Construction and comparison of recombinant Escherichia coli strains harboring the polyhydroxybutyrate (PHB) operon from Ralstonia eutropha using vectors possessing different promoters, as well as the production of PHB from soy waste by the recombinant strain, are reported. The lac promotor was the most efficient on expression of the phb operon among the three promoters studied: i.e., lac promotor, T7 promotor and the normal sigma(70) promotor. The pKS/PHB was the most efficient plasmid for phb operon expression among the three plasmids used: i.e., pKS(-), pAED4, and pJM9131. It was observed that isopropyl-beta-D-thiogalactopyranoside was not required for the induction of the expression of phb operon. The cell dry wt and polyhydroxyalkanoate content by E. coli XL-1 Blue (pKS/PHB) were 3.025 g/L and 27.83%, respectively.