FIG. 1.
Plasmids used for construction of lux mutants. The region of the chromosome containing the lux regulon is shown, with arrows demonstrating the direction of transcription of the two transcriptional units. Relevant restriction enzyme sites are indicated. Plasmid constructs that were used to make mutations in the chromosomal copy of the lux genes are also shown. Black boxes indicate the location of the mutation resulting from either a deletion and gene replacement with the erm gene or a frameshift mutation (see Materials and Methods); the box with diagonal stripes depicts the location of a lacIq/Ptac cassette.