Project description:The transcriptome analysis by microarray was applied on wild-type and degenerated strains of C. beijerinckii NCIMB8052 (WT-8052 and DG-8052, respectively) to elucidate its mechanism of degeneration during solvent fermentation. The comparison of gene expression pattern in relation to ABE production is expected to provide insights toward metabolically engineering of C. beijerinckii NCIMB8052 with prevention of degeneration and eventually enhancement of ABE production.
Project description:Clostridium acetobutylicum is a typical bacterium of major importance to industrial butanol production. In order to dissect the regulatory network pertaining to the industrial application of this bacterium, catabolite control protein A (CcpA) was investigated for its global function by DNA microarray.It showed that CcpA of C. acetobutylicum controls hundreds of genes, not only carbon metabolism, but also solvent production and sporulation in the life cycle.The results here demonstrated that CcpA is an important pleiotropic regulator related to some specific physiological and biochemical process in butanol-producing C. acetobutylicum.
Project description:The impacts of ferulic acid, a phenolic compound commonly found in lignin hydrolysates, on the growth, solvent production and transcriptional responses of C. beijerinckii NCIMB 8052 were determined. Addition of ferulic acid to growing cultures resulted in a decrease in the growth and solvent production by 30 and 25%, respectively, when compared to the control cultures. To better understand the toxicity of this compound, microarray analyses were performed using samples taken from these cultures at three different growth states. Several gene ontology terms and KEGG pathways were identified showing significant change at each status, including ABC transporters, two component system and oxidoreductase activity. Moreover, genes related with efflux systems and heat shock proteins were also strongly up- regulated. Among these, expression of the groESL operon was induced by more than 4-fold and was consequently selected for overexpression to improve C. beijerinckii tolerance to ferulic acid.
Project description:In this study the transcriptional behavior of the natural solvent producing bacterium Clostridium acetobutylicum was investigated following n-butanol stress using DNA microarray analysis. Therefore, a phosphate-limited chemostat culture was established and n-butanol stress (0.9%) was added to acidogenic cells at pH 5.7.
Project description:In this study the transcriptional behavior of the natural solvent producing bacterium Clostridium acetobutylicum was investigated following n butanol stress using DNA microarray analysis. Therefore, a phosphate-limited chemostat culture was established and n-butanol stress (0.9%) was added to acidogenic cells at pH 5.7.
Project description:Solventogenic Clostridium species ferment carbohydrates to acetone, butanol and ethanol which are well-known next-generation biofuels. However, repeated subculture of or continuous fermentation by Clostridium often decreases and eventually terminates the solvent production and spore formation, which is a process called strain degeneration. Supplementation of CaCO3 to fermentation medium could partially recover metabolism of degenerated strain by more than 50% increase of cell growth and solvent production. The transcriptome profile of Clostridium beijerinckii NCIMB 8052 (DG-8052) and its response to CaCO3 treatment were analysed by microarray. Since fermentation by C. beijerinckii NCIMB 8052 is a biphasic process, gene expressions of two fermentations were compared at each stage, i.e. 12h and 24h fermentation time representing acidogenic phase and solventogenic phase, respectively. This study examined expression of 5168 genes capturing 98.6% of the C. beijerinckii NCIMB 8052 genome. With the addition of CaCO3, DG-8052 had 565 and 916 genes significantly up-regulated at acidogenic phase and solventogenic phase, respectively. According to the enrichment analysis of pathway and Gene Ontology terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, these genes were significantly overrepresented in cellular functions such as Amino acid transport and metabolism, organic acid biosynthetic process, bacteria chemotaxis and defense mechanisms. On the other hand, there were 704 and 1044 genes significantly down-regulated at acidogenic phase and solventogenic phase, respectively. These repressed genes were mainly enriched in functions such as ion transmembrane transport, ATP synthesis, oxidative phosphorylation.
