Insights from genome of Clostridium butyricum INCQS635 reveal mechanisms to convert complex sugars for biofuel production.

Clostridium butyricum is widely used to produce organic solvents such as ethanol, butanol and acetone. We sequenced the entire genome of C. butyricum INCQS635 by using Ion Torrent technology. We found a high contribution of sequences assigned for carbohydrate subsystems (15-20 % of known sequences). Annotation based on protein-conserved domains revealed a higher diversity of glycoside hydrolases than previously found in C. acetobutylicum ATCC824 strain. More than 30 glycoside hydrolases (GH) families were found; families of GH involved in degradation of galactan, cellulose, starch and chitin were identified as most abundant (close to 50 % of all sequences assigned as GH) in C. butyricum INCQS635. KEGG metabolic pathways reconstruction allowed us to verify possible routes in the C. butyricum INCQS635 and C. acetobutylicum ATCC824 genomes. Metabolic pathways for ethanol synthesis are similar for both species, but alcohol dehydrogenase of C. butyricum INCQS635 and C. acetobutylicum ATCC824 was different. The genomic repertoire of C. butyricum is an important resource to underpin future studies towards improved solvents production.