Effect of cocultures on the production of butanol by Clostridium sp. [C. butyricum, C. pasteurianum, C. butylicum, and C. acetobutylicum]

One of the problems with the production of butanol by fermentation is that a mixture of other solvents, primarily acetone and ethanol, are also produced. The ratio of butanol to acetone to ethanol is approximately 6:3:1. If the metabolism of the Clostridium can be shifted away from acetone and ethanol, then a higher percentage of the sugar carbon can be converted to butanol. This study examines the effects that cocultures of Clostridium have on the yield of butanol from glucose. C. butyricum and C. pasteurianum produced high concentrations of butyric acid from these sugars. C. butylicum and C. acetobutylicum are capable of utilizing this butyric acid for energy, resulting in butanol production. By using combinations of these strains in coculture a higher initial conversion to butyric acid would be expected followed by a higher overall yield of butanol. This coculture would not be expected to have an increased tolerance for butanol in the fermentation broth. 6 references, 1 figure, 3 tables.