FIG. 1.

Probe specificity during hybridization. L. lactis subsp. lactis IL1403 is analyzed after 30 min of growth in M17G at pH 7.0 (i.e., control condition as described in Materials and Methods). (A) Hybridization image demonstrated no cross-hybridization between genes with homologous sequences in the IL1403 genome. The arcA, arcB, arcC1, arcC2, arcD1, and arcD2 genes encoded proteins involved in the arginine deiminase pathway and belonged to arc gene clusters containing multiple promoter regions (4). (B) Box plot demonstrates low nonspecific hybridization in negative control probes (i.e., an empty spot, a random 15-mer, a probe designed from reverse complementary strand of dnaK, and probes from the plasmid-borne genes prtP and prtM). Box plot group 1 consisted of the signal medians in negative spots (before background correction), while group 2 consisted of the background medians in negative spots.