TTGE sensitivity in mixed cultures as a function of relative DNA concentrations. V3 16S rDNA fragments were PCR amplified from mixtures of two DNA samples present at different proportions and subjected to TTGE analyses. In the mixtures, the relative proportions of DNAs extracted from the two species varied from 1:1 to 1:0.001. The positions of the bands for the three reference strains used in this study are indicated on the right (Z739, CNRZ739; IL7, IL7; Z1896, CNRZ1896). (A) Lanes M, identification ladder; lane 1, CNRZ739 plus IL7; lane 2, CNRZ739 plus IL7 (1:10); lane 3, CNRZ739 plus IL7 (1:100); lane 4, CNRZ739 plus IL7 (1:1,000); lane 5, CNRZ739 plus CNRZ1896; lane 6, CNRZ739 plus CNRZ1896 (1:10); lane 7, CNRZ739 plus CNRZ1896 (1:100); lane 8, CNRZ739 plus CNRZ1896 (1:1,000); lane 9, IL7 plus CNRZ739 (1:10); lane 10, IL7 plus CNRZ739 (1:100); lane 11, IL7 plus CNRZ739 (1:1,000). (B) Lanes M, identification ladder; lane 1, IL7 plus CNRZ1896; lane 2, IL7 plus CNRZ1896 (1:10); lane 3, IL7 plus CNRZ1896 (1:100); lane 4, IL7 plus CNRZ1896 (1:1,000); lane 5, CNRZ1896 plus CNRZ739 (1:10); lane 6, CNRZ1896 plus CNRZ739 (1:100); lane 7, CNRZ1896 plus CNRZ739(1:1,000); lane 8, CNRZ1896 plus IL7 (1:10); lane 9, CNRZ1896 plus IL7 (1:100); lane 10, CNRZ1896 plus IL7 (1:1,000); lane 11, negative control.