Specialized transducing phages rho 11spoIIC and phi 105spoIIC, carrying the Bacillus subtilis sporulation gene spoIIC, were constructed by the prophage transformation method. An EcoRI fragment (2.4 MDal) carrying the spoIIC gene was isolated from the phi 105spoIIC genome and recloned into the EcoRI site of plasmid pUB110. The recombinant plasmids corrected the sporulation defect of a Spo- Rec- host, but slightly inhibited the sporulation of a Spo+ Rec- host.