Molecular cloning of an alcohol (butanol) dehydrogenase gene cluster from Clostridium acetobutylicum ATCC 824.

In Clostridium acetobutylicum, conversion of butyraldehyde to butanol is enzymatically achieved by butanol dehydrogenase (BDH). A C. acetobutylicum gene that encodes this protein was identified by using an oligonucleotide designed on the basis of the N-terminal amino acid sequence of purified C. acetobutylicum NADH-dependent BDH. Enzyme assays of cell extracts of Escherichia coli harboring the clostridial gene demonstrated 15-fold-higher NADH-dependent BDH activity than untransformed E. coli, as well as an additional NADPH-dependent BDH activity. Kinetic, sequence, and isoelectric focusing analyses suggest that the cloned clostridial DNA contains two or more distinct C. acetobutylicum enzymes with BDH activity.