Abstract: This invention relates to the expression and accumulation in bacterial cells of heterologous polypeptides under the control of the recA promoter/operator region. One such polypeptide comprises a recA/somatostatin fusion polypeptide. This fusion polypeptide has been expressed and accumulated by E. coli with much greater effectiveness than other somatostatin-containing fusion polypeptides. In addition, use of the recA promoter/opeerator region provides greater induction flexibility than other inducible promoter systems.