The expression vector includes: the nucleic acids coding for the polypeptides forming a polypeptide complex having an enzyme activity allowing acetoacetyl-CoA to be converted to acetoacetate; optionally, at least one nucleic acid coding for a polypeptide having an enzyme activity allowing acetoacetate to be converted to acetone; and at least one nucleic acid coding for a polypeptide having an enzyme activity allowing acetone to be converted to isopropanol; the expression of the nucleic acids being controlled by a single constitutive promoter located upstream of the abovementioned nucleic acids.