Fig. 1

Southern blotting analysis of the double mutants. a Southern blotting design of mshA deletion. The gene mshA (1335 bp) was replaced by a hygromycin cassette (1608 bp) in the mutant. The restriction enzyme ClaI cuts within mshA but not within the hygromycin gene. It also cuts outside the cloned upstream (US) and downstream (DS) regions. Therefore, ClaI digestion of the wild-type genomic DNA and the mutant genomic DNA, yield distinct fragment sizes at the deleted region. These fragments are detected using a digoxigenin labelled DNA fragment (probe) that is able to hybridize to both fragments b Southern blotting results of the wild-type and mutants. Since the gene mshA is still intact in the wild-type strain, the 6361 bp fragment is detected. However, since mshA is replaced by the hygromycin cassette in the mutant, a bigger fragment is detected (15,526 bp)