sentence: To construct a lacZ driven by the spoIIQ promoter ( P ) containing a lacO operator for artificial repression by LacI , a DNA fragment containing the P was PCR amplified with primer pair oTK20 / oTK21 from chromosomal DNA of B. subtilis and cloned as an HindIII / BamHI fragment in pMUTIN4 , which was amplified with primer pair oTK22 / oTK23 , using plasmid pMUTIN4 ( ( Vagner et al ., 1998 ) as a template .