The degradation pattern of cellulose by extracellular cellulases of aerobic and anaerobic microorganisms

Puls, J.; Wood, Thomas M.

doi:10.1016/0960-8524(91)90096-3

Cited by 50 publications

(39 citation statements)

References 12 publications

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“…If this difference were due to crystallinity, then cellulose crystallinity should increase over the course of reaction. However, relatively constant crystallinity over the course of enzymatic hydrolysis has been observed in studies involving a variety of cellulase systems (149,178,201,374,381,547), although such crystallinity measurements may be due to artifacts (730).…”

Section: Rates Of Enzymatic Hydrolysismentioning

confidence: 99%

Microbial Cellulose Utilization: Fundamentals and Biotechnology

Lynd

Weimer

Zyl³

et al. 2002

Microbiol Mol Biol Rev

4,005

2,868

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Fundamental features of microbial cellulose utilization are examined at successively higher levels of aggregation encompassing the structure and composition of cellulosic biomass, taxonomic diversity, cellulase enzyme systems, molecular biology of cellulase enzymes, physiology of cellulolytic microorganisms, ecological aspects of cellulase-degrading communities, and rate-limiting factors in nature. The methodological basis for studying microbial cellulose utilization is considered relative to quantification of cells and enzymes in the presence of solid substrates as well as apparatus and analysis for cellulose-grown continuous cultures. Quantitative description of cellulose hydrolysis is addressed with respect to adsorption of cellulase enzymes, rates of enzymatic hydrolysis, bioenergetics of microbial cellulose utilization, kinetics of microbial cellulose utilization, and contrasting features compared to soluble substrate kinetics. A biological perspective on processing cellulosic biomass is presented, including features of pretreated substrates and alternative process configurations. Organism development is considered for “consolidated bioprocessing” (CBP), in which the production of cellulolytic enzymes, hydrolysis of biomass, and fermentation of resulting sugars to desired products occur in one step. Two organism development strategies for CBP are examined: (i) improve product yield and tolerance in microorganisms able to utilize cellulose, or (ii) express a heterologous system for cellulose hydrolysis and utilization in microorganisms that exhibit high product yield and tolerance. A concluding discussion identifies unresolved issues pertaining to microbial cellulose utilization, suggests approaches by which such issues might be resolved, and contrasts a microbially oriented cellulose hydrolysis paradigm to the more conventional enzymatically oriented paradigm in both fundamental and applied contexts

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Section: Rates Of Enzymatic Hydrolysismentioning

confidence: 99%

Microbial Cellulose Utilization: Fundamentals and Biotechnology

Lynd

Weimer

Zyl³

et al. 2002

Microbiol Mol Biol Rev

4,005

2,868

View full text Add to dashboard Cite

show abstract

“…If this hypothesis were correct, it would be expected that crystallinity should increase over the course of cellulose hydrolysis as a result of preferential reaction of amorphous cellulose (Betrabet and Paralikar, 1977;Ooshima et al, 1983). However, several studies have found that crystallinity does not increase during enzymatic hydrolysis (Lenze et al, 1990;Ohmine et al, 1983;Puls and Wood, 1991;Schurz et al, 1985;Sinitsyn et al, 1989). Considering both the uncertainty of methodologies for measuring CrI as well as conflicting results on the change of CrI during hydrolysis, it is difficult to conclude at this time that CrI is a key determinant of the rate of enzymatic hydrolysis (Lynd et al, 2002;Mansfield et al, 1999).…”

Section: Crystallinity Index (Cri)mentioning

confidence: 99%

Toward an aggregated understanding of enzymatic hydrolysis of cellulose: Noncomplexed cellulase systems

Zhang

Lynd

2004

Biotech & Bioengineering

1,640

1,284

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Information pertaining to enzymatic hydrolysis of cellulose by noncomplexed cellulase enzyme systems is reviewed with a particular emphasis on development of aggregated understanding incorporating substrate features in addition to concentration and multiple cellulase components. Topics considered include properties of cellulose, adsorption, cellulose hydrolysis, and quantitative models. A classification scheme is proposed for quantitative models for enzymatic hydrolysis of cellulose based on the number of solubilizing activities and substrate state variables included. We suggest that it is timely to revisit and reinvigorate functional modeling of cellulose hydrolysis, and that this would be highly beneficial if not necessary in order to bring to bear the large volume of information available on cellulase components on the primary applications that motivate interest in the subject. B

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“…This bacterium produces an extracellular multi-enzyme complex containing different types of glycosyl hydrolases, such as cellulases, hemicellulases, and carbohydrate esterases (cellulosome) on the surface of cell membranes Kumagai et al, 2014). The high capability of C. thermocellum in hydrolysis of different cellulosic materials, such as crystalline cellulose (Hörmeyer et al, 1988;Puls and Wood, 1991;Hall et al, 2010;Shao et al, 2011;Zhao et al, 2012), poplar (Populous tremuloides), wheat straw (Triticum vulgare) (Hörmeyer et al, 1988), and switch grass Yee et al, 2012) has been confirmed. Kundu et al (1983) could develop a direct anaerobic bioconversion of cellulosic substances (raw and mild alkali/steam pre-treated bagasse) into ethanol by C. thermocellum ATCC 27405.…”

Section: Clostridium Thermocellummentioning

confidence: 97%

Advances in consolidated bioprocessing systems for bioethanol and butanol production from biomass: a comprehensive review

2015

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HIGHLIGHTS Various CBP strategies have been discussed. Recently, lignocellulosic biomass as the most abundant renewable resource has been widely considered for bioalcohols production. However, the complex structure of lignocelluloses requires a multi-step process which is costly and time consuming. Although, several bioprocessing approaches have been developed for pretreatment, saccharification and fermentation, bioalcohols production from lignocelluloses is still limited because of the economic infeasibility of these technologies. This cost constraint could be overcome by designing and constructing robust cellulolytic and bioalcohols producing microbes and by using them in a consolidated bioprocessing (CBP) system. This paper comprehensively reviews potentials, recent advances and challenges faced in CBP systems for efficient bioalcohols (ethanol and butanol) production from lignocellulosic and starchy biomass. The CBP strategies include using native single strains with cellulytic and alcohol production activities, microbial co-cultures containing both cellulytic and ethanologenic microorganisms, and genetic engineering of cellulytic microorganisms to be alcohol-producing or alcohol producing microorganisms to be cellulytic. Moreover, high-throughput techniques, such as metagenomics, metatranscriptomics, next generation sequencing and synthetic biology developed to explore novel microorganisms and powerful enzymes with high activity, thermostability and pH stability are also discussed. Currently, the CBP technology is in its infant stage, and ideal microorganisms and/or conditions at industrial scale are yet to be introduced. So, it is essential to bring into attention all barriers faced and take advantage of all the experiences gained to achieve a high-yield and low-cost CBP process.

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The degradation pattern of cellulose by extracellular cellulases of aerobic and anaerobic microorganisms

Cited by 50 publications

References 12 publications

Microbial Cellulose Utilization: Fundamentals and Biotechnology

Microbial Cellulose Utilization: Fundamentals and Biotechnology

Toward an aggregated understanding of enzymatic hydrolysis of cellulose: Noncomplexed cellulase systems

Advances in consolidated bioprocessing systems for bioethanol and butanol production from biomass: a comprehensive review

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