FIG. 2.

Detection of the kanamycin resistance gene inserted into mutant strain 26404lgt2 chromosomal DNA by Southern blotting. Lane 1, 10 ng of pUC4K (positive control, plasmid with a kanamycin resistance cassette) digested with EcoRI; lane 2, 800 ng of chromosomal DNA from mutant strain 26404lgt2 digested with EcoRV; lane 3, 800 ng of chromosomal DNA from strain 26404 digested with EcoRV; lane 4, 1 μl of digoxigenin-labeled DNA molecular weight marker III (Roche) (the sizes are shown in base pairs). Each digested sample was resolved on a 0.7% agarose gel, and Southern blotting was performed using a digoxigenin-labeled kanamycin resistance gene probe.