BACKGROUND Butanol (n-butanol) has high values as a promising fuel source and chemical feedstock. Biobutanol is usually produced by the solventogenic clostridia through a typical biphasic (acidogenesis and solventogenesis phases) acetone-butanol-ethanol (ABE) fermentation process. It is well known that the acids produced in the acidogenic phase are significant and play important roles in the sw...

The fermentation carried out by the biofuel producer Clostridium acetobutylicum is characterized by two distinct phases. Acidogenesis occurs during exponential growth and involves the rapid production of acids (acetate and butyrate). Solventogenesis initiates as cell growth slows down and involves the production of solvents (butanol, acetone, and ethanol). Using metabolomics, isotope tracers, a...

Central to all clostridia is the orchestration of endospore formation (i.e., sporulation) and, specifically, the roles of differentiation-associated sigma factors. Moreover, there is considerable applied interest in understanding the roles of these sigma factors in other stationary-phase phenomena, such as solvent production (i.e., solventogenesis). Here we separately inactivated by gene disrup...

Clostridium beijerinckii DG-8052, derived from NCIMB 8052, cannot produce solvent or form spores, a phenomenon known as degeneration. To explore the mechanisms of degeneration at the gene level, transcriptomic profiles of the wild-type 8052 and DG-8052 strains were compared. Expression of 5168 genes comprising 98.6% of the genome was assessed. Interestingly, 548 and 702 genes were significantly...

DNA microarray analysis of Clostridium acetobutylicum was used to examine the genomic-scale gene expression changes during the shift from exponential-phase growth and acidogenesis to stationary phase and solventogenesis. Self-organizing maps were used to identify novel expression patterns of functional gene classes, including aromatic and branched-chain amino acid synthesis, ribosomal proteins,...

The bacterium Clostridium acetobutylicum produces acids as an energy-yielding process during exponential growth. An acidic environment, however, is toxic to the cells and two survival mechanisms are in place to prevent them from dying. Firstly, during a solventogenesis phase, the cells take up these acids and convert them to solvents, thus raising the environmental pH. Secondly, the cells under...

Clostridium beijerinckii is an anaerobic bacterium used for the fermentative production of acetone and butanol. The recent availability of genomic sequence information for C. beijerinckii NCIMB 8052 has allowed for an examination of gene expression during the shift from acidogenesis to solventogenesis over the time course of a batch fermentation using a ca. 500-gene set DNA microarray. The micr...

Clostridium acetobutylicum is able to switch from acidogenic growth to solventogenic growth. We used phosphate-limited continuous cultures that established acidogenic growth at pH 5.8 and solventogenic growth at pH 4.5. These cultures allowed a detailed transcriptomic study of the switch from acidogenesis to solventogenesis that is not superimposed by sporulation and other growth phase-dependen...

Using gene expression reporter vectors, we examined the activity of the spoIIE promoter in wild-type and spo0A-deleted strains of Clostridium acetobutylicum ATCC 824. In wild-type cells, the spoIIE promoter is active in a transient manner during late solventogenesis, but in strain SKO1, where the sporulation initiator spo0A is disrupted, no spoIIE promoter activity is detectable at any stage of...

The bacterium Clostridium acetobutylicum produces acids as an energy-yielding process during exponential growth. An acidic environment, however, is toxic to the cells and two survival mechanisms are in place to prevent them from dying. Firstly, during a solventogenesis phase, the cells take up these acids and convert them to solvents, thus raising the environmental pH. Secondly, the cells under...