Cellulose degradation by Clostridium thermocellum: From manure to molecular biology

Béguin, Pierre; Millet, J; Aubert, Jean-Paul

doi:10.1111/j.1574-6968.1992.tb05750.x

Cited by 32 publications

(15 citation statements)

References 52 publications

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“…Although this discussion focuses primarily on the action of hydrolytic enzyme systems on cellulose, it should be realized that such systems are also active on hemicellulose, and enzymes active specifically on hemicellulose are commonly coproduced by cellulolytic microorganisms. Prior reviews consider the complexed cellulases of anaerobic bacteria (31,33,36,37,38,39,40,41,43,165,166,182,383,565,606,621), noncomplexed fungal and bacterial cellulases (122,349,579,653,672,673,756), cellulase structure and catalytic mechanisms (58,136,470,624,683,722,757,758), cellulase (hydrolase) families (254,255,256,258,260), and biotechnological applications (52,214,501,604,605).…”

Section: Cellulase Enzyme Systemsmentioning

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: Cellulase Enzyme Systemsmentioning

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

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“…A possible reason might be that it interacts preferentially with the duplicated segment of CipA rather than with those of the catalytic components. A diagram summarizing this hypothesis and extending previous models of the cellulosome (2,14,27) is presented in Fig. 6.…”

Section: Resultsmentioning

confidence: 99%

Organization of a Clostridium thermocellum gene cluster encoding the cellulosomal scaffolding protein CipA and a protein possibly involved in attachment of the cellulosome to the cell surface

1993

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The nucleotide sequence was determined for a 9.4-kb region of Clostridium thermocellum DNA extending from the 3' end of the gene (now termed cipA), encoding the S1/SL component of the cellulosome. Three open reading frames (ORFs) belonging to two operons were detected. They encoded polypeptides of 1,664, 688, and 447 residues, termed ORF1p, ORF2p, and ORF3p, respectively. The COOH-terminal regions of the three polypeptides were highly similar and contained three reiterated segments of 60 to 70 residues each. Similar segments have been found at the NH2 terminus of the S-layer proteins of Bacillus brevis and Acetogenium kivui, suggesting that ORF1p, ORF2p, and ORF3p might also be located on the cell surface. Otherwise, the sequence of ORF1p and ORF2p gave little clue concerning their potential function. However, the NH2-terminal region of ORF3p was similar to the reiterated domains previously identified in CipA as receptors involved in binding the duplicated segment of 22 amino acids present in catalytic subunits of the cellulosome. Indeed, it was found previously that ORF3p binds 125I-labeled endoglucanase CelD containing the duplicated segment (T. Fujino, P. Béguin, and J.-P. Aubert, FEMS Microbiol. Lett. 94:165-170, 1992). These findings suggest that ORF3p might serve as an anchoring factor for the cellulosome on the cell surface by binding the duplicated segment that is present at the COOH end of CipA.

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“…It contains approximately 1,850 amino acid residues and is the most important protein of the cellulosome. In addition to its function of binding other members of the cellulase complex to itself, it also binds to cellulose (33). Our first cloning and sequencing of cipA involved a truncated 5Ј region (277).…”

Section: Components S L and S Smentioning

confidence: 99%

Cellulase, Clostridia, and Ethanol

Demain

Newcomb

2005

Microbiol Mol Biol Rev

804

579

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SUMMARY Biomass conversion to ethanol as a liquid fuel by the thermophilic and anaerobic clostridia offers a potential partial solution to the problem of the world's dependence on petroleum for energy. Coculture of a cellulolytic strain and a saccharolytic strain of Clostridium on agricultural resources, as well as on urban and industrial cellulosic wastes, is a promising approach to an alternate energy source from an economic viewpoint. This review discusses the need for such a process, the cellulases of clostridia, their presence in extracellular complexes or organelles (the cellulosomes), the binding of the cellulosomes to cellulose and to the cell surface, cellulase genetics, regulation of their synthesis, cocultures, ethanol tolerance, and metabolic pathway engineering for maximizing ethanol yield.

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Cellulose degradation by Clostridium thermocellum: From manure to molecular biology

Cited by 32 publications

References 52 publications

Microbial Cellulose Utilization: Fundamentals and Biotechnology

Microbial Cellulose Utilization: Fundamentals and Biotechnology

Organization of a Clostridium thermocellum gene cluster encoding the cellulosomal scaffolding protein CipA and a protein possibly involved in attachment of the cellulosome to the cell surface

Cellulase, Clostridia, and Ethanol

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