Clostridium cellulolyticum: model organism of mesophilic cellulolytic clostridia
- 30 September 2005
- journal article
- review article
- Published by Oxford University Press (OUP) in FEMS Microbiology Reviews
- Vol. 29 (4), 741-764
- https://doi.org/10.1016/j.femsre.2004.11.003
Abstract
Clostridium cellulolyticum ATCC 35319 is a non-ruminal mesophilic cellulolytic bacterium originally isolated from decayed grass. As with most truly cellulolytic clostridia, C. cellulolyticum possesses an extracellular multi-enzymatic complex, the cellulosome. The catalytic components of the cellulosome release soluble cello-oligosaccharides from cellulose providing the primary carbon substrates to support bacterial growth. As most cellulolytic bacteria, C. cellulolyticum was initially characterised by limited carbon consumption and subsequent limited growth in comparison to other saccharolytic clostridia. The first metabolic studies performed in batch cultures suggested nutrient(s) limitation and/or by-product(s) inhibition as the reasons for this limited growth. In most recent investigations using chemostat cultures, metabolic flux analysis suggests a self-intoxication of bacterial metabolism resulting from an inefficiently regulated carbon flow. The investigation of C. cellulolyticum physiology with cellobiose, as a model of soluble cellodextrin, and with pure cellulose, as a carbon source more closely related to lignocellulosic compounds, strengthen the idea of a bacterium particularly well adapted, and even restricted, to a cellulolytic lifestyle. The metabolic flux analysis from continuous cultures revealed that (i) in comparison to cellobiose, the cellulose hydrolysis by the cellulosome introduces an extra regulation of entering carbon flow resulting in globally lower metabolic fluxes on cellulose than on cellobiose, (ii) the glucose 1-phosphate/glucose 6-phosphate branch point controls the carbon flow directed towards glycolysis and dissipates carbon excess towards the formation of cellodextrins, glycogen and exopolysaccharides, (iii) the pyruvate/acetyl-CoA metabolic node is essential to the regulation of electronic and energetic fluxes. This in-depth analysis of C. cellulolyticum metabolism has permitted the first attempt to engineer metabolically a cellulolytic microorganism.Keywords
This publication has 99 references indexed in Scilit:
- Solution structure of the module X2_1 of unknown function of the cellulosomal scaffolding protein CipC of Clostridium cellulolyticumJournal of Molecular Biology, 2000
- Crystal structure of a cohesin module from Clostridium cellulolyticum: implications for dockerin recognitionJournal of Molecular Biology, 2000
- La dégradation de la celluloseBiofutur, 2000
- Cellulose biosynthesis in higher plantsTrends in Plant Science, 1996
- Expression, purification and subunit‐binding properties of cohesins 2 and 3 of the Clostridium thermocellum cellulosomeFEBS Letters, 1995
- Growth inhibition and pyruvate overflow during glucose metabolism of Eubactevium limosum are related to a limited capacity to reassimilate CO2 by the acetyl-CoA pathwayJournal of General Microbiology, 1993
- Partial purification and characterization of the cellulases from clostridium cellulolyticum h10Journal of Chemical Technology & Biotechnology, 1991
- Sequence analysis of the Clostridium cellulolyticum endoglucanase-A-encoding gene, celCCAGene, 1989
- Bioconversion of organic carbon to CH4and CO2Geomicrobiology Journal, 1987
- Control of Lactate Production by Selenomonas ruminantium: Homotropic Activation of Lactate Dehydrogenase by PyruvateJournal of General Microbiology, 1978