We have shown that the control of solventogenesis and sporulation can be genetically uncoupled in C. acetobutylicum. In strain 824(pASspo), the absence of SpoIIE causes sporulation to be blocked at stage II. The cell remains in a vegetative state, and this allows solvent production to proceed for longer and for solvents to accumulate more rapidly and to a higher concentration. The characteristic drop in OD600 observed in wild type and control strains of C. acetobutylicum after 48-72 hours as the cells transition from the solventogenic phase to sporulation is notably absent in the fermentations of 824(pASspo). Mutant S (wild type background, spoIIE disrupted), Mutant BS (Mutant B background, spoIIE disrupted), Mutant HS (Mutant H background, spoIIE disrupted) and Mutant bukS (buk- background, spoIIE disrupted) were generated to create stable solvent producing bacteria with complete inactivation of the SpoIIE protein. Similarity between the SpoIIE protein of C. acetobutylicum, B. subtilis, and other Clostridial species indicates that the techniques used in C. acetobutylicum can be applied to other solvent producing Clostridia.