sentence: For stable expression , a single copy of the gene encoding the chimera was integrated into the genome and placed under control of a lacUV5 promoter , which is constitutively expressed in Salmonella.Despite the single copy background , substantial amounts of HbpD ( Δ d1 ) - ESAT6 were detected in the cell fraction of Salmonella using SDS-PAGE and Coomassie staining ( Figure 6A , lane 3 ) .