Characterization of the cellulolytic complex (cellulosome) of<i>Clostridium acetobutylicum</i>

Sabathé, Fabrice; Belaı̈ch, Anne; Soucaille, Philippe

doi:10.1111/j.1574-6968.2002.tb11450.x

Cited by 113 publications

(33 citation statements)

References 35 publications

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“…In theory, glycosyltransferases can be necessary for regulatory purposes, but the increased expression levels of enzymes for xylan and starch metabolism cannot be explained at this point because the synthetic medium used in the chemostat cultures contained a surplus of glucose as single carbon and energy source. Furthermore, referring to the increased expression of putative gene products involved in cellulose degradation ( cac0910 – cac0915 and cac0918 – cac0919 ), it must be mentioned that C. acetobutylicum cannot utilize cellulose (Lee et al 1985a) although the genome comprises several genes encoding parts of the cellulosome and its assembly (López-Contreras et al 2003, 2004; Sabathé et al 2002). On the other hand, xylanolytic activity of C. acetobutylicum is well known (Lee et al 1985b), and xylan and xylooligosaccharide hydrolyzing activities were demonstrated for the xylanases CAP0053 (formerly Xyn10A) and CAP0116 (formerly Xyn10B) (Mursheda et al 2004, 2005).…”

Section: Discussionmentioning

confidence: 99%

A proteomic and transcriptional view of acidogenic and solventogenic steady-state cells of Clostridium acetobutylicum in a chemostat culture

Janssen

Döring

Ehrenreich

et al. 2010

Appl Microbiol Biotechnol

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The complex changes in the life cycle of Clostridium acetobutylicum, a promising biofuel producer, are not well understood. During exponential growth, sugars are fermented to acetate and butyrate, and in the transition phase, the metabolism switches to the production of the solvents acetone and butanol accompanied by the initiation of endospore formation. Using phosphate-limited chemostat cultures at pH 5.7, C. acetobutylicum was kept at a steady state of acidogenic metabolism, whereas at pH 4.5, the cells showed stable solvent production without sporulation. Novel proteome reference maps of cytosolic proteins from both acidogenesis and solventogenesis with a high degree of reproducibility were generated. Yielding a 21% coverage, 15 protein spots were specifically assigned to the acidogenic phase, and 29 protein spots exhibited a significantly higher abundance in the solventogenic phase. Besides well-known metabolic proteins, unexpected proteins were also identified. Among these, the two proteins CAP0036 and CAP0037 of unknown function were found as major striking indicator proteins in acidogenic cells. Proteome data were confirmed by genome-wide DNA microarray analyses of the identical cultures. Thus, a first systematic study of acidogenic and solventogenic chemostat cultures is presented, and similarities as well as differences to previous studies of batch cultures are discussed.Electronic supplementary materialThe online version of this article (doi:10.1007/s00253-010-2741-x) contains supplementary material, which is available to authorized users.

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Section: Discussionmentioning

confidence: 99%

A proteomic and transcriptional view of acidogenic and solventogenic steady-state cells of Clostridium acetobutylicum in a chemostat culture

Janssen

Döring

Ehrenreich

et al. 2010

Appl Microbiol Biotechnol

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“…However, cellulosomes are multienzyme complexes having high activity against crystalline cellulose are being analyzed in Clostridia. 30 The lignocellulosic biomass is the most abundant renewable resource on the earth for biofuel production. 31,32 Countries like India alone generates over 370 million tonnes of biomass every year directly from plants, rice husk from rice mills, saw dust from saw mills, bagasse from sugar mills etc.…”

Section: Biomass For Biobutanolmentioning

confidence: 99%

Biobutanol: the outlook of an academic and industrialist

et al. 2013

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The gradual shift of transportation fuels from oil based fuels to the alternative fuel resources and worldwide demand for energy has been the impetus for research to produce alcohol biofuels from renewable resources. Current bioethanol and biodiesel can, however, not cover an increasing demand for biofuels. Hence, there is an extensive need for advanced biofuels with superior fuel properties. The present review is focused on the developments of biobutanol, which is regarded to be superior to bioethanol in terms of energy density and hygroscopicity. Although acetone-butanolethanol (ABE) fermentation is one of the oldest large-scale fermentation processes, butanol yield by anaerobic fermentation remains sub-optimal. For sustainable industrial scale butanol production, a number of obstacles need to be addressed including choice of feedstock, low product yield, product toxicity to production strain, multiple end-products and downstream processing of alcohol mixtures.Metabolic engineering provides a means for fermentation improvements. Different strategies are employed in the metabolic engineering of Clostridia that aim to enhance the solvent production, improve selectivity for butanol production, and increase the tolerance of Clostridia to solvents. The introduction and expression of a non-clostridial butanol producing pathway in E. coli is most promising strategy for butanol biosynthesis. Several rigorous kinetic and physiological models for fermentation have been formulated, which form useful tool for optimization of the process. Due to the lower butanol titers in the fermentation broth, simultaneous fermentation and product removal techniques have been developed to improve production economics. With the use of new strains, inexpensive substrates, and superior reactor designs, economic ABE fermentation may further attract an attention of researchers all over the world. The present review is attempting to provide an overall outlook on discoveries and strategies that are being developed for commercial n-butanol production.

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“…The expression of the cellulosomal proteins is influenced by substrate availability and extracellular polysaccharides (8). Most cellulase and hemicellulase genes of C. thermocellum are scattered throughout the genome in small clusters, in contrast to the larger operons in mesophilic cellulolytic clostridia (9)(10)(11)(12)(13)(14)(15)(16). Methods of sensing and coordinating gene expression must therefore exist to allow the organism to utilize cellodextrins in plant biomass (17).…”

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confidence: 99%

LacI Transcriptional Regulatory Networks in Clostridium thermocellum DSM1313

Wilson

Klingeman

Schlachter

et al. 2017

Appl Environ Microbiol

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Organisms regulate gene expression in response to the environment to coordinate metabolic reactions. Clostridium thermocellum expresses enzymes for both lignocellulose solubilization and its fermentation to produce ethanol. One LacI regulator termed GlyR3 in C. thermocellum ATCC 27405 was previously identified as a repressor of neighboring genes with repression relieved by laminaribiose (a ␤-1,3 disaccharide). To better understand the three C. thermocellum LacI regulons, deletion mutants were constructed using the genetically tractable DSM1313 strain. DSM1313 lacI genes Clo1313_2023, Clo1313_0089, and Clo1313_0396 encode homologs of GlyR1, GlyR2, and GlyR3 from strain ATCC 27405, respectively. Growth on cellobiose or pretreated switchgrass was unaffected by any of the gene deletions under controlled-pH fermentations. Global gene expression patterns from time course analyses identified glycoside hydrolase genes encoding hemicellulases, including cellulosomal enzymes, that were highly upregulated (5-to 100-fold) in the absence of each LacI regulator, suggesting that these were repressed under wild-type conditions and that relatively few genes were controlled by each regulator under the conditions tested. Clo1313_2022, encoding lichenase enzyme LicB, was derepressed in a ΔglyR1 strain. Higher expression of Clo1313_1398, which encodes the Man5A mannanase, was observed in a ΔglyR2 strain, and ␣-mannobiose was identified as a probable inducer for GlyR2-regulated genes. For the ΔglyR3 strain, upregulation of the two genes adjacent to glyR3 in the celC-glyR3-licA operon was consistent with earlier studies. Electrophoretic mobility shift assays have confirmed LacI transcription factor binding to specific regions of gene promoters. IMPORTANCE Understanding C. thermocellum gene regulation is of importance for improved fundamental knowledge of this industrially relevant bacterium. Most LacI transcription factors regulate local genomic regions; however, a small number of those genes encode global regulatory proteins with extensive regulons. This study indicates that there are small specific C. thermocellum LacI regulons. The identification of LacI repressor activity for hemicellulase gene expression is a key result of this work and will add to the small body of existing literature on the area of gene regulation in C. thermocellum.

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Characterization of the cellulolytic complex (cellulosome) ofClostridium acetobutylicum

Cited by 113 publications

References 35 publications

A proteomic and transcriptional view of acidogenic and solventogenic steady-state cells of Clostridium acetobutylicum in a chemostat culture

A proteomic and transcriptional view of acidogenic and solventogenic steady-state cells of Clostridium acetobutylicum in a chemostat culture

Biobutanol: the outlook of an academic and industrialist

LacI Transcriptional Regulatory Networks in Clostridium thermocellum DSM1313

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