cellulose more accessible to degradative enzymes. Cellulose degradation in the rumen is enhanced by attachment of microbial cells to the substrate and by synergistic interactions with noncellulolytic microbes, but is inhibited by factors that produce a low ruminal pH. Recent advances in continuous culture techniques and in the molecular biology of cellulase enzymes have permitted a better understanding of the cellulolytic process. Enhancement of ruminal cellulose fermentation will be best achieved in the near term by exploitation of recent improvements in the technology of substrate pretreatment. However, advances in the development of improved rumen microbial strains and more digestible forage varieties may yield additional improvements in ruminant cellulose utilization.

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Relationship between the fine structure of native cellulose and cellulose degradability by the cellulase complexes of Trichoderma reesei and Clostridium thermocellum

Weimer

Weston

1985

Biotech & Bioengineering

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The initial rate of hydrolysis of six commercially available native (type l) celluloses was determined for the crude cellulase complexes of the thermophilic anaerobic bacterium C. thermocellum and the mesophilic fungus T. reesei. These rates were then compared with certain physical features of the substrates in an attempt to determine the role of cellulose structure in its degradability. Within the substrate series tested, the Clostridium system showed a greater relative range in rate of enzymatic hydrolysis than did the Trichoderma system. Average correlation coefficients for the kinetic rates from bacterial and fungal cellulases, respectively, and the following physical parameters were obtained: relative crystallinity index (RCl) from acid hydrolysis, -0.61 and -0.85; RCl from x-ray diffraction, -0.75 and -0.89; accessibility to formylation at 4 degrees C, + 0.49 and +0.60; nonaccessibility to formylation at 65 degrees C, -0.40 and -0.73; fiber saturation point, + 0.83 and + 0.85. Kinetic and pore volume distribution data suggest that the rate-limiting components of both the bacterial and fungal cellulase systems are of similar size, approximately 43 A along one axis.

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Effect of chemical modification of cellulose on the activity of a cellulase from Aspergillus niger

Cited by 11 publications

References 24 publications

Cellulase activity of soils and the effect of tillage management on enzyme activities in soils

Cellulase activity of soils and the effect of tillage management on enzyme activities in soils

Cellulose Degradation by Ruminal Microorganisms

Relationship between the fine structure of native cellulose and cellulose degradability by the cellulase complexes of Trichoderma reesei and Clostridium thermocellum

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