FIG. 4.

Presence of the gene pcbAB in penicillin-producing strains. EcoRI-digested genomic DNA from all the strains was electrophoresed (lanes 1 to 34); transferred to a nylon membrane; and hybridized with probes C, D, and E, which correspond to different portions of the pcbAB gene (Fig. 5). Strain numbers are as indicated in the legend to Fig. 3. Note that in P. verrucosum (lanes 21 and 22) there is a signal of 2.5 kb with probe C, which reveals the presence of the 3′ end of the pcbAB gene in this species. With probes D and E, a signal of about 12.5 kb can be observed that corresponds also to the pcbAB gene (see text).